Peanuts Rival Fruit As Source Of Health-promoting Antioxidants, Researchers Say

Not only do peanuts contain the so-called “good” kind of fat, but University of Florida researchers have found they also are high in a wide variety of helpful antioxidants, rivaling the fruits often sought out by health-conscious consumers.

“When it comes to antioxidant content, peanuts are right up there with strawberries,” said Steve Talcott, an assistant professor of food science and human nutrition at UF’s Institute of Food and Agricultural Sciences. “We expected a fairly high antioxidant content in peanuts, but we were a bit shocked to find that they’re as rich in antioxidants as many kinds of fruit.”

Talcott and other UF researchers tested the antioxidant content of a dozen different peanut varieties in a study published recently in an issue of the journal Food Chemistry dated May 2005.

Antioxidants are chemicals that block the aging effects of free radicals – unstable molecules naturally occurring in the human body that damage living cells. The damage caused by free radicals has been linked to heart disease, stroke, certain cancers and macular degeneration of the eye.

The growing reputation of antioxidants has led an increasing number of people to include more fruits in their diets, particularly those that are orange or red in color, because such foods have been found to be rich in the health-promoting chemicals. Vitamins A, C, and E are recognized as antioxidants, and polyphenols – a family of chemicals commonly found in foods – also have strong antioxidant properties. Peanuts are a good source of Vitamin E, but in the past they typically have not been considered an antioxidant-rich food, largely because of a lack of data on their polyphenol content.

Now UF researchers have found that peanuts contain high concentrations of polyphenols– chiefly a compound called p-coumaric acid. And they found that roasting can increase the level of p-coumaric acid in peanuts, boosting their overall antioxidant content by as much as 22 percent.

“If you compare them (peanuts) to other foods people think of as rich in antioxidants – mostly fruits and berries – peanuts come out somewhere in the middle,” Talcott said. “They’re no match for the foods at the top of the scale, such as pomegranate, but they do rival other foods that people eat just for their antioxidant content.”

Talcott said roasted peanuts are about as rich in antioxidants as blackberries or strawberries, and are far richer in the chemicals than fruits such as apples, carrots or beets.

The findings add to the growing reputation peanuts are getting for their healthy benefits.

“We already know from previous studies that including peanuts and peanut butter in a healthful diet can lower cholesterol, help people lose weight and prevent type 2 diabetes,” said Kristen Ciuba, a nutritionist for the Peanut Institute, a nonprofit organization in Albany, Ga., funded by the peanut industry.

The UF researchers’ findings were part of a broader study designed to measure the nutritional differences between traditional peanut breeds and the growing number of high oleic peanuts now available to peanut growers.

Oleic acid is a monounsaturated fat, part of a family of chemicals sometimes referred to as “good” fat. A diet rich in oleic acid is believed to lower cholesterol levels and reduce the chance of heart disease. In recent years, UF and a handful of other universities have bred new peanut varieties that have higher-than-average levels of oleic acid.

High-oleic peanuts also have a far longer shelf life than other peanuts, largely because oleic acid doesn’t oxidize as rapidly as other kinds of fat. Talcott and his fellow researchers thought that the peanuts’ high antioxidant content might be responsible for that effect, but their tests showed no significant differences in antioxidant content between high-oleic and traditional peanuts.

Agronomy professor Dan Gorbet, who heads UF’s peanut-breeding program, said it should be possible to breed the nuts with high antioxidant levels in mind.

“It’s certainly worth looking into further,” said Gorbet, a co-author of the study. “The big question is not whether it can be done – the question is whether the demand is there. So far, people haven’t been seeking out peanuts for their antioxidant content, but maybe in the future they will be.”