By Marc Gillinov, MD, Cardiac Surgeon at Cleveland Clinic and StevenNissen, MD, Chairman of the Department of Cardiovascular Medicine at Cleveland Clinic Dr. Gillinov and Dr. Nissen are authors of Heart 411: The Only Guide to Heart Health You'll Ever Need
Hundreds of diet books and thousands of websites promise to deliver the diet that will secure your heart’s health. Proponents of diets defend their choices with unbridled passion. But don’t believe everything that you hear or read. Few of the recommendations are supported by reliable, evidence-based research. The data on diets and heart protection are out there, but you need to know where to look and how to interpret the information once you find it.
We can point you to the best heart diet with one word: Mediterranean.
Following the Evidence
In the 1950s, University of Minnesota researcher Ancel Keys recognized that there was something special going on in the Mediterranean region. In his landmark Seven Countries Study, Keys reported a 20-year analysis of heart disease and dietary habits among 12,000 men from communities in Italy, the Greek islands, Yugoslavia, the Netherlands, Finland, Japan, and the United States. He found that despite a high fat intake, people from the Greek islands had very low rates of coronary heart disease and long life expectancies. He linked this to their diet, and the term Mediterranean diet was coined.
What Is a Mediterranean Diet?
Although more than 15 countries border the Mediterranean Sea, the diets have certain common elements:
- Plant foods: Fresh fruits and vegetables, beans, nuts, seeds, legumes, whole grains
- Olive oil
- Poultry: Moderate amounts
- Eggs: Fewer than four per week
- Dairy: Low-fat offerings, moderate consumption of cheese and yogurt
- Wine: Moderate consumption with meals
- Very little red meat
What is special about this diet? Rich in plant-based foods, it has the best combination of nutrients, with the right fats (mono- and poly-unsaturated fats) and the right carbohydrates (high fiber, whole grain). It is low in saturated fats and refined carbohydrates. Although these are the key features, many people focus on olive oil when discussing the Mediterranean diet.
The “Magic” of Olive Oil
The Mediterranean diet is not a low-fat diet. The primary source of fat, olive oil, is rich in “good” fats, particularly the monounsaturated fat, oleic acid. In some studies, olive oil has been associated with improvements in cardiac risk factors, including decreases in triglyceride levels, inflammation and blood clotting and better blood vessel function. Other research suggests that extra virgin olive oil is the best type, as it may increase HDL cholesterol. We recommend using the cold-pressed, extra-virgin variety as a dressing for salads and vegetables and as a dip for your whole-grain breads. Enjoy the taste and improve your heart health by adding olive oil to a healthy diet plan.
The Mediterranean Diet and Cardiovascular Risk Factors
Carefully controlled scientific studies suggest that following a fruit-, vegetable- and olive-oil-based Mediterranean diet has favorable effects on cardiac risk factors. These include improved cholesterol levels, reduced blood pressure, reduced inflammation, improved insulin sensitivity, and improved blood vessel function.
Although many of these benefits have been ascribed specifically to olive oil, it is difficult to separate out the effects of individual components of the diet. You should think of the Mediterranean diet as a package deal, filled with many tasty, healthy choices.
Olive oil is best in the context of this diet, rather than as an add-on to a typical Western diet. Put another way, dressing a dinner salad with extra-virgin olive oil does not “erase” a main course that includes an 18-ounce rib eye steak smothered in blue cheese.
Does the Mediterranean Diet Reduce the Risk of Heart Attack?
So far, the evidence suggests that the answer to this question is “Yes.” In a large observational study of more than 22,000 Greek adults, those adhering to a Mediterranean diet had a reduced risk of dying from heart disease. The same findings hold in the United States, where a 400,000-person study sponsored by the National Institutes of Health and AARP recorded similar cardiac benefits in those following a Mediterranean diet.
To date, we have more data supporting the Mediterranean diet than we have for any other diet when it comes to heart health, although critics are correct in their claim that we do not yet have iron-clad proof that this diet reduces the risks of heart attack and stroke. In fact, no existing study of diet and heart health meets our contemporary gold standard for medical evidence: a large randomized controlled clinical trial. In such a trial, people would be split into groups and randomly assigned to one diet or another (e.g., Mediterranean vs. Atkins). Then, over the course of several years, we would determine which diet was more likely to protect the heart.
Although we don’t yet have that level of evidence, we feel that there is enough scientific study and observational data to lead us to the conclusion that the Mediterranean diet is the best choice for heart health.