The diet is often cited as beneficial for being low in saturated fat and high in monounsaturated fat and dietary fiber.[citation needed]
One of the main explanations is thought to be the health effects of olive oil included in the Mediterranean diet.
The Mediterranean diet is high in salt content. Foods such as olives, salt-cured cheeses, anchovies, capers, salted fish roe, and salads dressed with olive oil all contain high levels of salt. Salt is particularly important for salads dressed with virgin olive oil, because the antioxidants it contains are slightly bitter.
A study published in Archives of General Psychiatry shows that people who followed the Mediterranean diet, an eating regimen that is rich in fruits, vegetables, whole grains, fish, and nuts, were less likely to develop depression.
In addition, the consumption of red wine is considered a possible factor, as it contains flavonoids with powerful antioxidant properties.
Mireille Guiliano, author of the #1 bestseller French Women Don't Get Fat, credits the health effects of the Mediterranean diet to factors such as small portions, daily exercise, and the emphasis on freshness, balance, and pleasure in food.
Dietary factors may be only part of the reason for the health benefits enjoyed by these cultures. Genetics, lifestyle (notably heavy physical labor), and environment may also be involved.
In industrialized countries, about 75% of deaths in persons older than the age of 65 are now from cardiovascular diseases and cancer. However, a 10 year study published in the Journal of American Medicine found that adherence to a Mediterranean diet and healthful lifestyle was associated with more than a 50% lowering of early death rates.
The putative benefits of the Mediterranean diet for cardiovascular health are primarily correlative in nature; while they reflect a very real disparity in the geographic incidence of heart disease, identifying the causal determinant of this disparity has proven difficult. The most popular dietary candidate, olive oil, has been undermined by a body of experimental evidence that diets enriched in monounsaturated fats such as olive oil are not atheroprotective when compared to diets enriched in either polyunsaturated or even saturated fats. A recently emerging alternative hypothesis to the Mediterranean diet is that differential exposure to solar ultraviolet radiation accounts for the disparity in cardiovascular health between residents of Mediterranean and more northerly countries. The proposed mechanism is solar UVB-induced synthesis of Vitamin D in the oils of the skin, which has been observed to reduce the incidence of coronary heart disease, and which rapidly diminishes with increasing latitude.