I try to eat a Mediterranean diet, characterized by high intakes of fish, vegetables, legumes, fruits, cereals and unsaturated fatty acids, low intakes of dairy products, meat and saturated fats and moderate alcohol consumption. Here’s why- with some notes on the kinds of food and cooking I try to avoid first:
“Western” diet increases heart attack risk globally
The typical Western diet — fried foods, salty snacks and meat — accounts for about 30 percent of heart attack risk across the world, according to a study of dietary patterns in 52 countries reported in Circulation: Journal of the American Heart Association.
Researchers identified three dietary patterns in the world:
• Oriental: higher intake of tofu, soy and other sauces;
• Prudent: higher intake of fruits and vegetables; and
• Western: higher intake of fried foods, salty snacks, eggs and meat.
The Prudent diet was associated with a lower heart attack risk than the Oriental, researchers said.
“The objective of this study was to understand the modifiable risk factors of heart attacks at a global level,” said Salim Yusuf, D.Phil., the study’s senior author.
Previous studies have reached similar conclusions about the Prudent and Western diet in the United States and Europe. This study broadens those findings and identifies a unique dietary pattern that researchers labeled “Oriental” (because of a higher content of food items typical of an Oriental diet.) The dietary pattern recommended by the American Heart Association is similar to the Prudent diet described in this study.
“This study indicates that the same relationships that are observed in Western countries exist in different regions of the world,” said Yusuf, professor of medicine at McMaster University and director of the Population Health Research Institute at Hamilton Health Sciences in Ontario, Canada.
Researchers analyzed the INTERHEART study, which documents the association of various risk factors and the risk of heart attack in about 16,000 participants in 52 countries. Here, they analyzed 5,761 heart attack cases and compared them to 10,646 people without known heart disease (controls).
The researchers created a dietary risk score questionnaire for heart attacks patients, based on 19 food groups and adjusted it for dietary preferences for each country. Trained medical personnel interviewed the heart attack patients and the control group. The questionnaires included healthy food items (such as fruits and vegetables) and unhealthy food items (such as fried foods and salty snacks).
“A simple dietary score, which included both good and bad foods with the higher score indicating a worse diet, showed that 30 percent of the risk of heart disease in a population could be related to poor diet,” said Romania Iqbal, Ph.D., lead author of the study.
After adjusting for known risk factors, researchers found:
• People who consumed the Prudent diet of more fruits and vegetables had a 30 percent lower risk of heart attack compared to people who ate little or no fruits and vegetables.
• People who consumed the Western diet had a 35 percent greater risk of having a heart attack compared to people who consumed little or no fried foods and meat.
• The Oriental pattern showed no relationship with heart attack risk.
Researchers said that while some components of the Oriental pattern may be protective, others such as the higher sodium content of soy sauces, may increase cardiovascular risk, neutralizing any relationship.
It’s expensive and time-consuming to establish a large and long-term study examining the relationship of diet and heart attack in every region of the world. So the approach of this study is the only feasible way to examine the relationship to diet and heart disease from multiple populations in a relatively short time at an affordable cost, Yusuf said.
Data from this study helped confirm that changes in dietary intake, including the consumption of more fruits and vegetables, can help reduce the risk of having a heart attack in populations worldwide, he said.
“At the same time, an unhealthy dietary intake, assessed by a simple dietary risk score, accounts for nearly one-third of the world population’s attributable risk,” Yusuf said.
French Fries and Potato Chips Are Dangerous
A new study published in the March 2009 American Journal of Clinical Nutrition by Marek Naruszewicz and colleagues from Poland suggests that acrylamide from foods may increase the risk of heart disease. Acrylamide has been linked previously to nervous system disorders and possibly to cancer. After ingesting large amounts of potato chips providing about 157 micrograms of acrylamide daily for four weeks, the participants had adverse changes in oxidized LDL, inflammatory markers and antioxidants that help the body eliminate acrylamide—all of which may increase the risk of heart disease. Additional research is needed in long-term studies of people consuming typical amounts of acrylamide (averaging about 20 to 30 micrograms).
It is recommended that FDA and the food industry continue to decrease acrylamide in foods by improving food processing technologies. FDA reports that acrylamide is particularly high in potato chips and French fries (http://www.cfsan.fda.gov/~dms/acrydata.html). According to American Society for Nutrition Spokesperson Mary Ann Johnson, PhD: "Consumers can reduce their exposure to acrylamide by limiting their intake of potato chips and French fries, choosing a variety of fruits, vegetables, whole grains, and low fat meat and dairy products, and quitting smoking, which is a major source of acrylamide."
Eating red meat sets up target for disease-causing bacteria
Non-human molecules absorbed by eating red meat increase risk of food poisoning in humans
Offering another reason why eating red meat could be bad for you, an international research team, including University of California, San Diego School of Medicine professor Ajit Varki, M.D., has uncovered the first example of a bacterium that causes food poisoning in humans when it targets a non-human molecule absorbed into the body through red meats such as lamb, pork and beef.
In findings to be published on line October 29th in advance of print in the journal Nature, the scientists discovered that a potent bacterial toxin called subtilase cytotoxin specifically targets human cells that have a non-human, cellular molecule on their surface. The molecule –N-glycolylneuraminic acid (Neu5Gc) – is a type of glycan, or sugar molecule, that humans don't naturally produce.
Subtilase cytotoxin is produced by certain kinds of E. coli bacteria, causing bloody diarrhea and a potentially fatal disease called haemolytic uraemic syndrome (HUS) in humans. Humans usually become infected after eating contaminated red meat, which is why this is also known as "hamburger" disease.
Varki, UC San Diego School of Medicine distinguished professor of medicine and cellular and molecular medicine, and co-director of the UCSD Glycobiology Research and Training Center, previously discovered that humans don't produce Neu5Gc because they lack the gene responsible for its production. Therefore, it was thought that humans should be resistant to the toxin.
"Ironically, humans may set themselves up for an increased risk of illness from this kind of E. coli bacteria present in contaminated red meat or dairy, because these very same products have high-levels of Neu5Gc," Varki explained. "The Neu5Gc molecule is absorbed into the body, making it a target for the toxin produced by E. coli."
In the Nature study, the researchers discovered that sites where the Neu5Gc has been incorporated into the human body coincide with toxin binding. "When the toxin binds to the non-human Neu5Gc receptors, it can result in serious food-poisoning and other symptoms in humans," said Varki. The research emphasizes the need for people to eat only well-cook meat or pasteurized dairy products, processes that destroy contaminating bacteria.
Five years ago, Varki and his colleagues at the UC San Diego School of Medicine published a paper in the Proceedings of the National Academy of Sciences describing how Neu5Gc is absorbed into human tissues – including the surface of cells lining the intestines and blood vessels – as a result of eating red meat and milk products. At the time, the researchers also showed that this foreign molecule generates an immune response that could potentially lead to inflammation in human tissues. The UC San Diego study was the first to investigate human dietary absorption of the Neu5Gc glycans which, while not produced in humans, does occur naturally in red meats. Levels are very low or undetectable in fruits, vegetables, eggs, poultry and fish. The researchers proved that people who ingest Neu5Gc incorporate some of it into their tissues, and demonstrated that many generated an immune response against the molecule, conjecturing that a lifetime of gradual incorporation of this glycan "invader" could result in disease.
Fried, Broiled, Grilled Foods = Bad Health
Study shows food preparation may play a bigger role in chronic disease than was previously thought_
How your food is cooked may be as important to your health as the food itself. Researchers now know more about a new class of toxins that might soon become as important a risk factor for heart disease and metabolic disorders as trans fats.
This class of toxins, called advanced glycation end products (AGEs), are absorbed into the body through the consumption of grilled, fried, or broiled animal products, such as meats and cheeses. AGEs, which are also produced when food products are sterilized and pasteurized, have been linked to inflammation, insulin resistance, diabetes, vascular and kidney disease, and Alzheimer’s disease.
A new study at Mount Sinai School of Medicine reveals that AGE levels are elevated in the blood of healthy people, and even more so in older individuals than in younger people. Of particular interest was the finding that a major determinant of the blood levels of AGEs is the amount of AGEs in the diet, not dietary calories, sugar, or fat. The study, which was done in collaboration with, and supported by, the National Institute on Aging (NIA), is published in the April issue of the Journal of Gerontology: Medical Sciences.
"AGEs are quite deceptive, since they also give our food desirable tastes and smells," says Helen Vlassara, MD, senior study author, Director of the Division of Experimental Diabetes and Aging, and Professor of Medicine and Geriatrics at Mount Sinai School of Medicine. "So, consuming high amounts of grilled, broiled, or fried food means consuming significant amounts of AGEs, and AGEs in excess are toxic. People should be given information about their AGE intake and be advised to consider their intake in the same way they would think about their trans fats and salt intake. They should be warned about their AGE levels the way they are about their cholesterol levels or cigarette smoking."_
Inflammation and oxidative stress are more common in older age, so the goal of the study was to assess whether AGEs played a significant role in age-related inflammation and oxidative stress by measuring AGE levels in both young and older individuals. The study involved 172 healthy men and women who were divided into two age groups—those between the ages of 18 and 45 and those between the ages of 60 and 80. Dr. Vlassara and her team also wanted to assess whether AGE levels correlated with dietary intake. To do this, her team recorded the patient’s body weight, body fat, three-day dietary information, and collected blood samples to measure biomarkers of inflammation, such as C-reactive protein (CRP). Blood samples were used to test for two common AGEs, called carboxymethyllysine (CML) and methylglyoxal (MG), which latch on to proteins and fats.
