Weight-Loss Diet Reduces Blood Pressure

Weight-loss diets that emphasize eating more fruits, vegetables, and low-fat dairy products may lower blood pressure more effectively than fat-restricted diets do, reports the American Journal of Clinical Nutrition (2005;81:983–9).

High blood pressure, or hypertension, is defined as a systolic blood pressure (the top number of a blood pressure reading) of 140 mm Hg or greater, and/or a diastolic blood pressure (the bottom number of a blood pressure reading) of 90 mm Hg or greater. Uncontrolled hypertension can lead to hardening of the arteries (atherosclerosis), heart attack, stroke, heart failure, and damage to other organs including the kidneys and eyes. Each year, more than 20,000 Americans die from hypertension-related causes.

Although high blood pressure may be related to underlying disease processes, usually a single cause cannot be identified. Hormones, heredity, stress, diet, defects in sodium excretion, and especially being overweight may all play a role in hypertension development.

For those with hypertension, restricting salt in the diet, losing weight, and exercising may help to reduce blood pressure. Drug treatments focus on decreasing the volume of blood in the body and dilating blood vessels. Diuretics such as hydrochlorothiazide help to rid the body of excess water and other medications help relax the muscles in artery walls, allowing blood to flow through the blood vessels more easily. Commonly, two or more medications are needed to help control high blood pressure. Unwanted side effects of various blood pressure medications may include depletion of essential minerals such as potassium and magnesium, cough, and impaired sexual function.

Previous studies have shown that incorporating potassium-rich foods, such as fruits and vegetables, into the diet may have a blood pressure–lowering effect. The new study compared the effects of two different weight-loss diets on blood pressure in 54 overweight men (average age 48 years). The participants were instructed to follow either a low-fat diet (LF) or a low-fat, high-fruit-and-vegetable diet (FV) for 12 weeks. All participants engaged in moderate-intensity exercise for at least 30 minutes on most days of the week.

Men in the FV group were told to eat four or more servings of fruit (one serving equaling one medium piece of fruit or one cup of fruit juice), four or more servings of vegetables (one serving equaling one-half cup cooked vegetables, one cup salad, or one potato), and three or more servings of low-fat dairy products (one serving equaling one cup of milk or yogurt, or one-half cup ricotta cheese) each day. In addition, they were advised to eat one four-ounce serving of fish, one cup of cooked legumes (beans), and one ounce of unsalted seeds and nuts each week, and to avoid butter and salty foods. Red meat intake was limited to two four-ounce servings per week.

The LF group was counseled to decrease total fat and saturated fat intake, limit high calorie foods and drinks, consume mostly plant-based foods, eat low-fat dairy products, limit cheese and ice cream intake, avoid fried foods, and eat lean meats.

At the beginning and end of the study, height, weight, and blood pressure were measured. The participants monitored their blood pressure at the same time each day from home and completed dietary records and food frequency questionnaires to assess nutrient intake.

Both of the diets led to a weight loss of about 11 pounds. The FV diet, however, was associated with a significantly greater drop in blood pressure than was the LF diet. Respectively, systolic and diastolic blood pressures fell by about five and four mm Hg more in the FV group than in the LF group. Over the course of the study, participants in the FV group ate significantly more fruits, vegetables, and low-fat dairy products than they did at the beginning of the study. This group also consumed significantly less fat and sodium, and more potassium, calcium, and magnesium than did the LF group.

These results suggest that a weight-loss diet that emphasizes fruits, vegetables, and low-fat dairy products may result in greater reductions in blood pressure than a fat-restricted diet does alone. It is not clear which factors are responsible for these effects, but it is possible that the effects may be attributable to lower sodium intake coupled with higher intakes of potassium, calcium, and magnesium-rich foods.

Kimberly Beauchamp, ND, received her bachelor’s degree from the University of Rhode Island and her Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. She is a co-founder and practicing physician at South County Naturopaths, Inc., in Wakefield, RI. Dr. Beauchamp teaches holistic medicine classes and provides consultations focusing on detoxification and whole-foods nutrition.

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