What you eat has shown to have a significant impact on your risk of heart disease. Unfortunately, its not all that clear which dietary approach is best. One popular approach is the Mediterranean diet, which encourages a high intake of olive oil, poultry and fish, fruits, vegetables, and nuts. The diet also limits the amount of red meats, dairy, and sweets that you eat. Research has suggested that this diet provides heart health benefits but it is not clear which part of the diet provides most benefits or if it is the diet as a whole that is needed.
Spanish researchers developed a randomized trial to determine if the Mediterranean diet with focus on olive oil or nuts can help prevent cardiovascular events in people at high risk. The trial, published in the New England Journal of Medicine, found that the Mediterranean diet was associated with a lower risk of stroke in people with high risk of cardiovascular disease.
The randomized trial included 7,447 participants aged 55-80 years who did not have cardiovascular disease but had an increased risk of developing it. Participants were considered to be high risk if they had type 2 diabetes or three or more other risk factors such as smoking, high blood pressure, high cholesterol or obesity. They were randomized to one of three groups:
- Mediterranean diet supplemented with extra-virgin olive oil
- Mediterranean diet supplemented with mixed nuts
- Control diet—advice to reduce fat in diet but no specific plan provided
Participants were followed on average of 4.8 years for any cardiovascular events such as heart attack, stroke, or death from cardiovascular event. Participants taking the Mediterranean diet along with either extra-virgin olive oil or nuts had a significantly decreased risk of stroke compared to participants in the control group.
There was no significant difference in rates of heart attack, death due to cardiovascular events, or death from any cause.
A randomized controlled trial is considered a reliable form of research. There were a couple of problems with the study that may affect its reliability. The control intervention was changed after the first couple of years to match the amount of attention received by other participants. The lack of attention in first couple of years may have decreased benefits in the control group. More participants also dropped out of the control group than either group on the Mediterranean diet. This can exaggerate or underestimate the difference between the groups.
This study showed that even though the participants did not decrease their overall fat intake, they were able to reduce their risk of stroke with Mediterranean based diet. Both olive oil and nuts along with the rest of the Mediterranean diet may have played an important role in this risk reduction. If you are interested in decreasing your risk of stroke a Mediterranean diet with olive oil and nuts may be a good option for you. However, keep in mind that olive oil and nuts should be used in moderation since they are high in calories. It can be difficult to make major changes in your diet. Begin by introducing elements of the Mediterranean diet into your daily meals. Replace cooking oils and dressing with olive oil based ones and consider nuts for snacks. Replace red or processed meats with fish or chicken. If you are at high risk for cardiovascular disease, talk to your doctor or meet with a dietitian to plan effective dietary changes.
Estruch R, Ros E, et al. Primary Prevention of Cardiovascualr Disease with a Mediterranean Diet. N Engl J Med. 2013 Feb 25 early online.
Last reviewed March 2013 by Brian Randall, MD
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