Good news to share: Mediterranean diet gets kudos for heart health
Omega-3 fatty acids are a key part of cardioprotection
Attention: Eating fatty foods is no longer the bugaboo that we once thought. In fact, instead of warning your heart patients about the dangers of fat consumption, you might want to consider the growing body of evidence that eating the right kid of fat can protect their cardiovascular systems.
It’s not fat per se that’s the problem, but the kinds of fats we Americans like to chow down on and the other foods we turn to when we cut back on appetite-satisfying fat. Although heart disease has declined over the past two decades since Americans began to shun artery-clogging saturated fats and cholesterol, waistlines have expanded significantly and obesity has risen by 50% in the same time frame.
In an odd turn of events, some experts now say that the very tactic viewed as the key to weight control — stripping the diet of fat — seems to have backfired. Food manufacturers responded to fat fanaticism with a wave of fat-free, low-fat, and reduced-fat products, especially in desserts and snack foods that Americans crave.
Feeling deprived of the satisfying taste of fat, dieters justify eating as many fat-free products as they want, disregarding the fact that they are not calorie-free. Many low-fat and fat-free products have nearly as many calories as their full-fat versions.
Now nutritionists are singing high praises for the health benefits of the more balanced and satisfying Mediterranean diet, which centers around fish, olive oil, fruit, and vegetables, as one of the best possible prescriptions for a longer life.
Though relatively high in fat, the Mediterranean diet is considered healthy because it is rich in potentially protective nutrients: omega-3 fatty acids (also known as polyunsaturated fatty acids or essential fatty acids) found in fish, antioxidants such as vitamin E from fruits and vegetables, and monounsaturated fatty acids from olive oil.
Now researchers are finding that diets high in omega-3 fatty acids can prevent heart disease and even prevent second heart attacks in people who already have suffered a myocardial infarction.
Italian researchers reported on the results of a large clinical trial at the November scientific sessions of the American Heart Association in New Orleans.
"Despite the fact that good dietary habits are known to be the cornerstone of heart health, there are limited data demonstrating the amount of benefit for individuals who have had a heart attack," says Roberto Marchioli, MD. Marchioli is the coordinator of the GISSI-Prevenzione Study at the department of clinical pharmacology and epidemiology of Consorzio Mario Negri Sud in Santa Maria Imbaro, Italy.1
"A significantly lower risk of death was associated with eating more Mediterranean-style foods and fewer foods containing saturated facts, such as butter," says Marchioli. "People in the study who had the most butter and vegetable oils in their diet had a risk of death almost triple that of people who ate more fresh fruits and vegetables and used olive oil."
In general, the coronary heart disease death rates are much lower in Spain, Greece, and Italy, countries where the Mediterranean diet is considered the norm.
The GISSI-Prevenzione study, a clinical trial organized by the Italian National Association of Hospital Cardiologists and the Mario Negri Institute, evaluated long-term changes in the dietary habits of 11,324 Italians after a first heart attack. The study also assessed the effectiveness of prescribing extra amounts of omega-3 fatty acids and vitamin E.
Study participants had experienced heart attacks within the three months before the study began, and received routine examinations from their cardiologists for 3½ years. Their intake of certain foods was tracked with a questionnaire given just after their heart attack and again 12, 18, and 42 months later.
The dietary benefits extended to obese individuals with a body mass index (BMI) of 30 or greater. "Though the [BMI] of overweight people did not change significantly during follow-up, their dietary habits improved after their heart attacks," says Marchioli. "Their intake of healthy foods was relatively high at baseline and further improved during follow-up."
Researchers found that improving lifestyle across the board — eliminating stress, getting more exercise, stopping smoking, and eating a healthy diet — plus compliance with prescribed drug treatment are the keys to preventing the recurrence of cardiovascular disease.
It is important not only to create good dietary habits, says Marchioli, but to maintain them over time. "Eat foods such as fruit, vegetables, fish, and olive oil, which are rich in protective nutrients and eat few potentially harmful foods such as butter, red meat, and foods rich in animal fat. You can still enjoy your life and your food without being on a strict diet. This approach could increase the feasibility of adopting healthy dietary habits that will be maintained in the long term."
Results speak for themselves
Several studies in recent years have found a correlation between omega-3 fatty acids and lower risk of heart disease. Among those findings:
• Diets enriched with omega-3 fatty acids had significantly decreased blood pressure.2
• A review of 11 studies on omega-3 fatty acids concludes that 40 g to 60 g of fish per day significantly lowers the risk of death from all types of heart disease.3
• Studies in the Netherlands and the United States have indicated that eating just two fish meals, or 7 ounces of fish, a week can reduce a man’s risk of heart attack by 50%.4
• Alpha-linolenic acid, found prominently in canola oil, flaxseeds, soybean oil, walnuts, and many dark green leafy vegetables, also appears to offer strong protection against sudden cardiac death, according to a study from the Harvard School of Public Health.5
• Among 76,000 participants in the Nurses’ Health Study, those with the highest intake of alpha-linolenic acid had up to a 50% lower risk of fatal heart attacks when compared with women who consumed the least amount of this fat.6
• Also from the Nurses’ Health Study of 80,000 women initially ages 34 to 59: Total fat consumption did not affect coronary risk, but the kinds of fats the women ate did. Each 5% increase in calories from saturated fats (primarily from meats and dairy products) raised their risk of coronary disease by 17%.7
The mechanisms for omega-3’s cardioprotective action aren’t entirely clear, but there is evidence that alpha-linolenic acid in the form of flaxseed oil improves the elasticity of arteries, thereby improving circulation and decreasing cardiovascular risk.
