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Epidemiology Studies of Mediterranean Diet

In his famous Seven Countries Studies in 1958-1964, an American Scientist Ancel Keys observed a lower percentage of people having a Coronary Heart Disease(CHD) in the Southern Italy (Overview:The Seven Countries Study in Brief, 2013). Hence, the term Mediterranean Diet was coined to refer to the characteristic of foods eaten by the people of the Mediterranean region in the 1950’s.

The diet started to gain popularity in 1990s when Dr.Walter Willett of Harvard University’s School of Public Health introduced the “Mediterranean diet pyramid” as a “cultural model for healthy eating” (Willett et al, 1995).

Numerous epidemiology studies have since linked Mediterranean Diet to a number of health benefits, including a lower risk of Alzheimer’s disease (Scarmeas et al, 2010), a lower risk of age-related changes in blood pressure (Núñez-Córdoba et al, 2009), promoting longevity (Trichopoulou et al, 2003 & Dye, 2012) and a promising result on its association with an improved cognitive function (Samieri et al, 2013), contradicting the lack of association of its beneficial effect on cognitive aging shown by Kesse-Guyot et al (2013). The diet’s preventive effect against cancer has produced mixed results, ranging from “favourably associated” with pancreatic cancer risk (Bosetti et al, 2013), “modest beneficial effect” on colorectal cancer risk (Bamia et al, 2013) to mixed results on association with breast cancer risk as presented by Cade et al (2011) and Couto et al (2013).

Due to variety in dietary practices of the countries bordering the Mediterranean region, a single definition of Mediterranean Diet is almost impossible. Trichopoulou (2004) identified eight key characteristics of a Mediterranean Diet as:

  • having high ratio of monounsaturated to saturated fat
  • moderate alcohol consumption
  • high consumption of legumes
  • high consumption of non-refined cereals
  • high consumption of fruits
  • high consumption of vegetables
  • low of consumption of meat
  • moderate consumption of milk and dairy products

As majority of the studies conducted have been “observational studies” of the “whole-diet approach”, it is unclear how individual component contributes to the overall cardiovascular health. A number of studies have tried to isolate the various components of the diet to identify those that produce the most benefits. Mozaffarian et al (2011) suggested that the lower level of saturated fat consumption in Mediterranean Diet contributes to the lower rate of CHD deaths, while an intervention study by Urpi-Sarda et al (2012) identified olive oil and nuts components in Mediterranean Diet as having anti-inflammatory effect on subjects with high cardiovascular risk.

In the latest large, clinical, randomized trial of high risk people, it has been shown that variations in Mediterranean Diet, specifically in the consumption of a higher proportion of olive oil and nuts can reduce the risk of heart attacks, strokes and cardiovascular deaths by more than 30% compared to those with less oil and nuts consumption (Estruch et al, 2013).

The prevalence of epidemiological studies associating Mediterranean Diet with many health benefits has identified it as one of the recommended diets to improve overall health, including diabetes management (Ajala et al, 2013) and cancer prevention (Giacosa et al, 2013).

This article was submitted as part of my Case Study.

 

REFERENCES

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