Issue 131 Item 5 Short-term Diet & Exercise Cut Heart Risk

People at risk for heart disease can lower their risk dramatically and quickly with exercise and dieting, that from a current study. Researchers found that 11 obese men who consumed a low-fat, high-fiber diet and exercised daily for 3 weeks lowered their blood pressure and cholesterol levels, reduced the amount of stress on their hearts, and improved other heart disease risk factors even though they lost only a small amount of weight.

"You can lose weight over time, but fortunately we can ease high blood pressure and the risk of atherosclerosis and heart disease while, or even before, you shed extra pounds," lead author Dr. R. James Barnard from the University of California.

The men in the study ranged from 38 to 72 years old and were all considered obese, with a body mass index (BMI) of at least 30. BMI is a measure of weight in relation to height and is thought to more accurately correlate with the risk of heart disease than weight alone.

Study volunteers walked briskly on a treadmill each day for 45 to 60 minutes and consumed a diet in which less than 10% of total calories came from fat, 15% to 20% from protein, and up to 75% from fiber-rich carbohydrates such as whole grains, fruits and vegetables. The meals were served buffet style and study volunteers were allowed to eat as much as they wanted.

After 3 weeks, oxidative stress–which refers to levels of disease-causing free radicals in the blood–fell by an average of 28%, according to the report in the November 12th rapid access issue of Circulation Journal of the American Heart Association. Levels of nitric oxide, a blood compound that keeps blood vessels clear and helps them to dilate, rose by 28%.

Overall, total cholesterol fell by nearly 20%. Blood sugar and insulin levels–risk factors for type 2 diabetes as well as heart disease–fell by 7% and 46%, respectively.

The researchers attribute the results to increased intake of fiber and antioxidants, which are compounds in fruits and vegetables that neutralize free radicals in the body. Lower levels of fat and refined sugar contributed to reductions in insulin, blood pressure and oxidative stress. Exercise may have improved levels of nitric oxide and lowered insulin and blood pressure.

The results of the current study on men may also apply to women, Barnard said. He described the results of another study not yet published showing that oxidative stress and other heart disease risk factors were mitigated by a short-term diet and exercise program in postmenopausal women, including those taking hormone replacement therapy.

The results support the recent American Heart Association dietary recommendations focusing on whole grains, vegetables and fruits and also point out the value of daily exercise.
Circulation 2002;106