Dr. Roach: How certain diets lower heart disease risk

Dear Dr. Roach: Which diet styles in particular are associated with a lower risk of heart disease? Many people are confused about what actually is a healthy diet. Is a Mediterranean diet easier than an extreme low-fat diet?

— D.H.H.

Dear D.H.H.: 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 have shown benefit and a few that have shown 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 1 cup of milk a day only) and no more than 10% fat (the average American diet is 30% to 35% fat).

In addition to diet, participants performed aerobic exercise (three hours per week), stress management (1 hour per day) and group psychosocial support (four hours twice a week), and they also had a 100% 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% 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% 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).

Consequently, I recommend against following this type of diet and remind readers that weight loss does not necessarily translate into better health. The changes you make do not need to be extreme in order for you to get better health.

Readers may email questions to [email protected].