The blood tests showed that AGE levels were 35 percent higher in individuals age 65 and older compared with those younger than age 45. The study also showed that in all of the participants, the higher the consumption of foods rich in AGEs, the higher the blood levels of AGEs, and higher the levels of CRP and other markers of inflammation.
Much to the researchers’ surprise, the study also showed that AGE levels could be very high in young healthy people. In fact, high AGE levels found in some healthy adults in this study were on par with AGE levels observed in diabetic patients in their earlier studies. The fact that healthy adults had levels similar to those seen in diabetic patients may suggest that early and prolonged exposure to these substances in the diet could accelerate the onset of diseases. Dr. Vlassara notes that the availability and consumption of AGE-rich foods is high and correlates with rising rates of diabetes and heart disease.
"Excessive intake of fried, broiled, and grilled foods can overload the body’s natural capacity to remove AGEs," Dr. Vlassara notes, "so they accumulate in our tissues, and take over the body’s own built-in defenses, pushing them toward a state of inflammation. Over time, this can precipitate disease or early aging." Once AGEs enter the body, it becomes more difficult to get them out, especially as people age. Older people have a reduced capacity for removing AGEs from the body, the researchers explain, most likely because kidney function slows down as the body ages.
As Dr. Vlassara cautions, "although the accumulation of AGEs pose an immediate and significant health threat to the older adult population, they are also an invisible, lingering danger especially for younger people and this needs to be addressed. AGE levels should be shown on nutrition labels so everyone is aware of them when buying or preparing meals – and our studies explain why."
A Simple Solution: Steam, Boil, Stew
Despite the ubiquity of AGEs, Dr. Vlassara and her team offer simple, safe, and economic solutions that echo the recommendations given concerning trans fats—watch what you eat. New methods of cooking to reduce AGE intake, particularly steaming, boiling or making stews, can make a difference. "Keeping the heat down and maintaining the water content in food reduces AGE levels," Dr. Vlassara says. A 50 percent reduction in AGE intake could have a significant and positive impact on overall health and may even help extend one’s lifespan, according to Dr. Vlassara. In other studies, the team has found that cutting AGE intake in half, but maintaining a diet comprised of the same calories and fat, increased the lifespan of animals when compared with animals fed their usual diet.
At the moment, changing one’s approaches to cooking is the only defense against excessive AGE consumption. There is no routine clinical test to inform individuals of their blood or dietary AGE levels nor established treatment to reduce high AGE blood levels. "The concept that food-related AGE intake is harmful is new to the general public," says Dr. Vlassara, "and scientists are now seeing how AGE intake fits with the current trends of disease epidemics. Hopefully, these wake-up signals, together with other gathering evidence at the cellular and molecular level, will accelerate our efforts to develop effective measures against excessive dietary AGEs. This issue, however, should be dealt with as an important health hazard now, rather than later."
Tips for Safer Grilling
Ruining a piece of meat isn’t the only thing you need to worry about if you’re cooking at high temperatures. High heat can also produce chemicals with cancer-causing properties, reports the June 2007 issue of the Harvard Health Letter.
When meat is cooked at high temperatures, amino acids react with creatine to form heterocyclic amines, which are thought to cause cancer. That’s why cooking meat by grilling, frying, or broiling is the problem. Grilling is double trouble because it also exposes meat to cancer-causing chemicals contained in the smoke that rises from burning coals and any drips of fat that cause flare-ups. How long the meat is cooked is also a factor in heterocyclic amine formation; longer cooking time means more heterocyclic amines. Depending on the temperature at which it’s cooked, meat roasted or baked in the oven may contain some heterocyclic amines, but it’s likely to be considerably less than in grilled, fried, or broiled meat.
Marinating meat is often suggested as one way to cut down on the formation of heterocyclic amines, but the evidence that marinating helps is mixed. The Harvard Health Letter suggests some other tips that may make grilled meat safer to eat:
• Cook smaller pieces: They cook more quickly and at lower temperatures.
• Choose leaner meat: Less fat should reduce flames and therefore smoke.
• Precook in the microwave: Doing so for two minutes may decrease heterocyclic amines by 90%, according to some research.
• Flip frequently: That way, neither side has time to absorb or lose too much heat.
Boiling Vegetables Ruins Benefits
Researchers at the University of Warwick have found that the standard British cooking habit of boiling vegetables severely damages the anticancer properties of many Brassica vegetables such as broccoli, Brussel sprouts, cauliflower and green cabbage.
Past studies have shown that consumption of Brassica vegetables decreases the risk of cancer. This is because of the high concentration in Brassicas of substances known as glucosinolates which are metabolized to cancer preventive substances known as isothiocyanates. However before this research it was not known how the glucosinolates and isothiocyanates were influenced by storage and cooking of Brassica vegetables.
The researchers, Prof Paul Thornalley from Warwick Medical School at the University of Warwick and Dr Lijiang Song from the University of Warwick’s Department of Chemistry bought Brassica vegetables, (broccoli, Brussel sprouts, cauliflower and green cabbage) from a local store and transported them to the laboratory within 30 minutes of purchasing. The effect of cooking on the glucosinolate content of vegetables was then studied by investigating the effects of cooking by boiling, steaming, microwave cooking and stir-fry.
Boiling appeared to have a serious impact on the retention of those important glucosinolate within the vegetables. The loss of total glucosinolate content after boiling for 30 minutes was: broccoli 77%, Brussel sprouts 58%, cauliflower 75% and green cabbage 65%.
The effects of other cooking methods were investigated: steaming for 0–20 min, microwave cooking for 0–3 min and stir-fry cooking for 0–5 min. All three methods gave no significant loss of total glucosinolate analyte contents over these cooking periods._
Domestic storage of the vegetables at ambient temperature and in a domestic refrigerator showed no significant difference with only minor loss of glucosinolate levels over 7 days._
However the researchers found that storage of fresh vegetables at much lower temperatures such as _85 °C (much higher than for storage in a refrigerator at 4–8 °C) may cause significant loss of glucosinolates up to 33% by fracture of vegetable material during thawing._
The researchers found that preparation of Brassica vegetables had caused only minor reductions in glucosinolate except when they were shredded finely which showed a marked decline of glucosinolate levels with a loss of up to 75% over 6 hours after shredding._
Professor Thornalley said: "If you want to get the maximum benefit from your five portions-a-day vegetable consumption, if you are cooking your vegetables boiling is out. You need to consider stir frying, steaming or micro-waving them."
Mediterranean Diet Associated with Lower Risk of Cognitive Impairment
Eating a Mediterranean diet appears to be associated with less risk of mild cognitive impairment—a stage between normal aging and dementia—or of transitioning from mild cognitive impairment into Alzheimer’s disease, according to a report in the February issue of Archives of Neurology, one of the JAMA/Archives journals.
“Among behavioral traits, diet may play an important role in the cause and prevention of Alzheimer’s disease,” the authors write as background information in the article. Previous studies have shown a lower risk for Alzheimer’s disease among those who eat a Mediterranean diet, characterized by high intakes of fish, vegetables, legumes, fruits, cereals and unsaturated fatty acids, low intakes of dairy products, meat and saturated fats and moderate alcohol consumption.
Nikolaos Scarmeas, M.D., and colleagues at Columbia University Medical Center, New York, calculated a score for adherence to the Mediterranean diet among 1,393 individuals with no cognitive problems and 482 patients with mild cognitive impairment. Participants were originally examined, interviewed, screened for cognitive impairments and asked to complete a food frequency questionnaire between 1992 and 1999.
Over an average of 4.5 years of follow-up, 275 of the 1,393 who did not have mild cognitive impairment developed the condition. Compared with the one-third who had the lowest scores for Mediterranean diet adherence, the one-third with the highest scores for Mediterranean diet adherence had a 28 percent lower risk of developing mild cognitive impairment and the one-third in the middle group for Mediterranean diet adherence had a 17 percent lower risk.
Among the 482 with mild cognitive impairment at the beginning of the study, 106 developed Alzheimer’s disease over an average 4.3 years of follow-up. Adhering to the Mediterranean diet also was associated with a lower risk for this transition. The one-third of participants with the highest scores for Mediterranean diet adherence had 48 percent less risk and those in the middle one-third of Mediterranean diet adherence had 45 percent less risk than the one-third with the lowest scores.
The Mediterranean diet may improve cholesterol levels, blood sugar levels and blood vessel health overall, or reduce inflammation, all of which have been associated with mild cognitive impairment. Individual food components of the diet also may have an influence on cognitive risk. “For example, potentially beneficial effects for mild cognitive impairment or mild cognitive impairment conversion to Alzheimer’s disease have been reported for alcohol, fish, polyunsaturated fatty acids (also for age-related cognitive decline) and lower levels of saturated fatty acids,” they write.
Mediterranean Diet May Help Prevent Prostate Cancer
We recently reviewed evidence relating diet and prostate cancer, suggesting that a traditional Cretan Mediterranean style diet based on a variety of plant foods (fruits, vegetables, wholegrain cereals, nuts and legumes), olive oil as the main source of fat, low intake of red meat, moderate to low intake of dairy foods, moderate to high intake of fish and moderate intake of wine, mostly consumed with meals, may be helpful in reducing prostate cancer risk.
