July 31, 2003
Eating peanuts helps keep heart healthy without weight gain
WEST LAFAYETTE, Ind. Adding peanuts to that apple a day that keeps the doctor away is a good way to stay heart-healthy and trim, says a Purdue University professor.
Research by Richard Mattes, professor of foods and nutrition, and his doctoral student, Corinna Alper, proves regular peanut consumption helps reduce the risk of cardiovascular disease without weight gain.
"Peanuts are the most widely consumed nut in this country," Mattes said. "They are a rich source of monosaturated fatty acids, magnesium and folate, vitamin E, copper, arginine and fiber, all of which have cardiovascular disease risk-reducing properties."
Mattes said the findings are consistent with several epidemiological and clinical studies.
"Peanuts, which are actually legumes, are often viewed as unhealthy because they are high in fat," said Mattes. "This is the biggest obstacle in peanut consumption.
"But peanuts are rich in the types of fats that actually reduce cardiovascular disease risk and have strong satiety properties meaning a person feels full after eating peanuts so they do not pose a threat of weight gain. People can feel comfortable including them in their diet to take advantage of peanuts' reducing the risk of heart disease, without adding to body weight."
Mattes and Alper conducted three trials in the study. The first trial entailed having participants reduce dietary fat intake by 500 calories and replace them with 500 calories of peanuts, so total calories did not change. Only the source of those calories did.
In the second trial, individuals consumed their regular diet and added 500 calories of peanuts, which boosted total caloric intake. In the third treatment, individuals were allowed to incorporate peanuts in their diets in any way they chose.
In all three groups, subjects' triglyceride level a risk factor for cardiovascular disease was lowered significantly.
"We have learned that regular peanut consumption lowers triglyceride levels by as much as 24 percent even in the group where peanuts were added to regular dietary intake," Mattes said. "We also saw no significant change in body weight, despite adding 500 calories of peanuts a day for eight weeks.
"Of course, we want to know where those calories went. There are three possible answers to that question."
The first is that peanuts have a high satiety value, and that feeling of being full reduces the amount a person eats. Mattes said this accounts for the largest portion of missing calories.
The second possibility is that the peanuts trigger an increase in people's resting metabolic rate. The third explanation is that people don't chew nuts well, so people's bodies fail to absorb a portion of nuts' caloric energy.
"There is great public health significance to work in this area," Mattes said. "This particular study indicates it may be an appropriate health recommendation to include peanuts in the daily diet."
The study was funded by a grant from the United States Agency for International/National Development.
Mattes' team also conducts research in Ghana and Brazil, so he sees the peanut research findings have global value. "There is great opportunity for the peanut industry in developing countries," Mattes said. "Peanuts have a long shelf life and are rich in nutrients."
Mattes' study, "Peanut Consumption Improves Indices of Cardiovascular Disease Risk in Healthy Adults, " was published in the April 2003 issue of the Journal of American College of Nutrition. In addition to this study, Mattes is doing research on identifying how the energy from peanuts is used and whether the healthful properties of peanuts are due to their oil content.
Writer: Amy Patterson-Neubert, (765) 494-9723, firstname.lastname@example.org
Source: Richard Mattes, (765) 494-0662, email@example.com
Purdue News Service: (765) 494-2096; firstname.lastname@example.org
Corinna A. Alper and Richard D. Mattes
Diets containing nuts reduce cardiovascular disease risk factors. This has primarily been attributed to their fatty acid compensation, but other constituents may also contribute. Peanuts, the most widely consumed nut (actually a legume), are a rich source of monosaturated fatty acids, magnesium and folate, but their effects on cardiovascular disease risk factors are poorly characterized. This study determined the effects of chronic peanut consumption on diet composition as well as serum lipids, magnesium and homocysteine concentrations in free-living subjects under different conditions of peanut intake. Regular peanut consumption lowers serum triacylglycerol, augments consumption of nutrients associated with reduced cardiovascular disease risk and increases serum magnesium concentrations.