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Diet rich in fruits and veggies lowers blood pressure, touts MED prof's new book

By David J. Craig

Losing weight and reducing salt intake have been well-known for decades for lowering blood pressure, but it was not until the publication of a groundbreaking study by Thomas Moore in 1997 that other dietary factors were proven to reduce hypertension.

	Thomas Moore, M.D., the assistant provost for clinical research at Boston Medical Center, director of the BMC Office of Clinical Research, and a School of Medicine professor, has written a book showing how to reduce blood pressure naturally. Photo by Kalman Zabarsky

Moore, the assistant provost for clinical research at Boston Medical Center, director of the BMC Office of Clinical Research, and a School of Medicine professor, found that eating a diet rich in fruits, vegetables, and low-fat dairy products lowers blood pressure regardless of whether people lose weight or eat less salt. And he showed in a follow-up study last year that the diet -- dubbed Dietary Approaches to Stop Hypertension (DASH) -- is particularly effective when salt intake is reduced as well.

Moore's organic approach to lowering blood pressure is laid out in easy-to-understand terms in a new book he coauthored with several medical researchers, The DASH Diet for Hypertension: Lower Your Blood Pressure in 14 Days -- Without Drugs (2001, The Free Press). Included are detailed discussions about the causes of hypertension and its health effects, the scientific evidence upon which the diet is based, and suggestions for meal plans and 62 recipes created by a team of nutritionists. The advice in the book is recommended by the American Heart Association and has been incorporated into the nutrition guidelines of the National Institutes of Health and the World Health Organization.

"The first question most people ask is how does the diet work, and I simply don't know," says Moore, who came to BU last year from Brigham and Women's Hospital, where he worked as a member of the Harvard Medical School faculty when the 1997 study was published. "The diet essentially looks like the traditional food pyramid, except that there are more fruits and veggies. That's what we tested, and that's what we found works."

In 1994, Moore and researchers from several other institutions set out to test the effect on blood pressure of a number of key nutrients -- minerals such as potassium, calcium, and magnesium, for example -- that were thought might lower blood pressure. For eight weeks 459 subjects followed one of three diets: a typical American diet, a diet with slightly more fruits and vegetables, and what came to be known as the DASH diet -- one rich in fruits, vegetables, and low-fat dairy products, moderate in fish and poultry, and low in red meat and sweets.

Participants on the DASH diet reduced their average systolic blood pressure -- the larger number in a blood pressure reading -- by five and a half points and their diastolic pressure by three points, while the blood pressure of those on the fruit and vegetable diet fell only half as much. The reductions, which occurred in the first two weeks, were most dramatic among those suffering hypertension -- their systolic pressure fell an average of 11 points and their diastolic an average of 6. (Last year's follow-up showed that people on the DASH diet could reduce their systolic blood pressure by 9 points, on average, if they also significantly reduced salt intake, and by 12 points if they had hypertension.)

"Our research team did a quality-of-life survey at Duke University and also found that people reported feeling better after being on the diet," Moore says. "You might expect people would be resentful and grouchy if they had to eat celery all day, but this isn't like eating celery, and that didn't happen."
A typical day on the DASH diet, in fact, might feature for breakfast a bowl of cereal with skim milk and fresh fruit, with a six-ounce glass of fruit juice; a sandwich with two ounces of lean meat and low-fat cheese, two servings of vegetables and one serving of fruit for lunch; at dinner a four-ounce serving of meat, two servings of pasta or rice, three servings of vegetables, a cup of fruit juice, and skim milk; and snacks during the day consisting of unsalted nuts and unsalted light popcorn.

"It's probably the total mix of things in our diet that contributes to lowering blood pressure and cholesterol," says Moore. "There are a lot of people who watch what they eat and eat generally healthy foods, but if even you cut out fatty foods it may not add up to the benefits of the DASH diet if you don't eat the right combination of foods.

"I think the reason the diet is so popular," he adds "is that there is overwhelming scientific evidence that it works and because it's so easy to understand. It doesn't require reading the labels of everything you eat; rather, you just need to keep track of whole foods."

Popular the diet is. Less than five years after Moore published his original study, its findings, he says, are the center of many nutritionists' dietary guidelines, and an Internet search for DASH diet finds about 44,900 applicable Web sites.

Moore says the effect of the diet on blood pressure "is comparable" to that of typical hypertensive drugs, which "are expensive and have a list of side effects as long as your arm." Doctors, meanwhile, "tend to jump straight to medicine because they're not optimistic about people's ability to change their behavior." The diet also was found to lower cholesterol -- by 14 percent, on average.

"There are 50 million people in this country with high blood pressure, and by age 65 half or more of all Americans have high blood pressure," he says. "So even if you don't have hypertension now, the diet is useful because by following it you may never get to the point where a doctor tells you that you have to go on pills."

Moore currently is launching a trial of an online nutrition and exercise program he developed. He hopes to determine the best way to deliver lifestyle advice. Once a week for 12 months nearly 4,000 employees at EMC, a Boston IT company, will be given advice on eating and exercising. The effect of the program will be measured by dietary and blood pressure surveys.

For more information on the DASH diet, including sample menus, visit www.dashforhealth.com.

8 February 2002
Boston University
Office of University Relations