Importantly, the Mediterranean diet has other health benefits that further support its widespread adoption. A recent meta-analysis of prospective cohort studies using an a priori score to assess adherence to a Mediterranean diet found that stronger adherence was associated with reduced all cause, cardiovascular and cancer mortality, as well as decreased incidence of Parkinson’s and Alzheimer’s diseases (1).
Two intervention studies have supported the benefits of a Mediterranean style diet on metabolic risk factors (2) (3). In a Spanish study, men and women with elevated levels of cardiovascular risk factors were randomized to either of two “Mediterranean” diets and provided with either olive oil or nuts, or to a control low fat diet. After 3 months the Mediterranean diet groups had lower mean plasma glucose, systolic blood pressure and total/HDL cholesterol ratio than the control group (2). Italian adults with the Metabolic Syndrome were randomized to a “Mediterranean” diet or a “prudent” diet, both with similar macronutrient composition. The “Mediterranean” diet was associated with greater improvements in markers of vascular risk and endothelial function than the control group (3). It should be noted however that in both studies the “Mediterranean” diet groups received more nutrition education than the control groups.
The Lyon Heart Study demonstrated that a modified Cretan diet low in butter and meats, and high in fish, fruits and enriched with _-linolenic acid from canola oil was more effective than a ‘prudent’ diet in the secondary prevention of coronary events and overall mortality (4). We have also shown that a Cretan style diet reduced HbA1c from a mean of 7.1% (95% CI: 6.5-7.7) to 6.8% (95% CI: 6.3-7.3) (p=0.012), in people with type 2 diabetes (unpublished data).
Simopoulos (5) notes that the traditional Greek diet resembles the Paleolithic diet in terms of fibre, antioxidants, saturated and monounsaturated fat, thus is consistent with human evolution. While traditional diets must reflect the regionally available foods, the characteristics of the traditional Greek diet can be applied in many countries, notwithstanding the likely effect of environment and growing methods on the nutrient composition of plant and animal foods. The evidence suggests that a traditional Greek or Cretan style diet is consistent with what humans have evolved to consume and may protect against common chronic diseases, including prostate cancer.
References:
1. Sofi F, Cesari F, Abbate R, Gensini GF, Casini A. Adherence to Mediterranean diet and health status: meta-analysis. Bmj 2008;337:a1344._2. Estruch R, Martinez-Gonzalez MA, Corella D, et al. Effects of a Mediterranean-style diet on cardiovascular risk factors: a randomized trial. Ann Intern Med 2006;145:1-11._3. Esposito K, Marfella R, Ciotola M, et al. Effect of a Mediterranean-style diet on endothelial dysfunction and markers of vascular inflammation in the metabolic syndrome: a randomized trial. J Am Med Assoc 2004;292:1440-6._4. de Lorgeril M, Salen P. Modified Cretan Mediterranean diet in the prevention of coronary heart disease and cancer. In: Simopoulos AP, Visioli F, eds. Mediterranean Diets. World Review Nutr Diet. Basel: Karger, 2000:1-23._5. Simopoulos AP. The traditional diet of Greece and cancer. Eur J Cancer Prev 2004;13:219-30.
Mediterranean diet wards off childhood respiratory allergies
Protective effect of fruits, vegetables and the Mediterranean diet on asthma and allergies among children in Crete.
"Mediterranean" diet rich in fruits, vegetables and nuts protects against allergic rhinitis and asthma symptoms, suggests research published ahead of print in Thorax.
The researchers assessed the dietary habits, respiratory symptoms, and allergic reactions of almost 700 children living in four rural areas on the Greek island of Crete.
The children were all aged between 7 and 18 years of age.
Skin allergies are relatively common in Crete, but respiratory allergies, such as asthma and allergic rhinitis are relatively rare.
Parents completed detailed questionnaires on their children's allergic and respiratory symptoms and dietary habits.
Whether the children ate a "Mediterranean" diet was measured against a set of 12 foodstuffs, including fruits, vegetables, whole-grains, legumes, nuts, and olive oil.
Eight out of 10 children ate fresh fruit, and over two thirds of them ate fresh vegetables, at least twice a day.
The effect of diet was strongest on allergic rhinitis, but it also afforded protection against asthma symptoms and skin allergy.
Children who ate nuts at least three times a week were less likely to wheeze.
Nuts are a rich source of vitamin E, the body's primary defence against cellular damage caused by free radicals. And they contain high levels of magnesium, which other research suggests, may protect against asthma and boost lung power.
And a daily diet of oranges, apples, and tomatoes also protected against wheezing and allergic rhinitis.
Grapes in particular seemed to protect against current and previous wheezing and allergic rhinitis, even after adjusting for other potentially influential factors.
Red grape skin contains high levels of antioxidants as well as resveratrol, a potent polyphenol, known to curb inflammatory activity, say the authors.
But high consumption of margarine doubled the chances of asthma and allergic rhinitis, the findings showed.
Adherence to the Mediterranean food pattern helps
Adherence to the Mediterranean food pattern predicts the prevalence of hypertension, hypercholesterolemia, diabetes and obesity, among healthy adults.
A diet score (range 0–55) has been developed that assesses adherence to the Mediterranean diet. For the consumption of items presumed to be close to Mediterranean dietary pattern (non-refined cereals, fruits, vegetables, legumes, olive oil, fish and potatoes) scores 0 to 5 for never, rare, frequent, very frequent, weekly and daily consumption were assigned, while for the consumption of foods presumed to be away from this pattern (red meat and products, poultry and full fat dairy products) scores on a reverse scale were assigned.
The Mediterranean diet was a strong predictor of non-occurence of these diseases.
Mediterranean Diet Halves Risk of Lung Disease
A Mediterranean diet halves the chances of developing progressive inflammatory lung disease (COPD), reveals a large study, published ahead of print in Thorax.
COPD (chronic obstructive pulmonary disease) is an umbrella term for chronic progressive lung disease, such as emphysema and bronchitis. It is expected to become the third leading cause of death worldwide by 2020, with cigarette smoking the primary factor in its development.
The researchers tracked the health of almost 43,000 men, who were already part of the US Health Professionals Follow up Study. This began in 1986 and involved more than 50,000 US health care professionals aged between 40 and 75, who were surveyed every two years.
They were asked questions about lifestyle, including smoking and exercise, diet and medical history. Dietary intake was assessed in detail every four years.
Eating patterns fell into two distinct categories: those who ate a diet rich in fruit, vegetables, whole grains and fish (Mediterranean diet); and those who ate a diet rich in processed foods, refined sugars, and cured and red meats (Western diet).
Between 1986 and 1998, 111 cases of COPD were newly diagnosed.
The Mediterranean diet was associated with a 50% lower risk of developing COPD than the Western diet, even after adjusting for age, smoking, and other risk factors.
And men who ate a predominantly Western diet were more than four times as likely to develop COPD, even after taking account of other influential factors.
The higher the compliance with a Mediterranean diet, the lower was the risk of developing COPD over the 12 year period.
Conversely, the higher the compliance with the Western diet, the higher was the risk of developing COPD.
Mediterranean diet and physical activity each associated with lower death rate over 5 years
Eating a Mediterranean diet and following national recommendations for physical activity are each associated with a reduced risk of death over a five-year period, according to two reports in the December 10/24 issue of Archives of Internal Medicine, one of the JAMA/Archives journals. Both studies use data from the National Institutes of Health-AARP Diet and Health Study, which began when questionnaires were returned from 566,407 AARP members age 50 to 71 in six states between 1995 and 1996.
In one study, Panagiota N. Mitrou, Ph.D., then of the National Cancer Institute, Bethesda, Md., and now of the University of Cambridge, England, and colleagues used a nine-point scale to assess conformity with the Mediterranean diet in 380,296 of the participants (214,284 men and 166,012 women) with no history of chronic disease. Components of the diet included vegetables, legumes, fruits, nuts, whole grains, fish, ratio of monounsaturated fats, alcohol and meat. During five years of follow-up, 12,105 participants died, including 5,985 from cancer and 3,451 from cardiovascular disease. Those with higher Mediterranean diet scores were less likely to die of any cause or of cancer or heart disease.
Fruit and vegetable intake and head and neck cancer
Fruit and vegetable intake and head and neck cancer in a large United States prospective cohort study: Abstract 849
A new study among AARP members shows that just one additional serving of fruit and vegetables per day may lower your risk of head and neck cancer, but the data suggest that you may not want to stop at just one, according to researchers from the National Cancer Institute.
A large prospective study of 500,000 men and women aged 50 and older has found that those who ate more fruit and vegetables had a reduced risk of head and neck cancer. Head and neck cancer is the sixth leading cause of cancer-related mortality worldwide, resulting in more than 350,000 deaths annually.
"Identifying protective factors for head and neck cancer is particularly important as it has a high mortality rate," said Neal Freedman, Ph.D., cancer prevention fellow at the National Cancer Institute.
At the beginning of the study, participants reported their typical dietary habits on a food frequency questionnaire. Freedman and his colleagues followed participants for five years and recorded all diagnoses of head and neck cancer cases during this time.