Fish oils inhibit inflammation in blood vessel walls, prevent clotting, cause blood vessels to dilate, and promote regular cardiac rhythm.
Those actions are due to the role of omega-3s, a dietary component that most Americans are lacking in sufficient amounts, (and omega-6s, of which most of us get sufficient amounts in our diets) in creating prostaglandins, which affect blood vessel dilation or constriction and clot formation.
In addition, like aspirin, fish oils also limit thromboxane A2 production, which promotes blood stickiness and vasoconstriction. Therefore, these fatty acids help maintain regular blood flow and limit unwanted platelet aggregation that can contribute to plaque buildup.
Under the umbrella of the omega-3 fatty acids are EPA (eicosapentaenoic acid, from which the body manufactures prostaglandin) and DHA (docosahexaenoic acid), long-chain fatty acids found in cold water fish such as salmon, tuna, and herring. Flaxseed also is an excellent source of short-chain omega-3 fatty acid, says Udo Erasmus, PhD, a nutrition expert based in Vancouver, British Columbia, Canada, and author of Fats That Heal, Fats That Kill.8
Fats can have healing effect
The fats that heal really involve three substances, says Erasmus. "One is called omega-3 essential fatty acid, or alpha-linolenic acid. The second is omega-6, or linoleic acid. If you take these in the right ratio — about 1:2 — which is important, and you get enough of the both, the body makes several derivatives that are important for health. And some of these derivatives are turned into hormones called prostaglandins that are vital to optimal body functioning," he says.
In addition to lowering many cardiovascular risk factors, Erasmus says the healing fats have a broad range of positive effects. Effects include:
• optimize energy level and performance;
• improve brain function, mood, behavior, and intelligence;
• make skin soft, smooth, and velvety;
• improve digestive, gland, and organ functions;
• are anti-inflammatory, and dampen the overresponse of the immune system in autoimmune conditions;
• help transport minerals and keep bones strong;
• protect genes from being damaged;
• are required for hemoglobin production, cell growth, and cell division;
• have anticancer properties;
• help in fat loss and weight normalization.
Most research has been conducted on fish oil, but flaxseed oil, the vegetable alternative, has twice the concentration of omega-3s and a lower price tag.
"You can get what you need from vegetable sources, but you’d have to eat 123 pounds of broccoli a day. That’s not really practical," says Erasmus. He prefers a blend of oils for maximum health benefit including flaxseed, sesame and sunflower seeds, and rice germ, oat germ, lecithin, evening primrose oil, and rosemary oil as free radical scavengers.
That blend, sold in health food stores under the brand name Perfect Oil Blend, contains a near perfect balance of omega-3, alpha-linolenic acid, and omega-6 fatty acids, including alpha-linoleic and gamma-linolenic acids and contains antioxidants.
There also has been a preliminary study that links diets rich in essential fatty acids to a reduced risk of breast cancer and another that correlates high intake of extra virgin olive oil to preservation of cognitive function in healthy older people.9,10
References
1. Marchioli R, Valagussa F. The results of the GISSI-prevenzione trial in the general framework of secondary prevention. Eur Heart J 2000; 21:949-952.
2. Kimura S. Antihypertensive effect of docosahexaenoic acid in stroke-prone spontaneously hypertensive rats (in Japanese). Yakugaku Zasshi 2000; 120:607-619.
3. O’Keefe J, Harris W. From Inuit to implementation: omega-3 fatty acids come of age. Mayo Clin Proc 2000; 75:607-614.
4. Oomen C, Feskens E, Rasanen L, et al. Fish consumption and coronary heart disease mortality in Finland, Italy, and The Netherlands. Am J Epidemiol 2000; 151:999-1,006.
5. Ascherio A, Rimm E, Giovannucci E, et al. Dietary fat and risk of coronary heart disease in men: Cohort follow-up study in the United States. BMJ 1996; 313:84-90.
6. Hu F, Stampfer M, Manson J. Dietary intake of alpha-linolenic acid and risk of fatal ischemic heart disease among women. Am J Clin Nutr 1999; 69:890-897.
7. Hu F, Stampfer M, Manson J. Dietary saturated fats and their food sources in relation to the risk of coronary heart disease in women. Am J Clin Nutr 1999; 70:1,001-1,008.
8. Erasmus U. Fats That Heal, Fats That Kill. Burnby, BC, Canada: Alive Books; 1993.
9. Wang M, Liu YE, Ni J. Induction of mammary differentiation by mammary-derived growth inhibitor-related gene that interacts with an omega-3 fatty acid on growth inhibition of breast cancer cells. Cancer Res 2000; 60:6,482-6,487.
10. Youdim KA, Martin A, Joseph JA. Essential fatty acids and the brain: possible health implications. Int J Dev Neurosci 2000; 18:383-399.
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