The Disease-Preventive Power of the Mediterranean DietJuly 2005
By Dale Kiefer
Earlier this year, news headlines extolled the health and anti-aging benefits of the Mediterranean diet, characterized by fish that provide omega-3 fatty acids, relatively copious amounts of olive oil, and antioxidant-rich fruits, vegetables, and herbs.
Epidemiological evidence has long suggested that the Mediterranean diet offers life-extending benefits. Recent studies associate this diet with lowered cardiovascular risk and increased life span.1 This is especially true among Greeks and Spaniards, who adhere most closely to the “classic” Mediterranean diet that is believed to specifically reduce cancer risk and protect cardiovascular health.2-8
The traditional Mediterranean diet is closely associated with the olive-growing regions of the Mediterranean Sea. Monounsaturated fats from olive oil and omega-3 fatty acids from fish are the predominant fats in the Mediterranean diet. Saturated fat, which is far more common in the diets of North Americans, makes up a relatively small portion of the Mediterranean diet.
An EPIC Study
Earlier this spring, scientists involved in Europe’s massive EPIC-elderly study released key findings from nearly a decade of research. EPIC (European Prospective Investigation into Cancer and Nutrition) is the largest study to date to provide convincing evidence that diet directly affects life span.
More than 74,000 healthy seniors aged 60 years or older from nine European countries participated in this eight-year study of factors affecting the incidence of cancer and other chronic diseases. Biological, dietary, lifestyle, and environmental factors were examined in relation to overall health. Researchers assessed the impact on health and longevity of omega-3 essential fatty acids such as those found in fatty fish like salmon and mackerel, as well as of monounsaturated fats obtained almost exclusively from olive oil.
The researchers developed a 10-point scale to quantify degree of adherence to the modified diet, and then compared scores with mortality data. Subjects who adhered most closely to the classic Mediterranean diet while consuming the least saturated fat earned the highest scores. Higher scores were clearly associated with longer life span. As the scientists noted, “. . . adherence to a modified Mediterranean diet . . . was associated with a significantly longer life expectancy in apparently healthy elderly people . . .”9
In essence, the data from this enormously important study show that adherence to a Mediterranean-type diet can extend life. Individuals who improved their scores by just two points on the 10-point scale increased their life expectancy by 7%. As an example, a 60-year-old man who adhered to the diet could expect to live a year longer than another man of the same age who did not follow the diet. According to the researchers, “The reduction in mortality in relation to a dietary score was more striking than expected . . .”9
In a further study, the EPIC scientists found that the longevity-promoting effects of the Mediterranean diet were even more dramatic in adults with coronary heart disease. When individuals with prevalent coronary heart disease at the time of enrollment improved their adherence to the Mediterranean diet by two points on the 10-point scale, they experienced a 27% lower rate of mortality and a 31% lower rate of cardiac death.10
The great question associated with the anti-aging benefits ascribed to the Mediterranean diet is how, exactly, the diet is responsible for the impressive, observed effects on longevity. Five years earlier, researchers had estimated that up to 25% of the incidence of colorectal cancer, about 15% of the incidence of breast cancer, and roughly 10% of the incidence of prostate, pancreatic, and endometrial cancers could be prevented by replacing the typical Western diet—high in saturated fat and low in omega-3 fatty acids, phytonutrients, and antioxidants—with the Mediterranean diet.11
To gain a better understanding of how the Mediterranean diet prolongs life, we need to examine the diet’s fundamental components, which include fatty acid-rich fish, antioxidants, phytonutrients, and olive oil.
Dangers of Polyunsaturated Fats
An enormous amount of scientific data documents the health risks associated with excess consumption of polyunsaturated fatty acids. While the polyunsaturated fats known as omega-6 fatty acids are essential to optimal health, most Americans and citizens of other Western nations consume far too many omega-6 polyunsaturated fatty acids and not enough omega-3 polyunsaturated fatty acids. Although a roughly 2:1 ratio of omega-6 to omega-3 fatty acids is considered optimal, most Americans consume these fats in a lopsided ratio that approaches 10:1.12,13 For optimal health and longevity, it is critical to achieve a dietary balance of these important nutrients. Given that the vast majority of people in Western countries consume excessive amounts of omega-6 fatty acids, attention should be focused on consuming adequate amounts of omega-3 fatty acids.
Omega-3 polyunsaturated fatty acids have been shown to have anti-cancer, anti-inflammatory, and antihypertensive effects, and to reduce the risk of stroke, heart arrhythmias, dementia, and heart attack when consumed in balance with omega-6 fatty acids.14-21
Omega-3 fatty acids influence health and well-being through a variety of mechanisms. These include modulation of cell membranes’ physical and chemical properties, and regulation of the metabolism of immune system components that are involved in inflammation.
Evidence also suggests omega-3 polyunsaturated fatty acids regulate body functions through the modulation of specific genes.17,22
The omega-3 fatty acids EPA (eicosapentanoic acid) and DHA (docosahexaenoic acid) are found in abundance in fatty fish and some marine mammals, as well as in the algae (seaweed) upon which they feed. A third polyunsaturated fatty acid, alpha-linolenic acid, can be converted into DHA and EPA. While alpha-linolenic acid is available from sources such as canola oil, flaxseed oil, and walnuts, its conversion to DHA is slow and inefficient.23,24 Scientists believe that direct consumption of DHA and EPA is the best way to obtain adequate omega-3 polyunsaturated fatty acids.16,25-32
The importance of DHA and EPA cannot be overstated. For example, adequate intake of omega-3 fatty acids during early childhood is thought to play a role in preventing attention deficit hyperactivity disorder (ADHD) and in improving learning and academic performance.30 In older adults, consuming omega-3 fats such as DHA and EPA may reverse signs of brain aging and protect against development of Alzheimer’s disease and other causes of age-associated dementia and decline.18,27-29,33-36
Power of Olive Polyphenols
For millennia, olives have provided a staple source of high-energy food and critical nutrients for the many civilizations that have thrived in the Mediterranean area.
Researchers in Barcelona and other southern European cities lead the world in investigating the remarkable health benefits of olives.37-41 While the monounsaturated fats in olive oil are clearly a crucial component of the Mediterranean diet, a lesser known but no less important component is the rich mixture of antioxidant polyphenols in olives.5 Once discarded as a by-product of the olive oil-extraction process, olive polyphenols concentrated in the watery juice of the olive fruit have an impressive array of beneficial properties.37,41-62
For example, laboratory studies of cells grown in culture have shown that the primary olive oil polyphenol—hydroxytyrosol—scavenges the dangerous free radical hydrogen peroxide, which is a by-product of normal cellular respiration.42 As Life Extension members are well aware, the damage caused by free radicals includes DNA damage that can lead to premature aging, cancer, and other degenerative conditions.63-65
In addition to in-vitro experiments, tests with hydroxytyrosol-rich polyphenols in vivo have also yielded impressive results. For example, scientists in the Netherlands fed animals either polyphenol-rich extra-virgin olive oil or extra-virgin olive oil with the polyphenol components removed. Levels of the antioxidant vitamin E were significantly increased in the animals that received the polyphenols, indicating that olive oil polyphenols improved antioxidant defense systems.59 Removal of hydroxytyrosol-rich polyphenols from the diet also rendered LDL (low-density lipoprotein) more susceptible to oxidation. As Life Extension members are aware, LDL oxidation is thought to play an important role in the development of atherosclerosis and cardiovascular disease.