In their findings, the researchers report that participants who ate six servings of fruit and vegetables per day per 1000 calories had 29 percent less risk for head and neck cancer than did participants who consumed one and a half servings per 1000 calories per day. Typically, adults consume approximately 2000 calories per day. One serving equals approximately one medium sized fresh fruit, one half cup of cut fruit, six ounces fruit juice, one cup leafy vegetables, or one half cup of other vegetables.
"Increasing consumption by just one serving of fruit or vegetables per 1000 calories per day was associated with a six percent reduction in head and neck cancer risk," Freedman said.
According to Freedman, people who ate a lot of fruit also tended to eat a lot of vegetables, and vice versa. To measure these two types of foods independently, the researchers included both fruit and vegetable intake in the statistical models, a common statistical approach. This allowed them to compare participants with different levels of fruit consumption while holding constant the level of vegetable intake and vice versa. When examining fruit and vegetable intake simultaneously, the protective association with vegetables seemed to be stronger than the association with fruits.
"Although we cannot absolutely rule out a cancer preventive role for other lifestyle factors that go along with eating more fruits and vegetables, our results are consistent with those from previous studies," Freedman said. "Our study suggests that fruit and vegetable consumption may protect against head and neck cancer and adds support to current dietary recommendations to increase fruit and vegetable consumption."
Flavonols and pancreatic cancer risk
A study of food consumption in 183,518 residents of California and Hawaii has found that a diet high in flavonols might help reduce pancreatic cancer risk, especially in smokers. These compounds are generally ubiquitous in plant-based foods, but are found in highest concentrations in onions, apples, berries, kale and broccoli.
People who ate the largest amounts of flavonols had a 23 percent reduced risk of developing pancreatic cancer compared to those who ate the least, according to a research team led by Laurence Kolonel, M.D., Ph.D., at the Cancer Research Center of Hawaii.
Smokers gained the most benefit. Those who ate the most flavonols reduced their risk of developing pancreatic cancer by 59 percent, compared to those who ate the least, says the study’s lead author, Ute Nöthlings, DrPH, who conducted the study as a postdoctoral fellow in Hawaii and is now a researcher at the German Institute of Human Nutrition Potsdam-Rehbruecke.
‘The effect was largest in smokers, presumably because they are at increased pancreatic cancer risk already," said Nöthlings. Smoking is the only established risk factor for pancreatic cancer, and "short of stopping tobacco use, it has been difficult to consistently show lifestyle factors that might help protect against this deadly cancer," she says.
As part of a larger research project known as The Multiethnic Cohort Study, Kolonel and Nöthlings followed the participants for an average of eight years after they filled out a comprehensive food questionnaire.
Although Nöthlings says the study has a large statistical power because of the large number of pancreatic cancer cases (529) that occurred in the study population, she says that this one study cannot firmly answer the question of whether flavonols can prevent development of pancreatic cancer. "Further epidemiological studies in other populations and geographic regions are needed to confirm our findings," she said.
The study also is the first to examine prospectively specific classes of flavonols and pancreatic cancer risk.
The researchers looked at consumption of three flavonols: quercetin, which is most abundant in onions and apples; kaempferol, found in spinach and some cabbages; and myricetin, found mostly in red onions and berries.
Of the three individual flavonols, kaempferol was associated with the largest risk reduction (22 percent) across all participants. When the researchers divided intake into quartiles, and then compared highest intake to lowest, all the three classes of flavonols were associated with a significant trend toward reduced pancreatic cancer risk in current smokers, but not in never or former smokers. The interaction with smoking status was statistically significant for total flavonols, quercetin and kaempferol.
The researchers say their study did not examine the biological mechanisms by which these flavonols could exert a protective effect against pancreatic cancer. "But anti-carcinogenic effects of flavonoids in general have been attributed to the ability of these constituents to inhibit cell cycle, cell proliferation and oxidative stress, and to induce detoxification enzymes and apoptosis," Nöthlings said.
Studies Force New View on Biology, Nutritional Action of Flavonoids
Flavonoids, a group of compounds found in fruits and vegetables that had been thought to be nutritionally important for their antioxidant activity, actually have little or no value in that role, according to an analysis by scientists in the Linus Pauling Institute at Oregon State University.
However, these same compounds may indeed benefit human health, but for reasons that are quite different – the body sees them as foreign compounds, researchers say, and through different mechanisms, they could play a role in preventing cancer or heart disease.
Based on this new view of how flavonoids work, a relatively modest intake of them – the amount you might find in a healthy diet with five to nine servings of fruits and vegetables – is sufficient. Large doses taken via dietary supplements might do no additional good; an apple a day may still be the best bet.
A research survey, and updated analysis of how flavonoids work and function in the human body, were recently published in Free Radical Biology and Medicine, a professional journal.
“What we now know is that flavonoids are highly metabolized, which alters their chemical structure and diminishes their ability to function as an antioxidant,” said Balz Frei, professor and director of the Linus Pauling Institute. “The body sees them as foreign compounds and modifies them for rapid excretion in the urine and bile.”
Flavonoids are polyphenolic compounds with some common characteristics that are widely found in fruits and vegetables and often give them their color – they make lemons yellow and certain apples red. They are also found in some other foods, such as coffee, tea, wine, beer and chocolate, and studies in recent years had indicated that they had strong antioxidant activity – and because of that, they might be important to biological function and health.
“If you measure the activity of flavonoids in a test tube, they are indeed strong antioxidants,” Frei said. “Based on laboratory tests of their ability to scavenge free radicals, it appears they have 3-5 times more antioxidant capacity than vitamins C or E. But with flavonoids in particular, what goes on in a test tube is not what’s happening in the human body.”
Research has now proven that flavonoids are poorly absorbed by the body, usually less than five percent, and most of what does get absorbed into the blood stream is rapidly metabolized in the intestines and liver and excreted from the body. By contrast, vitamin C is absorbed 100 percent by the body up to a certain level. And vitamin C accumulates in cells where it is 1,000 to 3,000 times more active as an antioxidant than flavonoids.
The large increase in total antioxidant capacity of blood observed after the consumption of flavonoid-rich foods is not caused by the flavonoids themselves, Frei said, but most likely is the result of increased uric acid levels.
But just because flavonoids have been found to be ineffectual as antioxidants in the human body does not mean they are without value, Frei said. They appear to strongly influence cell signaling pathways and gene expression, with relevance to both cancer and heart disease.
“We can now follow the activity of flavonoids in the body, and one thing that is clear is that the body sees them as foreign compounds and is trying to get rid of them,” Frei said. “But this process of gearing up to get rid of unwanted compounds is inducing so-called Phase II enzymes that also help eliminate mutagens and carcinogens, and therefore may be of value in cancer prevention.
“Flavonoids could also induce mechanisms that help kill cancer cells and inhibit tumor invasion,” Frei added.
It also appears that flavonoids increase the activation of existing nitric oxide synthase, which has the effect of keeping blood vessels healthy and relaxed, preventing inflammation, and lowering blood pressure – all key goals in prevention of heart disease.
Both of these protective mechanisms could be long-lasting compared to antioxidants, which are more readily used up during their free radical scavenging activity and require constant replenishment through diet, scientists say.
However, Frei said, it’s also true that such mechanisms require only relatively small amounts of flavonoids to trigger them – conceptually, it’s a little like a vaccine in which only a very small amount of an offending substance is required to trigger a much larger metabolic response. Because of this, there would be no benefit – and possibly some risk – to taking dietary supplements that might inject large amounts of substances the body essentially sees as undesirable foreign compounds.
Numerous studies in the United States and Europe have documented a relationship between adequate dietary intake of flavonoid-rich foods, mostly fruits and vegetables, and protection against heart disease, cancer and neurodegenerative disease, Frei said.
FRESH VEGETABLES, FRUITS REDUCE DIABETES RISK
Eating just one more serving of green leafy vegetables or three more servings of fruit a day reduces the risk of developing Type II diabetes, according to results of data analysis performed by researchers in the Tulane School of Public Health and Tropical Medicine and the Harvard School of Public Health. The research team also found that one serving of fruit juice a day increased the risk of Type II diabetes in women.
Tulane epidemiologist Dr. Lydia Bazzano says, “Based on the results of our study, people who have risk factors for diabetes may find it helpful to fill up on leafy greens like lettuces, kale and spinach and whole fruits, like apples, bananas, oranges and watermelon rather than drink fruit juices, which deliver a big sugar load in a liquid form that gets absorbed rapidly.”
Bazzano, an assistant professor of epidemiology, cautioned that since this is one of the first studies to separate fruit juice consumption from fruits as a whole, the association between juice and diabetes must be confirmed by additional research.
She and her team analyzed 18 years worth of diet and health data from 71,346 nurses who participated in the Nurses’ Health Study from 1984 to 2002. The women were all between 38 and 63 years old and diabetes-free when the study began. Approximately 7 percent of the participants developed diabetes over the course of the study.
The researchers determined that the association between fruit and green leafy vegetable consumption and lowered diabetes risk remained after other factors, such as family history, cigarette smoking and weight, were analyzed. However, they found that women who ate more fruits and green leafy vegetables also were likely to be older, non-smokers and more physically active.
