We know a Mediterranean diet is healthy and lengthens life. But, which items in this diet are most helpful? Well, finally, at study has teased out items in the Mediterranean diet that are most responsible.
More Information:The study was published in the BMJ. It was a population-based cohort study from Greece.
According to an excellent review of the study in Heartwire CME (quoted below), “the largest effects on reduced mortality came from drinking moderate amounts of alcohol, eating little meat, eating lots of vegetables, eating fruits and nuts, and using olive oil. However, the individual components of the Mediterranean diet had an additive protective effect.”
“Overall diet is more important than individual components, with emphasis on moderate–but not excessive–wine consumption, particularly during meals, preference for olive oil as the main added lipid, low consumption of meat, and high consumption of vegetables, fruits, and legumes,” author Dr Dimitrios Trichopoulos (Harvard School of Public Health, Boston, MA) told Heartwire.
The researchers examined data from healthy individuals in Greece who participated in the European Prospective Investigation into Cancer and Nutrition (EPIC) trial.
Although this study did not examine causes of death, previous studies in this cohort showed that the Mediterranean diet has the greatest effect on cardiac mortality, Trichopoulos said.
The study is published online June 24, 2009 in BMJ.
A Toast to Long Life
To investigate the relative importance of each of the components of the Mediterranean diet on longevity, the researchers looked at data from the Greek segment of EPIC, from over 23 000 healthy men and women aged 20 to 86 at enrollment.
The researchers calculated a Mediterranean diet score from a diet questionnaire filled in by the participants at study entry.
The diet score was based on nine components of the Mediterranean diet: vegetables, legumes, fruit and nuts, dairy products, cereals, meat and meat products, fish and seafood, monounsaturated-to-saturated lipid ratio, and ethanol consumption.
High consumption of a beneficial food, low consumption of a harmful food (meat or dairy products), and moderate consumption of alcohol were each assigned a value of 1; other levels of consumption were assigned a value of 0, for a score of 0 to 9.
The researchers compared longevity for individuals with scores above or below the median, where the median was about five servings of vegetables and three to four servings of fruits and nuts a day, said Trichopoulos. Moderate intake of alcohol was one to five small glasses of wine (10 g/day to less than 50 g/day) for men and half that for women.
As is typical in the Greek population, many individuals were overweight or obese and many men were smokers. Most were moderately active.
After a mean follow-up of 8.5 years, more deaths occurred in the participants with low vs high Mediterranean-diet scores.
The contribution of each of the diet components to lower mortality were: moderate consumption of alcohol (23.5% of the effect), low consumption of meat (16.6%), high consumption of vegetables (16.2%), high consumption of fruits and nuts (11.2%), high monounsaturated-to-saturated lipid ratio (10.6%), and high consumption of legumes (9.7%).
Eating lots of cereal products and few dairy products contributed to only 5% of the effect, and consumption of fish was associated with a nonsignificant increase in mortality.
Trichopoulos was not surprised that the study found that moderate consumption of alcohol — mostly wine drunk with meals — was such a prominent contributor to longevity. Wine consumed in the Greek diet is comparable to wine consumption that is part of the “French paradox,” he noted.
The researchers acknowledge that the long follow-up means that diets could have changed over the study. In addition, the effects of each food might be synergistic.
No Single Miracle Food
Commenting on the study for heartwire , Dr Teresa T Fung (Harvard School of Public Health, Boston, MA), who was not involved with the study, said that she was surprised that moderate consumption of alcohol — which is known to reduce risk of cardiac disease — had such a strong contribution to reduced risk of mortality.
Importantly, this work confirms that it is not one single component of the Mediterranean diet that is driving reduced risk of mortality, she added. “In order to promote longevity, people have to do several things at the same time. They just can’t focus on one food — just eat blueberries or take a folic-acid pill. It’s a whole lifestyle, whole diet approach for health promotion.”
However, the study does not indicate whether each of the components of the Mediterranean diet linked to decreased risk of mortality are also linked to reduced risk of incidence of the diseases that cause the mortality, Fung added.
The authors disclosed having no conflict of interest. The study was supported by the Europe Against Cancer Program of the European Commission, the Greek Ministries of Health and Education, and a grant to the Hellenic Health Foundation by the Stavros Niarchos Foundation.
Trichopoulou A, Bamia C, Trichopoulos D. Anatomy of health effects of Mediterranean diet: Greek EPIC prospective cohort study. BMJ; 2009: 338:b2337.