You've probably heard of the “Mediterranean diet”, whose power to reduce the risk of cardiovascular disease has been documented in numerous studies published over the past 25 years.
The preventive health benefits of rural Mediterranean peoples were revealed in the famous “Seven Countries” study, in which researchers examined the rates of degenerative disease—chiefly heart disease—in various regions of the world where traditional diets remained dominate.
Starting in the late 1950's, Ancel Keys, Ph.D. and his colleagues at the University of Minnesota set out to test a hypothesis. They thought that differences in lifestyle and diet among men in stable, rural populations with wide contrasts in habitual diet—especially the kinds of fats that predominated in various traditional diets—might yield significant differences in the frequency of heart attacks and stroke.
(The Seven Countries Study did not include women because of the relative rarity of cardiac events among American females at the time—a situation that has changed radically since—and the invasiveness of the field examinations, which would have posed problems in these traditional cultures.)
From 1958 to 1970 they conducted surveys among men ages 40-59, in eighteen areas of seven countries, where the Minnesota team continues to record deaths and their causes up to the present day.
The characteristics of the traditional Mediterranean diet, as revealed by the Seven Countries Study, reflect the way people in rural areas of Greece and southern Italy used to eat.
The daily fare consisted mostly of vegetables, fruit, bread, rice, or pasta, olive oil, and fish. This combination of foods, consumed in the traditional proportions, made their diets low in pro-inflammatory omega-6 and saturated fats—which are overabundant in the standard American diet—and high in the fibers and anti-inflammatory omega-3 fatty acids lacking in the standard American diet.
These farming and fishing folk ate almost as much fat as Americans do today, but most of it came from olive oil. Accordingly, instead of the saturated and omega-6 fats that predominate in the American diet, they consumed mostly monounsaturated fat, since it constitutes 80 percent of olive oil.
The omega-3 connection
These higher omega-3 intake levels among rural Greeks and Italians also had a greater health impact than they would have here, because their diets were also low in the omega-6 fats we eat far too much of.
This is because omega-6 fats compete with omega-3s for passage through the metabolic bottlenecks that lead to the incorporation of one or the other kind of fatty acid into cell walls and their ability to exert hormone-like influence on basic metabolic processes. When the two families of fatty acids are consumed in comparable amounts, the omega-3s can exert profound preventive effects with regard to heart disease and cancer. But when omega-6 fats predominate as overwhelmingly as they do in America, omega-3s get crowded out.
As the authors of a recent review article (de Lorgeril M 2006) put it, “In the context of a diet rich in [monounsaturated] oleic [fatty] acid, poor in saturated fats and low in omega-6 fatty acids… a dietary pattern characterising the traditional Mediterranean diet… even small doses of omega-3 fatty acids… might be very protective.”
The Mediterranean diet also contains much smaller amounts of refined flour foods (breads, pastries, and pasta) or meat than Americans eat. In addition, the pork, lamb, and goat found in the traditional Mediterranean diet were raised on grass and table scraps rather than grains, so their meats had healthier fat profiles—smaller proportions of omega-6 and saturated fatty acids, with higher proportions of plant-type omega-3 fatty acids—than are typical of conventional, factory-farmed American meats.
In short, the Mediterranean diet could be fairly characterized as the “vegetables, fruit, and fish” diet. Early analyses of the Mediterranean diet attributed much of its cardiovascular benefit to the heart-healthy monounsaturated fatty acids in olive oil (e.g., oleic acid).
But it now appears that the greater gift of using olive oil instead of “American” oils—like those from corn, canola, soy, safflower, and sunflower—stems from two sources other than monounsaturated fat itself, which has no strong effect, either positive or negative, on cardiovascular health:
- As we said, by favoring olive oil and avoiding processed foods, the Mediterranean diet ensures far lower intake of the pro-inflammatory omega-6 fatty acids that dominate American diets.
- The potent hydroxytyrosol antioxidants abundant in unrefined, “extra virgin” olive oil are very good for vascular health (see “Antioxidants in Extra Virgin Olive Oil Add Extra Cardiac Benefits” from our January 2, 2006 issue). Extra virgin olive oil is the kind that most rural Mediterranean peoples once made in their own hand presses, with olives from their own groves.
And groundbreaking epidemiological research—conducted, coincidentally in Greece—revealed that people who eat fish enjoy substantially lower levels of most blood markers for the inflammation now believed to promote and exacerbate cardiovascular disease (see “Fish Inhibits Heart-Attacking Inflammation” from our July 11, 2005 issue).
Mediterranean diet linked to lower Alzheimer's risk
The cost of Alzheimer's—which now affects more than 13 million people worldwide—is over $100 billion in the US alone. So it was encouraging to read the results of a study in 2258 elderly New Yorkers, which indicate that diets closely resembling the classic Mediterranean diet may cut the risk of developing Alzheimer's disease by about 40 percent, compared to the standard American diet.