In addition to emphasizing the importance of eating whole fruits and green leafy vegetables to prevent diabetes, the team also recommends replacing refined grains and white potatoes with whole fruit or green leafy vegetable servings. White flours and potatoes have been associated with an increased risk of diabetes.
“Western” diet increases heart attack risk globally
The typical Western diet — fried foods, salty snacks and meat — accounts for about 30 percent of heart attack risk across the world, according to a study of dietary patterns in 52 countries reported in Circulation: Journal of the American Heart Association.
Researchers identified three dietary patterns in the world:
• Oriental: higher intake of tofu, soy and other sauces;
• Prudent: higher intake of fruits and vegetables; and
• Western: higher intake of fried foods, salty snacks, eggs and meat.
The Prudent diet was associated with a lower heart attack risk than the Oriental, researchers said.
“The objective of this study was to understand the modifiable risk factors of heart attacks at a global level,” said Salim Yusuf, D.Phil., the study’s senior author.
Previous studies have reached similar conclusions about the Prudent and Western diet in the United States and Europe. This study broadens those findings and identifies a unique dietary pattern that researchers labeled “Oriental” (because of a higher content of food items typical of an Oriental diet.) The dietary pattern recommended by the American Heart Association is similar to the Prudent diet described in this study.
“This study indicates that the same relationships that are observed in Western countries exist in different regions of the world,” said Yusuf, professor of medicine at McMaster University and director of the Population Health Research Institute at Hamilton Health Sciences in Ontario, Canada.
Researchers analyzed the INTERHEART study, which documents the association of various risk factors and the risk of heart attack in about 16,000 participants in 52 countries. Here, they analyzed 5,761 heart attack cases and compared them to 10,646 people without known heart disease (controls).
The researchers created a dietary risk score questionnaire for heart attacks patients, based on 19 food groups and adjusted it for dietary preferences for each country. Trained medical personnel interviewed the heart attack patients and the control group. The questionnaires included healthy food items (such as fruits and vegetables) and unhealthy food items (such as fried foods and salty snacks).
“A simple dietary score, which included both good and bad foods with the higher score indicating a worse diet, showed that 30 percent of the risk of heart disease in a population could be related to poor diet,” said Romania Iqbal, Ph.D., lead author of the study.
After adjusting for known risk factors, researchers found:
• People who consumed the Prudent diet of more fruits and vegetables had a 30 percent lower risk of heart attack compared to people who ate little or no fruits and vegetables.
• People who consumed the Western diet had a 35 percent greater risk of having a heart attack compared to people who consumed little or no fried foods and meat.
• The Oriental pattern showed no relationship with heart attack risk.
Researchers said that while some components of the Oriental pattern may be protective, others such as the higher sodium content of soy sauces, may increase cardiovascular risk, neutralizing any relationship.
It’s expensive and time-consuming to establish a large and long-term study examining the relationship of diet and heart attack in every region of the world. So the approach of this study is the only feasible way to examine the relationship to diet and heart disease from multiple populations in a relatively short time at an affordable cost, Yusuf said.
Data from this study helped confirm that changes in dietary intake, including the consumption of more fruits and vegetables, can help reduce the risk of having a heart attack in populations worldwide, he said.
“At the same time, an unhealthy dietary intake, assessed by a simple dietary risk score, accounts for nearly one-third of the world population’s attributable risk,” Yusuf said.
French Fries and Potato Chips Are Dangerous
A new study published in the March 2009 American Journal of Clinical Nutrition by Marek Naruszewicz and colleagues from Poland suggests that acrylamide from foods may increase the risk of heart disease. Acrylamide has been linked previously to nervous system disorders and possibly to cancer. After ingesting large amounts of potato chips providing about 157 micrograms of acrylamide daily for four weeks, the participants had adverse changes in oxidized LDL, inflammatory markers and antioxidants that help the body eliminate acrylamide—all of which may increase the risk of heart disease. Additional research is needed in long-term studies of people consuming typical amounts of acrylamide (averaging about 20 to 30 micrograms).
It is recommended that FDA and the food industry continue to decrease acrylamide in foods by improving food processing technologies. FDA reports that acrylamide is particularly high in potato chips and French fries (http://www.cfsan.fda.gov/~dms/acrydata.html). According to American Society for Nutrition Spokesperson Mary Ann Johnson, PhD: "Consumers can reduce their exposure to acrylamide by limiting their intake of potato chips and French fries, choosing a variety of fruits, vegetables, whole grains, and low fat meat and dairy products, and quitting smoking, which is a major source of acrylamide."
Eating red meat sets up target for disease-causing bacteria
Non-human molecules absorbed by eating red meat increase risk of food poisoning in humans
Offering another reason why eating red meat could be bad for you, an international research team, including University of California, San Diego School of Medicine professor Ajit Varki, M.D., has uncovered the first example of a bacterium that causes food poisoning in humans when it targets a non-human molecule absorbed into the body through red meats such as lamb, pork and beef.
In findings to be published on line October 29th in advance of print in the journal Nature, the scientists discovered that a potent bacterial toxin called subtilase cytotoxin specifically targets human cells that have a non-human, cellular molecule on their surface. The molecule –N-glycolylneuraminic acid (Neu5Gc) – is a type of glycan, or sugar molecule, that humans don't naturally produce.
Subtilase cytotoxin is produced by certain kinds of E. coli bacteria, causing bloody diarrhea and a potentially fatal disease called haemolytic uraemic syndrome (HUS) in humans. Humans usually become infected after eating contaminated red meat, which is why this is also known as "hamburger" disease.
Varki, UC San Diego School of Medicine distinguished professor of medicine and cellular and molecular medicine, and co-director of the UCSD Glycobiology Research and Training Center, previously discovered that humans don't produce Neu5Gc because they lack the gene responsible for its production. Therefore, it was thought that humans should be resistant to the toxin.
"Ironically, humans may set themselves up for an increased risk of illness from this kind of E. coli bacteria present in contaminated red meat or dairy, because these very same products have high-levels of Neu5Gc," Varki explained. "The Neu5Gc molecule is absorbed into the body, making it a target for the toxin produced by E. coli."
In the Nature study, the researchers discovered that sites where the Neu5Gc has been incorporated into the human body coincide with toxin binding. "When the toxin binds to the non-human Neu5Gc receptors, it can result in serious food-poisoning and other symptoms in humans," said Varki. The research emphasizes the need for people to eat only well-cook meat or pasteurized dairy products, processes that destroy contaminating bacteria.
Five years ago, Varki and his colleagues at the UC San Diego School of Medicine published a paper in the Proceedings of the National Academy of Sciences describing how Neu5Gc is absorbed into human tissues – including the surface of cells lining the intestines and blood vessels – as a result of eating red meat and milk products. At the time, the researchers also showed that this foreign molecule generates an immune response that could potentially lead to inflammation in human tissues. The UC San Diego study was the first to investigate human dietary absorption of the Neu5Gc glycans which, while not produced in humans, does occur naturally in red meats. Levels are very low or undetectable in fruits, vegetables, eggs, poultry and fish. The researchers proved that people who ingest Neu5Gc incorporate some of it into their tissues, and demonstrated that many generated an immune response against the molecule, conjecturing that a lifetime of gradual incorporation of this glycan "invader" could result in disease.
Fried, Broiled, Grilled Foods = Bad Health
Study shows food preparation may play a bigger role in chronic disease than was previously thought_
How your food is cooked may be as important to your health as the food itself. Researchers now know more about a new class of toxins that might soon become as important a risk factor for heart disease and metabolic disorders as trans fats.
This class of toxins, called advanced glycation end products (AGEs), are absorbed into the body through the consumption of grilled, fried, or broiled animal products, such as meats and cheeses. AGEs, which are also produced when food products are sterilized and pasteurized, have been linked to inflammation, insulin resistance, diabetes, vascular and kidney disease, and Alzheimer’s disease.
A new study at Mount Sinai School of Medicine reveals that AGE levels are elevated in the blood of healthy people, and even more so in older individuals than in younger people. Of particular interest was the finding that a major determinant of the blood levels of AGEs is the amount of AGEs in the diet, not dietary calories, sugar, or fat. The study, which was done in collaboration with, and supported by, the National Institute on Aging (NIA), is published in the April issue of the Journal of Gerontology: Medical Sciences.
"AGEs are quite deceptive, since they also give our food desirable tastes and smells," says Helen Vlassara, MD, senior study author, Director of the Division of Experimental Diabetes and Aging, and Professor of Medicine and Geriatrics at Mount Sinai School of Medicine. "So, consuming high amounts of grilled, broiled, or fried food means consuming significant amounts of AGEs, and AGEs in excess are toxic. People should be given information about their AGE intake and be advised to consider their intake in the same way they would think about their trans fats and salt intake. They should be warned about their AGE levels the way they are about their cholesterol levels or cigarette smoking."_
Inflammation and oxidative stress are more common in older age, so the goal of the study was to assess whether AGEs played a significant role in age-related inflammation and oxidative stress by measuring AGE levels in both young and older individuals. The study involved 172 healthy men and women who were divided into two age groups—those between the ages of 18 and 45 and those between the ages of 60 and 80. Dr. Vlassara and her team also wanted to assess whether AGE levels correlated with dietary intake. To do this, her team recorded the patient’s body weight, body fat, three-day dietary information, and collected blood samples to measure biomarkers of inflammation, such as C-reactive protein (CRP). Blood samples were used to test for two common AGEs, called carboxymethyllysine (CML) and methylglyoxal (MG), which latch on to proteins and fats.
