How Certain Diet Styles Work to Lower Heart Disease Risk

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% fat (the average American diet is 30% to 35% 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% 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