The Mediterranean diet: Does it really prevent heart disease?

If you pay attention to diet advice,  you’ve probably noticed the recommendation that we should follow a “Mediterranean” diet. The trend began when a well-known study conducted in the 1960s found that people who lived near the Mediterranean Sea were less likely to die from heart disease, most likely due to their diets. But does that evidence hold true today?

Let’s start off with defining exactly what is a Mediterranean diet. Researchers at the Cochrane Collaboration, who recently conducted a systematic review of studies on the Mediterranean diet, used the following criteria:

• a high ratio of monounsaturated fats to saturated fats
• low to moderate consumption of red wine consumption
• high consumption of legumes such as beans, peas, nuts and lentils
• high consumption of grains and cereals
• high consumption of fruits and vegetables
• low consumption of meat and meat products and increased consumption of fish
• moderate consumption of milk and dairy products

Each study included in the review tested a diet that followed two or more of these principles.

Their review, published last month, included 11 randomized, controlled trials that measured the impact of a Mediterranean diet compared to minimal or no intervention. Five were conducted with healthy individuals and six trials involved people who are at increased risk of cardiovascular disease or cancer.

The reviewers noted that the evidence available on this topic isn’t consistent. Because the studies were so different, it was not possible to combine data which made it tough to draw sweeping conclusions. Researchers did find small reductions in total cholesterol levels as well as in the harmful LDL cholesterol levels.  Many of the trials also demonstrated a reduction in blood pressure among participants on a Mediterranean diet.

In the end, the researchers concluded that a Mediterranean diet does reduce some cardiovascular risk factors, but more evidence is needed to look at the effects of specific diet recommendations for different populations.