The blood tests showed that AGE levels were 35 percent higher in individuals age 65 and older compared with those younger than age 45. The study also showed that in all of the participants, the higher the consumption of foods rich in AGEs, the higher the blood levels of AGEs, and higher the levels of CRP and other markers of inflammation.
Much to the researchers’ surprise, the study also showed that AGE levels could be very high in young healthy people. In fact, high AGE levels found in some healthy adults in this study were on par with AGE levels observed in diabetic patients in their earlier studies. The fact that healthy adults had levels similar to those seen in diabetic patients may suggest that early and prolonged exposure to these substances in the diet could accelerate the onset of diseases. Dr. Vlassara notes that the availability and consumption of AGE-rich foods is high and correlates with rising rates of diabetes and heart disease.
"Excessive intake of fried, broiled, and grilled foods can overload the body’s natural capacity to remove AGEs," Dr. Vlassara notes, "so they accumulate in our tissues, and take over the body’s own built-in defenses, pushing them toward a state of inflammation. Over time, this can precipitate disease or early aging." Once AGEs enter the body, it becomes more difficult to get them out, especially as people age. Older people have a reduced capacity for removing AGEs from the body, the researchers explain, most likely because kidney function slows down as the body ages.
As Dr. Vlassara cautions, "although the accumulation of AGEs pose an immediate and significant health threat to the older adult population, they are also an invisible, lingering danger especially for younger people and this needs to be addressed. AGE levels should be shown on nutrition labels so everyone is aware of them when buying or preparing meals – and our studies explain why."
A Simple Solution: Steam, Boil, Stew
Despite the ubiquity of AGEs, Dr. Vlassara and her team offer simple, safe, and economic solutions that echo the recommendations given concerning trans fats—watch what you eat. New methods of cooking to reduce AGE intake, particularly steaming, boiling or making stews, can make a difference. "Keeping the heat down and maintaining the water content in food reduces AGE levels," Dr. Vlassara says. A 50 percent reduction in AGE intake could have a significant and positive impact on overall health and may even help extend one’s lifespan, according to Dr. Vlassara. In other studies, the team has found that cutting AGE intake in half, but maintaining a diet comprised of the same calories and fat, increased the lifespan of animals when compared with animals fed their usual diet.
At the moment, changing one’s approaches to cooking is the only defense against excessive AGE consumption. There is no routine clinical test to inform individuals of their blood or dietary AGE levels nor established treatment to reduce high AGE blood levels. "The concept that food-related AGE intake is harmful is new to the general public," says Dr. Vlassara, "and scientists are now seeing how AGE intake fits with the current trends of disease epidemics. Hopefully, these wake-up signals, together with other gathering evidence at the cellular and molecular level, will accelerate our efforts to develop effective measures against excessive dietary AGEs. This issue, however, should be dealt with as an important health hazard now, rather than later."
Tips for Safer Grilling
Ruining a piece of meat isn’t the only thing you need to worry about if you’re cooking at high temperatures. High heat can also produce chemicals with cancer-causing properties, reports the June 2007 issue of the Harvard Health Letter.
When meat is cooked at high temperatures, amino acids react with creatine to form heterocyclic amines, which are thought to cause cancer. That’s why cooking meat by grilling, frying, or broiling is the problem. Grilling is double trouble because it also exposes meat to cancer-causing chemicals contained in the smoke that rises from burning coals and any drips of fat that cause flare-ups. How long the meat is cooked is also a factor in heterocyclic amine formation; longer cooking time means more heterocyclic amines. Depending on the temperature at which it’s cooked, meat roasted or baked in the oven may contain some heterocyclic amines, but it’s likely to be considerably less than in grilled, fried, or broiled meat.
Marinating meat is often suggested as one way to cut down on the formation of heterocyclic amines, but the evidence that marinating helps is mixed. The Harvard Health Letter suggests some other tips that may make grilled meat safer to eat:
• Cook smaller pieces: They cook more quickly and at lower temperatures.
• Choose leaner meat: Less fat should reduce flames and therefore smoke.
• Precook in the microwave: Doing so for two minutes may decrease heterocyclic amines by 90%, according to some research.
• Flip frequently: That way, neither side has time to absorb or lose too much heat.
Boiling Vegetables Ruins Benefits
Researchers at the University of Warwick have found that the standard British cooking habit of boiling vegetables severely damages the anticancer properties of many Brassica vegetables such as broccoli, Brussel sprouts, cauliflower and green cabbage.
Past studies have shown that consumption of Brassica vegetables decreases the risk of cancer. This is because of the high concentration in Brassicas of substances known as glucosinolates which are metabolized to cancer preventive substances known as isothiocyanates. However before this research it was not known how the glucosinolates and isothiocyanates were influenced by storage and cooking of Brassica vegetables.
The researchers, Prof Paul Thornalley from Warwick Medical School at the University of Warwick and Dr Lijiang Song from the University of Warwick’s Department of Chemistry bought Brassica vegetables, (broccoli, Brussel sprouts, cauliflower and green cabbage) from a local store and transported them to the laboratory within 30 minutes of purchasing. The effect of cooking on the glucosinolate content of vegetables was then studied by investigating the effects of cooking by boiling, steaming, microwave cooking and stir-fry.
Boiling appeared to have a serious impact on the retention of those important glucosinolate within the vegetables. The loss of total glucosinolate content after boiling for 30 minutes was: broccoli 77%, Brussel sprouts 58%, cauliflower 75% and green cabbage 65%.
The effects of other cooking methods were investigated: steaming for 0–20 min, microwave cooking for 0–3 min and stir-fry cooking for 0–5 min. All three methods gave no significant loss of total glucosinolate analyte contents over these cooking periods._
Domestic storage of the vegetables at ambient temperature and in a domestic refrigerator showed no significant difference with only minor loss of glucosinolate levels over 7 days._
However the researchers found that storage of fresh vegetables at much lower temperatures such as _85 °C (much higher than for storage in a refrigerator at 4–8 °C) may cause significant loss of glucosinolates up to 33% by fracture of vegetable material during thawing._
The researchers found that preparation of Brassica vegetables had caused only minor reductions in glucosinolate except when they were shredded finely which showed a marked decline of glucosinolate levels with a loss of up to 75% over 6 hours after shredding._
Professor Thornalley said: "If you want to get the maximum benefit from your five portions-a-day vegetable consumption, if you are cooking your vegetables boiling is out. You need to consider stir frying, steaming or micro-waving them."
Mediterranean Diet Associated with Lower Risk of Cognitive Impairment
Eating a Mediterranean diet appears to be associated with less risk of mild cognitive impairment—a stage between normal aging and dementia—or of transitioning from mild cognitive impairment into Alzheimer’s disease, according to a report in the February issue of Archives of Neurology, one of the JAMA/Archives journals.
“Among behavioral traits, diet may play an important role in the cause and prevention of Alzheimer’s disease,” the authors write as background information in the article. Previous studies have shown a lower risk for Alzheimer’s disease among those who eat a Mediterranean diet, characterized by high intakes of fish, vegetables, legumes, fruits, cereals and unsaturated fatty acids, low intakes of dairy products, meat and saturated fats and moderate alcohol consumption.
Nikolaos Scarmeas, M.D., and colleagues at Columbia University Medical Center, New York, calculated a score for adherence to the Mediterranean diet among 1,393 individuals with no cognitive problems and 482 patients with mild cognitive impairment. Participants were originally examined, interviewed, screened for cognitive impairments and asked to complete a food frequency questionnaire between 1992 and 1999.
Over an average of 4.5 years of follow-up, 275 of the 1,393 who did not have mild cognitive impairment developed the condition. Compared with the one-third who had the lowest scores for Mediterranean diet adherence, the one-third with the highest scores for Mediterranean diet adherence had a 28 percent lower risk of developing mild cognitive impairment and the one-third in the middle group for Mediterranean diet adherence had a 17 percent lower risk.
Among the 482 with mild cognitive impairment at the beginning of the study, 106 developed Alzheimer’s disease over an average 4.3 years of follow-up. Adhering to the Mediterranean diet also was associated with a lower risk for this transition. The one-third of participants with the highest scores for Mediterranean diet adherence had 48 percent less risk and those in the middle one-third of Mediterranean diet adherence had 45 percent less risk than the one-third with the lowest scores.
The Mediterranean diet may improve cholesterol levels, blood sugar levels and blood vessel health overall, or reduce inflammation, all of which have been associated with mild cognitive impairment. Individual food components of the diet also may have an influence on cognitive risk. “For example, potentially beneficial effects for mild cognitive impairment or mild cognitive impairment conversion to Alzheimer’s disease have been reported for alcohol, fish, polyunsaturated fatty acids (also for age-related cognitive decline) and lower levels of saturated fatty acids,” they write.
Mediterranean Diet May Help Prevent Prostate Cancer
We recently reviewed evidence relating diet and prostate cancer, suggesting that a traditional Cretan Mediterranean style diet based on a variety of plant foods (fruits, vegetables, wholegrain cereals, nuts and legumes), olive oil as the main source of fat, low intake of red meat, moderate to low intake of dairy foods, moderate to high intake of fish and moderate intake of wine, mostly consumed with meals, may be helpful in reducing prostate cancer risk.
