DEAR DR. ROACH: Which diet styles in particular are associated with a lower risk of heart disease? Many people get confused about what a healthy diet actually consists of. Is a Mediterranean diet easier than an extreme low-fat diet? — D.H.H.

ANSWER: There are several styles of diet that have been proven to be healthier than a typical North American diet. Two of the best that have been studied are the ones you mentioned — the extreme low-fat diet and the Mediterranean-style diet — but there are many others that show benefit and a few that show harm.

In a landmark study published by Dr. Dean Ornish in 1998, intensive lifestyle changes reduced the amount of heart disease (measured by blockages in the heart arteries) more than those in the control group without medication. This remarkable result required a diet that was mostly vegetarian (egg whites and only 1 cup of milk a day) and no more than 10 percent fat (the average American diet is 30 percent to 35 percent fat).

In addition to dietary changes, participants performed aerobic exercise (3 hours per week), stress management (1 hour per day) and group psychosocial support (4 hours twice a week), and they also had a 100 percent smoking cessation rate. It is unclear how much of the benefit in reversing heart blockages is due to diet and how much is due to other beneficial behavior changes, or whether they all worked together (which seems likely to me).

The Mediterranean diet, when studied, also reduced risk of heart disease, with a roughly 30 percent relative-risk reduction in heart attack, stroke or death due to heart disease. This diet is characterized by:

— An abundant use of olive oil

— High consumption of plant foods (fruits, vegetables, legumes, cereals, nuts and seeds)

— Frequent but moderate intake of wine (especially red wine) with meals

— Moderate consumption of fish, seafood, fermented dairy products (yogurt and cheese), poultry and eggs

— Low consumption of red and processed meat as well as sweets

There isn’t a doubt that the Mediterranean diet is much easier for most to comply with. The two diets haven’t been compared, so I can’t say which is better, but I more commonly recommend the Mediterranean diet. However, I do not recommend drinking wine for any kind of health benefit. Exercise, stress management and psychosocial support would be likely to improve outcomes with any kind of favorable dietary change.

The DASH diet — a lower-salt diet with 4 to 5 servings of fruit, 4 to 5 servings of vegetables and 2 to 3 servings of low-fat dairy per day, with less than 25 percent of daily caloric intake from fat — has been shown to reduce blood pressure. Moreover, in people with high or normal blood pressure, this diet lowers risk of colorectal cancer, cardiovascular disease and premature mortality. It’s also easy to maintain.

Many people ask me about ketogenic (“keto”) diets, which typically involve large amounts of meat and, consequently, a high proportion of protein and fat. Although these types of diets can cause short-term weight loss, a recent study showed these diets unfortunately increased cholesterol levels and more than doubled the risk of adverse cardiovascular outcomes (heart attack and death).

So, I recommend against following this type of diet and remind readers that weight loss does not necessarily translate into better health. As the above studies have shown, a person of any weight can better their health by having a more plant-based diet, getting regular exercise, managing their stress and receiving psychosocial support. The changes you make do not need to be extreme in order for you to receive better health.

Dr. Roach regrets that he is unable to answer individual questions, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu.

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