ALBANY, Ga., April 10 /PRNewswire/ -- A new study shows that regular consumption of peanuts lowers triglycerides and improves total diet quality by increasing nutrients associated with the prevention of cardiovascular disease, including magnesium, folate, vitamin E, copper, arginine and fiber. The study is published in the April 2003 issue of Journal of the American College of Nutrition.
Researchers at Purdue University studied the effects of daily peanut consumption on well-known risk factors for cardiovascular disease. One of the principle investigators, Dr. Richard Mattes, Department of Foods and Nutrition, Purdue University, says, "We wanted to determine the impact of peanut consumption on total diet quality. We found that including peanuts in the diet significantly increased magnesium, folate, fiber, copper, vitamin E, and arginine consumption, all of which play a role in the prevention of heart disease." These findings are consistent with several clinical and epidemiological studies, such as the Nurses Health Study, that show that people who consume about one ounce of peanuts, nuts and peanut butter per day improve blood lipid levels and decrease risk of cardiovascular disease.
Because peanut consumption in the United States is greater than the consumption of all other nuts combined, it is important to observe the effects of incorporating peanuts into the daily diet. The study included fifteen healthy men and women who were each put on three different diets that included a research-sized portion of approximately 500 calories of peanuts. The first treatment was a Free-Feeding diet, which involved including 500 calories of peanuts without any dietary guidance. The second Addition treatment entailed adding 500 calories of peanuts to each participant's usual diet. The third Substitution treatment had participants substitute peanuts for 500 calories from fat in their usual diet.
Elevated triglycerides is an emerging risk factor for heart disease. In this study, triglycerides were lowered in all treatment groups and were significantly lower in the Addition and Substitution groups at 24 and 18 percent respectively. This could translate into an 8 and 6 percent decrease in risk of cardiovascular disease. These findings are consistent with a previous clinical study at Penn State University (American J of Clinical Nutrition, 1999) that found a 13% decrease in triglyceride levels when participants consumed a diet with peanuts and peanut butter, compared to the average American diet.
Increased Magnesium Levels
Increased levels of serum magnesium help to inhibit platelet aggregation and activity, known risk factors for heart disease. It has been shown that the risk of cardiovascular disease increases with magnesium concentrations below 0.81 mmol/L. Importantly, during the Free-Feeding treatment, each of the six subjects with magnesium concentrations below 0.81 mmol/L improved their status. In fact, a significant increase in serum magnesium levels was observed across all treatments (average increase from baseline was 58 percent). The authors observe that peanut consumption may be an effective way to increase magnesium status and thereby reduce cardiovascular disease risk.
Better Diet Quality
Peanuts are also a good source of vitamin E, copper, arginine, and fiber, all nutrients with cardiovascular disease-reducing properties. Dietary intakes of fiber, vitamin E and copper increased, and the ratio of lysine to arginine decreased significantly from baseline in all treatments. Dietary folate also increased in all treatments, as expected, since peanuts are a good source of folate.
Throughout the study, peanut consumption led to favorable changes in the fat profile of the diet: saturated fat decreased and unsaturated fat increased as a portion of calories. Recent National Cholesterol Education Program guidelines recommend limiting saturated fat and refined carbohydrates and replacing them with healthful unsaturated fats such as those found in foods like peanuts, nuts, peanut butter and vegetable oils.
The study was funded by a grant from the U.S. Agency for International Development. The Peanut Institute is a non-profit organization that supports nutrition research and develops educational programs to encourage healthful lifestyles. For more information on peanuts and health, visit www.peanut-institute.org