Importantly, the Mediterranean diet has other health benefits that further support its widespread adoption. A recent meta-analysis of prospective cohort studies using an a priori score to assess adherence to a Mediterranean diet found that stronger adherence was associated with reduced all cause, cardiovascular and cancer mortality, as well as decreased incidence of Parkinson’s and Alzheimer’s diseases (1).
Two intervention studies have supported the benefits of a Mediterranean style diet on metabolic risk factors (2) (3). In a Spanish study, men and women with elevated levels of cardiovascular risk factors were randomized to either of two “Mediterranean” diets and provided with either olive oil or nuts, or to a control low fat diet. After 3 months the Mediterranean diet groups had lower mean plasma glucose, systolic blood pressure and total/HDL cholesterol ratio than the control group (2). Italian adults with the Metabolic Syndrome were randomized to a “Mediterranean” diet or a “prudent” diet, both with similar macronutrient composition. The “Mediterranean” diet was associated with greater improvements in markers of vascular risk and endothelial function than the control group (3). It should be noted however that in both studies the “Mediterranean” diet groups received more nutrition education than the control groups.
The Lyon Heart Study demonstrated that a modified Cretan diet low in butter and meats, and high in fish, fruits and enriched with _-linolenic acid from canola oil was more effective than a ‘prudent’ diet in the secondary prevention of coronary events and overall mortality (4). We have also shown that a Cretan style diet reduced HbA1c from a mean of 7.1% (95% CI: 6.5-7.7) to 6.8% (95% CI: 6.3-7.3) (p=0.012), in people with type 2 diabetes (unpublished data).
Simopoulos (5) notes that the traditional Greek diet resembles the Paleolithic diet in terms of fibre, antioxidants, saturated and monounsaturated fat, thus is consistent with human evolution. While traditional diets must reflect the regionally available foods, the characteristics of the traditional Greek diet can be applied in many countries, notwithstanding the likely effect of environment and growing methods on the nutrient composition of plant and animal foods. The evidence suggests that a traditional Greek or Cretan style diet is consistent with what humans have evolved to consume and may protect against common chronic diseases, including prostate cancer.
References:
1. Sofi F, Cesari F, Abbate R, Gensini GF, Casini A. Adherence to Mediterranean diet and health status: meta-analysis. Bmj 2008;337:a1344._2. Estruch R, Martinez-Gonzalez MA, Corella D, et al. Effects of a Mediterranean-style diet on cardiovascular risk factors: a randomized trial. Ann Intern Med 2006;145:1-11._3. Esposito K, Marfella R, Ciotola M, et al. Effect of a Mediterranean-style diet on endothelial dysfunction and markers of vascular inflammation in the metabolic syndrome: a randomized trial. J Am Med Assoc 2004;292:1440-6._4. de Lorgeril M, Salen P. Modified Cretan Mediterranean diet in the prevention of coronary heart disease and cancer. In: Simopoulos AP, Visioli F, eds. Mediterranean Diets. World Review Nutr Diet. Basel: Karger, 2000:1-23._5. Simopoulos AP. The traditional diet of Greece and cancer. Eur J Cancer Prev 2004;13:219-30.
Mediterranean diet wards off childhood respiratory allergies
Protective effect of fruits, vegetables and the Mediterranean diet on asthma and allergies among children in Crete.
"Mediterranean" diet rich in fruits, vegetables and nuts protects against allergic rhinitis and asthma symptoms, suggests research published ahead of print in Thorax.
The researchers assessed the dietary habits, respiratory symptoms, and allergic reactions of almost 700 children living in four rural areas on the Greek island of Crete.
The children were all aged between 7 and 18 years of age.
Skin allergies are relatively common in Crete, but respiratory allergies, such as asthma and allergic rhinitis are relatively rare.
Parents completed detailed questionnaires on their children's allergic and respiratory symptoms and dietary habits.
Whether the children ate a "Mediterranean" diet was measured against a set of 12 foodstuffs, including fruits, vegetables, whole-grains, legumes, nuts, and olive oil.
Eight out of 10 children ate fresh fruit, and over two thirds of them ate fresh vegetables, at least twice a day.
The effect of diet was strongest on allergic rhinitis, but it also afforded protection against asthma symptoms and skin allergy.
Children who ate nuts at least three times a week were less likely to wheeze.
Nuts are a rich source of vitamin E, the body's primary defence against cellular damage caused by free radicals. And they contain high levels of magnesium, which other research suggests, may protect against asthma and boost lung power.
And a daily diet of oranges, apples, and tomatoes also protected against wheezing and allergic rhinitis.
Grapes in particular seemed to protect against current and previous wheezing and allergic rhinitis, even after adjusting for other potentially influential factors.
Red grape skin contains high levels of antioxidants as well as resveratrol, a potent polyphenol, known to curb inflammatory activity, say the authors.
But high consumption of margarine doubled the chances of asthma and allergic rhinitis, the findings showed.
Adherence to the Mediterranean food pattern helps
Adherence to the Mediterranean food pattern predicts the prevalence of hypertension, hypercholesterolemia, diabetes and obesity, among healthy adults.
A diet score (range 0–55) has been developed that assesses adherence to the Mediterranean diet. For the consumption of items presumed to be close to Mediterranean dietary pattern (non-refined cereals, fruits, vegetables, legumes, olive oil, fish and potatoes) scores 0 to 5 for never, rare, frequent, very frequent, weekly and daily consumption were assigned, while for the consumption of foods presumed to be away from this pattern (red meat and products, poultry and full fat dairy products) scores on a reverse scale were assigned.
The Mediterranean diet was a strong predictor of non-occurence of these diseases.
Mediterranean Diet Halves Risk of Lung Disease
A Mediterranean diet halves the chances of developing progressive inflammatory lung disease (COPD), reveals a large study, published ahead of print in Thorax.
COPD (chronic obstructive pulmonary disease) is an umbrella term for chronic progressive lung disease, such as emphysema and bronchitis. It is expected to become the third leading cause of death worldwide by 2020, with cigarette smoking the primary factor in its development.
The researchers tracked the health of almost 43,000 men, who were already part of the US Health Professionals Follow up Study. This began in 1986 and involved more than 50,000 US health care professionals aged between 40 and 75, who were surveyed every two years.
They were asked questions about lifestyle, including smoking and exercise, diet and medical history. Dietary intake was assessed in detail every four years.
Eating patterns fell into two distinct categories: those who ate a diet rich in fruit, vegetables, whole grains and fish (Mediterranean diet); and those who ate a diet rich in processed foods, refined sugars, and cured and red meats (Western diet).
Between 1986 and 1998, 111 cases of COPD were newly diagnosed.
The Mediterranean diet was associated with a 50% lower risk of developing COPD than the Western diet, even after adjusting for age, smoking, and other risk factors.
And men who ate a predominantly Western diet were more than four times as likely to develop COPD, even after taking account of other influential factors.
The higher the compliance with a Mediterranean diet, the lower was the risk of developing COPD over the 12 year period.
Conversely, the higher the compliance with the Western diet, the higher was the risk of developing COPD.
Mediterranean diet and physical activity each associated with lower death rate over 5 years
Eating a Mediterranean diet and following national recommendations for physical activity are each associated with a reduced risk of death over a five-year period, according to two reports in the December 10/24 issue of Archives of Internal Medicine, one of the JAMA/Archives journals. Both studies use data from the National Institutes of Health-AARP Diet and Health Study, which began when questionnaires were returned from 566,407 AARP members age 50 to 71 in six states between 1995 and 1996.
In one study, Panagiota N. Mitrou, Ph.D., then of the National Cancer Institute, Bethesda, Md., and now of the University of Cambridge, England, and colleagues used a nine-point scale to assess conformity with the Mediterranean diet in 380,296 of the participants (214,284 men and 166,012 women) with no history of chronic disease. Components of the diet included vegetables, legumes, fruits, nuts, whole grains, fish, ratio of monounsaturated fats, alcohol and meat. During five years of follow-up, 12,105 participants died, including 5,985 from cancer and 3,451 from cardiovascular disease. Those with higher Mediterranean diet scores were less likely to die of any cause or of cancer or heart disease.
Fruit and vegetable intake and head and neck cancer
Fruit and vegetable intake and head and neck cancer in a large United States prospective cohort study: Abstract 849
A new study among AARP members shows that just one additional serving of fruit and vegetables per day may lower your risk of head and neck cancer, but the data suggest that you may not want to stop at just one, according to researchers from the National Cancer Institute.
A large prospective study of 500,000 men and women aged 50 and older has found that those who ate more fruit and vegetables had a reduced risk of head and neck cancer. Head and neck cancer is the sixth leading cause of cancer-related mortality worldwide, resulting in more than 350,000 deaths annually.
"Identifying protective factors for head and neck cancer is particularly important as it has a high mortality rate," said Neal Freedman, Ph.D., cancer prevention fellow at the National Cancer Institute.
At the beginning of the study, participants reported their typical dietary habits on a food frequency questionnaire. Freedman and his colleagues followed participants for five years and recorded all diagnoses of head and neck cancer cases during this time.