Professor Clive Ballard, director of research for Britain's Alzheimer's Society, called it a significant contribution to the fast-growing body of evidence that links diet and the risk of Alzheimer's: “There have been a number of studies looking separately at the benefits of eating fruit, vegetables and oily fish for reducing your risk of Alzheimer's disease. This study supports the idea that eating a combined diet of plenty of fruit, vegetables and fish might help to prevent dementia.”
The researchers, from Columbia University Medical Center, gathered medical and neurological histories from the participants—all of whom were non-demented and home-dwelling—performed physical and neurological exams, and interviewed each face to face: a process that was repeated every 18 months.
As lead author Nikolaos Scarmeas wrote, “Higher adherence to the Mediterranean diet was associated with significantly lower risk of developing Alzheimer's disease.”
Scarmeas' team reported that each increasing point on the “Med diet score” was linked with a 10 percent drop in Alzheimer's risk.
Among the study participants whose diets most closely resembled the Mediterranean diet, the risk of Alzheimer's was 40 percent lower than the risk run by those whose regular diets bore the least resemblance to the Mediterranean model. The association was still significant after the researchers adjusted the results to account for confounding factors such as age, gender, ethnicity, body mass index, and smoking.
The risk reduction seen in this study is likely attributable to a combination of factors. Fruits and vegetables can help to lower blood pressure and prevent cardiovascular disease, both of which would reduce the risk of circulation-related dementia, and the antioxidants in produce help protect brain cells against damaging free radicals.”
Mediterranean diet may protect against vein problems
In another study from the region that gave us this healthful diet, Italian researchers found that risk of chronic obstructions in blood vessels in the elderly—called peripheral vascular disease (PVD)—is reduced in people who eat a Mediterranean-style diet (Antonelli-Incalzi R 2005).
PVD is typically caused by hardening of the arteries (atherosclerosis) and inflammation, and it is estimated to affect more than one in five people over the age of 56, with about 10 million Americans suffering the affliction.
The researchers assessed the food intake of 1,251 home-dwelling elderly people—average age of 68—using a diet questionnaire.
The study, called “InCHIANTI” and conducted by researchers at Rome's Universita Campus Biomedico, gauged the prevalence of PVD by measuring participants' blood pressure at the ankle and in the arm while at rest and again after five minutes on a treadmill, to produce the reliably PVD-predictive ankle-brachial index.
The researchers found that three dietary factors were associated with lower risks of PVD:
- A daily intake of vegetable fats—mostly monounsaturated, from olive oil—totaling 34 grams or more cut the risk of PVD by more than 60 percent.
- Higher blood levels of HDL cholesterol were also linked with a lower risk, with every 10 milligrams per decilitre increase associated with a 24 per cent lower risk.
Vitamin E intake of 7.7 milligrams per day or more cut the risk of PVD by 63 percent.
As co-investigator Raffaele Antonelli-Incalzi wrote, “Our findings suggest that a person with a high intake of vegetable lipids, mainly of olive oil and vitamin E are less likely to be affected by PVD.”
- Scarmeas N, Stern Y, Tang MX, Mayeux R, Luchsinger JA. Mediterranean diet and risk for Alzheimer's disease. Ann Neurol. 2006 Apr 18;59(6):912-921 [Epub ahead of print]
- Antonelli-Incalzi R, Pedone C, McDermott MM, Bandinelli S, Miniati B, Lova RM, Lauretani F, Ferrucci L. Association between nutrient intake and peripheral artery disease: results from the InCHIANTI study. Atherosclerosis. 2006 May;186(1):200-6. Epub 2005 Aug 19.
- Keys A, Aravanis C, Blackburn HW, Van Buchem FSP, Buzina R, Djordjevic BS, Dontas AS, Fidanza F, Karvonen MJ, Kimura N, Lekos D, Monti M, Puddu V, Taylor HL. Antonelli-Incalzi R, Pedone C, McDermott MM, Bandinelli S, Miniati B, Lova RM, Lauretani F, Ferrucci L. Association between nutrient intake and peripheral artery disease: results from the InCHIANTI study. Atherosclerosis. 2006 May;186(1):200-6. Epub 2005 Aug 19.
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- Kromhout D, Menotti A, Blackburn H (eds.) The Seven Countries Study: A Scientific Adventure in Cardiovascular Disease Epidemiology. 1994. Brouwer. Utrecht.
- Toshima H, Koga Y, Blackburn H. (eds.) Lessons for Science from the Seven Countries Study. 1995. Springer Verlag, Tokyo
- de Lorgeril M, Salen P. The Mediterranean-style diet for the prevention of cardiovascular diseases. Public Health Nutr. 2006 Feb;9(1A):118-23. Review.