Posted on 03/13/2013 at 02:13:35 PM by Student BloggerBy Sarah Gold
The evidence supporting plant-heavy diets full of foods with unsaturated fats, omega-3 fatty acids, vitamins, minerals, and antioxidants (including a glass of red wine!) has grown over the last decade. Most health professionals agree that much of the benefit lies in the anti-inflammatory properties of these foods. The food and nutrition research in this area, however, has focused on specific foods or nutrients, rather than entire diet patterns. Could there be one diet that puts it all together? Turns out there is: a Mediterranean diet pattern, or one with plenty of fruits, vegetables, legumes, nuts, and olive oil, moderate amounts of fish and white meat, and small amounts of low fat dairy and red meat.
Many health professionals have touted the benefits of a Mediterranean lifestyle for years, but with support primarily from observational studies, which often leave room for significant confounding factors. Small clinical trials have provided evidence for the biological plausibility of such a diet (again, due to the anti-inflammatory properties of the diet's components), but data from a large scale clinical trial was missing. That is, until now. A new landmark study published in the latest issue of The New England Journal of Medicine tells us that the Mediterranean diet may be the way to go if you want to prevent cardiovascular disease (CVD).
The researchers recruited more than 7,500 Spanish men and women between the ages of 55-80 to participate in this randomized control trial. Participants had no incidence of CVD prior to joining the study, but were at high risk for developing it in that they either had type 2 diabetes, or at least three of the following risk factors: smoking, hypertension, dyslipidemia, overweight, obesity, or a family history of coronary heard disease (CHD). The participants were randomized into one of three groups: Mediterranean diet with emphasis on olive oil (4 tbsp recommended per day), Mediterranean diet with emphasis on nuts (1 ounce per day), or a control group (given advice to follow a low fat diet). No calorie provisions were provided. Participants were followed for an average of 4.8 years, and the primary outcome measured was incidence of a composite of CVD related outcomes (stroke, myocardial infarction, or death from CHD).
Both Mediterranean diet groups decreased their risk of CVD by 30%. When broken down to specific CVD end-points (stroke, myocardial infarction, and death from cardiovascular causes), the data showed nearly a 40% risk reduction in stroke; significant effects were not seen for the other outcome measures. What's even more interesting is that calories were not restricted, and significant weight loss was not seen in this study, indicating that diet improvements can affect a person's risk of CVD independent of weight. Some health professionals worry about recommending the addition of higher fat foods like olive oil and nuts to a diet, but it appears that in this study participants must have substituted these calories for other foods since significant weight gain was not seen either.
What's exciting about this study is the focus on the whole diet, not just one nutrient or food. Sure, the two intervention groups were given direction to either include 4 tbsp of olive oil or 1 ounce of mixed nuts (hazelnuts, walnuts, and almonds), but both groups also increased their servings of legumes and fish, along with the nuts and olive oil. It adds more support to what many nutrition and health experts have been saying for years – focus on overall diet, not just a specific food or nutrient – can be a powerful tool in preventing CVD.
Estruch et al (2013). Primary Prevention of Cardiovascular Disease with a Mediterranean Diet. N Engl J Med 2013 Feb 25. [Epub ahead of print]