In their findings, the researchers report that participants who ate six servings of fruit and vegetables per day per 1000 calories had 29 percent less risk for head and neck cancer than did participants who consumed one and a half servings per 1000 calories per day. Typically, adults consume approximately 2000 calories per day. One serving equals approximately one medium sized fresh fruit, one half cup of cut fruit, six ounces fruit juice, one cup leafy vegetables, or one half cup of other vegetables.
"Increasing consumption by just one serving of fruit or vegetables per 1000 calories per day was associated with a six percent reduction in head and neck cancer risk," Freedman said.
According to Freedman, people who ate a lot of fruit also tended to eat a lot of vegetables, and vice versa. To measure these two types of foods independently, the researchers included both fruit and vegetable intake in the statistical models, a common statistical approach. This allowed them to compare participants with different levels of fruit consumption while holding constant the level of vegetable intake and vice versa. When examining fruit and vegetable intake simultaneously, the protective association with vegetables seemed to be stronger than the association with fruits.
"Although we cannot absolutely rule out a cancer preventive role for other lifestyle factors that go along with eating more fruits and vegetables, our results are consistent with those from previous studies," Freedman said. "Our study suggests that fruit and vegetable consumption may protect against head and neck cancer and adds support to current dietary recommendations to increase fruit and vegetable consumption."
Flavonols and pancreatic cancer risk
A study of food consumption in 183,518 residents of California and Hawaii has found that a diet high in flavonols might help reduce pancreatic cancer risk, especially in smokers. These compounds are generally ubiquitous in plant-based foods, but are found in highest concentrations in onions, apples, berries, kale and broccoli.
People who ate the largest amounts of flavonols had a 23 percent reduced risk of developing pancreatic cancer compared to those who ate the least, according to a research team led by Laurence Kolonel, M.D., Ph.D., at the Cancer Research Center of Hawaii.
Smokers gained the most benefit. Those who ate the most flavonols reduced their risk of developing pancreatic cancer by 59 percent, compared to those who ate the least, says the study’s lead author, Ute Nöthlings, DrPH, who conducted the study as a postdoctoral fellow in Hawaii and is now a researcher at the German Institute of Human Nutrition Potsdam-Rehbruecke.
‘The effect was largest in smokers, presumably because they are at increased pancreatic cancer risk already," said Nöthlings. Smoking is the only established risk factor for pancreatic cancer, and "short of stopping tobacco use, it has been difficult to consistently show lifestyle factors that might help protect against this deadly cancer," she says.
As part of a larger research project known as The Multiethnic Cohort Study, Kolonel and Nöthlings followed the participants for an average of eight years after they filled out a comprehensive food questionnaire.
Although Nöthlings says the study has a large statistical power because of the large number of pancreatic cancer cases (529) that occurred in the study population, she says that this one study cannot firmly answer the question of whether flavonols can prevent development of pancreatic cancer. "Further epidemiological studies in other populations and geographic regions are needed to confirm our findings," she said.
The study also is the first to examine prospectively specific classes of flavonols and pancreatic cancer risk.
The researchers looked at consumption of three flavonols: quercetin, which is most abundant in onions and apples; kaempferol, found in spinach and some cabbages; and myricetin, found mostly in red onions and berries.
Of the three individual flavonols, kaempferol was associated with the largest risk reduction (22 percent) across all participants. When the researchers divided intake into quartiles, and then compared highest intake to lowest, all the three classes of flavonols were associated with a significant trend toward reduced pancreatic cancer risk in current smokers, but not in never or former smokers. The interaction with smoking status was statistically significant for total flavonols, quercetin and kaempferol.
The researchers say their study did not examine the biological mechanisms by which these flavonols could exert a protective effect against pancreatic cancer. "But anti-carcinogenic effects of flavonoids in general have been attributed to the ability of these constituents to inhibit cell cycle, cell proliferation and oxidative stress, and to induce detoxification enzymes and apoptosis," Nöthlings said.
Studies Force New View on Biology, Nutritional Action of Flavonoids
Flavonoids, a group of compounds found in fruits and vegetables that had been thought to be nutritionally important for their antioxidant activity, actually have little or no value in that role, according to an analysis by scientists in the Linus Pauling Institute at Oregon State University.
However, these same compounds may indeed benefit human health, but for reasons that are quite different – the body sees them as foreign compounds, researchers say, and through different mechanisms, they could play a role in preventing cancer or heart disease.
Based on this new view of how flavonoids work, a relatively modest intake of them – the amount you might find in a healthy diet with five to nine servings of fruits and vegetables – is sufficient. Large doses taken via dietary supplements might do no additional good; an apple a day may still be the best bet.
A research survey, and updated analysis of how flavonoids work and function in the human body, were recently published in Free Radical Biology and Medicine, a professional journal.
“What we now know is that flavonoids are highly metabolized, which alters their chemical structure and diminishes their ability to function as an antioxidant,” said Balz Frei, professor and director of the Linus Pauling Institute. “The body sees them as foreign compounds and modifies them for rapid excretion in the urine and bile.”
Flavonoids are polyphenolic compounds with some common characteristics that are widely found in fruits and vegetables and often give them their color – they make lemons yellow and certain apples red. They are also found in some other foods, such as coffee, tea, wine, beer and chocolate, and studies in recent years had indicated that they had strong antioxidant activity – and because of that, they might be important to biological function and health.
“If you measure the activity of flavonoids in a test tube, they are indeed strong antioxidants,” Frei said. “Based on laboratory tests of their ability to scavenge free radicals, it appears they have 3-5 times more antioxidant capacity than vitamins C or E. But with flavonoids in particular, what goes on in a test tube is not what’s happening in the human body.”
Research has now proven that flavonoids are poorly absorbed by the body, usually less than five percent, and most of what does get absorbed into the blood stream is rapidly metabolized in the intestines and liver and excreted from the body. By contrast, vitamin C is absorbed 100 percent by the body up to a certain level. And vitamin C accumulates in cells where it is 1,000 to 3,000 times more active as an antioxidant than flavonoids.
The large increase in total antioxidant capacity of blood observed after the consumption of flavonoid-rich foods is not caused by the flavonoids themselves, Frei said, but most likely is the result of increased uric acid levels.
But just because flavonoids have been found to be ineffectual as antioxidants in the human body does not mean they are without value, Frei said. They appear to strongly influence cell signaling pathways and gene expression, with relevance to both cancer and heart disease.
“We can now follow the activity of flavonoids in the body, and one thing that is clear is that the body sees them as foreign compounds and is trying to get rid of them,” Frei said. “But this process of gearing up to get rid of unwanted compounds is inducing so-called Phase II enzymes that also help eliminate mutagens and carcinogens, and therefore may be of value in cancer prevention.
“Flavonoids could also induce mechanisms that help kill cancer cells and inhibit tumor invasion,” Frei added.
It also appears that flavonoids increase the activation of existing nitric oxide synthase, which has the effect of keeping blood vessels healthy and relaxed, preventing inflammation, and lowering blood pressure – all key goals in prevention of heart disease.
Both of these protective mechanisms could be long-lasting compared to antioxidants, which are more readily used up during their free radical scavenging activity and require constant replenishment through diet, scientists say.
However, Frei said, it’s also true that such mechanisms require only relatively small amounts of flavonoids to trigger them – conceptually, it’s a little like a vaccine in which only a very small amount of an offending substance is required to trigger a much larger metabolic response. Because of this, there would be no benefit – and possibly some risk – to taking dietary supplements that might inject large amounts of substances the body essentially sees as undesirable foreign compounds.
Numerous studies in the United States and Europe have documented a relationship between adequate dietary intake of flavonoid-rich foods, mostly fruits and vegetables, and protection against heart disease, cancer and neurodegenerative disease, Frei said.
FRESH VEGETABLES, FRUITS REDUCE DIABETES RISK
Eating just one more serving of green leafy vegetables or three more servings of fruit a day reduces the risk of developing Type II diabetes, according to results of data analysis performed by researchers in the Tulane School of Public Health and Tropical Medicine and the Harvard School of Public Health. The research team also found that one serving of fruit juice a day increased the risk of Type II diabetes in women.
Tulane epidemiologist Dr. Lydia Bazzano says, “Based on the results of our study, people who have risk factors for diabetes may find it helpful to fill up on leafy greens like lettuces, kale and spinach and whole fruits, like apples, bananas, oranges and watermelon rather than drink fruit juices, which deliver a big sugar load in a liquid form that gets absorbed rapidly.”
Bazzano, an assistant professor of epidemiology, cautioned that since this is one of the first studies to separate fruit juice consumption from fruits as a whole, the association between juice and diabetes must be confirmed by additional research.
She and her team analyzed 18 years worth of diet and health data from 71,346 nurses who participated in the Nurses’ Health Study from 1984 to 2002. The women were all between 38 and 63 years old and diabetes-free when the study began. Approximately 7 percent of the participants developed diabetes over the course of the study.
The researchers determined that the association between fruit and green leafy vegetable consumption and lowered diabetes risk remained after other factors, such as family history, cigarette smoking and weight, were analyzed. However, they found that women who ate more fruits and green leafy vegetables also were likely to be older, non-smokers and more physically active.
In addition to emphasizing the importance of eating whole fruits and green leafy vegetables to prevent diabetes, the team also recommends replacing refined grains and white potatoes with whole fruit or green leafy vegetable servings. White flours and potatoes have been associated with an increased risk of diabetes.
