BETHESDA--The combination of vigorous exercise with either vegetarianism or moderate alcohol intake helps to reduce the risk factors of coronary artery disease (CAD) beyond those obtained from diet alone, according to a new study of 351 vegetarian and 8,891 nonvegetarian runners.
The research, from the National Runners Health Study, appears in the November issue of the American Journal of Clinical Nutrition, the peer-reviewed publication of the American Society for Clinical Nutrition.
"The benefits of running on coronary artery disease risk in vegetarians is poorly understood," said investigator Paul T. Williams, Ph.D., of the Life Science Division, Lawrence Berkeley National Laboratory, Berkeley, California. "Although vegetarians and vegans are minorities among Americans, they represent a significant portion of the world's people. Even among non-vegetarians, the interactive effects of diet and exercise on CAD risk factors have not been examined in a large vigorously active sample."
According to study results, vegetarians had lower body mass indexes (a measure of body fat), and smaller hips than nonvegetarian runners. In addition, male vegetarians, as contrasted to nonvegetarian runners, had smaller waists, less total cholesterol and less low-density lipoprotein (LDL) cholesterol (the "bad" cholesterol that increases the risk of heart disease).
"Previous research has shown that vegetarian diets were also associated with lower levels of high density lipoprotein (HDL) cholesterol (the "good" cholesterol associated with less heart disease), increasing the risk of coronary artery disease," said Dr. Williams. "Our research shows that in both nonvegetarians and vegetarians running appears to increase HDL-cholesterol levels. Thus, by vigorous exercise, vegetarians can avoid having low HDL-cholesterol while retaining the health benefits of their diet."
"Our findings also suggest that running and alcohol contribute independently and additively in the production of higher HDL-cholesterol concentrations in runners," said Dr. Williams. "At every running level, HDL-cholesterol went up in association with the number of drinks consumed per week. Similarly, at all levels of alcohol consumption, HDL-cholesterol went up in association with the number of miles run.
"The National Cholesterol Education Program has defined as desirable an HDL-cholesterol level of 60 milligrams per deciliter," Dr. Williams added. "Men who ran 45 or more miles per week and who drank 6 ounces of alcohol per week were five times more likely to have this desirable level than non-drinkers running less than 15 miles per week. This level was also found in all the women runners who ran 45 miles per week and consumed 6 ounces of alcohol."
Dr. Williams cautions that he is not recommending that nondrinkers start consuming alcohol. He stresses that his results pertain only to drinking in moderation.
"Please note also," he added, "there is a substantial body of research showing an increase in blood pressure from alcohol consumption in non-runners. In this study, we demonstrated that such increases are not reduced by running."
An unexpected result from the study was the effect of foods on body weight. By running more miles, runners can diminish some of the consequences of eating higher fat foods, according to Dr. Williams.
"In sedentary people, other researchers have shown that higher fat diets often mean higher calorie intake and weight gain," noted Dr. Williams. "We found that diets containing more red meat and less fruit had twice as much impact on weight and waistlines in low-mileage runners than in high mileage runners. This may offer an option for men who can't seem to avoid high fat diets. They can run more. However, as shown by the vegetarians, the best cholesterol profiles are achieved by following both a prudent diet and a physically active lifestyle.
"Official guidelines from the Centers for Disease Control and Prevention emphasize the benefits of walking 10 to 14 miles per week, which is the energy equivalent of running 5 to 7 miles weekly," said Dr. Williams. "Ninety-five percent of the 199 male and 152 female vegetarians exceeded these minimum recommendations and appeared to benefit substantially by exceeding the recommended levels."
Volunteers for the "National Runners Health Study" were recruited through a two-page questionnaire distributed at races nationwide. In addition, runners were enlisted through articles in the nation's largest circulation running magazine ("Runners World," Emmaus, PA). The researchers gathered information on the race, sex, age; running distance and speed; race participation; and body weight, dimensions, and diet (vegetarianism and current weekly intakes of alcohol, red meat, fish, and fruit). The investigators also requested permission to contact the runner's doctor for clinical measurements of height, weight, blood pressure, and lipoprotein cholesterol measurements.
Contact: Paul T. Williams, Ph.D., Life Science Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Building 934, Berkeley, California 94720 Phone: 510-486-5630 Fax: 510-486-5990.
Journal
American Journal of Clinical Nutrition