Peanuts are not nuts but are actually legumes related to peas, beans and lentils. The health advantages of peanuts are similar to other legumes: They are good sources of vitamin E, niacin, folate, protein and manganese. Peanuts are a source of tryptophan, which the body uses to produce serotonin. Though peanuts are high in fat, they contain good fats that are actually heart healthy. A Nurses' Health Study, which involved more than 86,000 women, found that eating peanuts regularly is linked with lowering the risk of cardiovascular disease.
Peanuts are rich in monounsaturated fats, the so-called good fat. To be more specific, peanuts contain oleic acid, the beneficial fat found in olive oil and emphasized in the Mediterranean diet. Eating peanuts or peanut butter is associated with not just lower cholesterol but lower levels of LDL, the 'bad' cholesterol. A diet high in monounsaturated fat such as the kind found in peanuts is believe to lower the risk of cardiovascular disease by as much as 21 percent.
Peanuts are also a significant source of antioxidants, particularly resveratrol. This is the same phenolic antioxidant in red grapes and wine that is credited with the low incidence of cardiovascular disease in France despite the high-fat diet that is consumed by many who live there. According to a study on animals published in the Journal of Agricultural and Food Chemistry, resveratrol has been shown to increase blood flow to the brain by up to 30 percent, which reduces the risk of having a stroke.
Polyphenols, another class of antioxidants, are also found in peanuts. Though peanuts don't contain these important nutrients in the same density as the riches sources such as blackberries and strawberries, they have far more than several other fruits and vegetables. Polyphenols prevent and repair the degenerative effects of free radicals, stress and aging. A study at the University of Florida finds that roasting actually increases peanuts' total antioxidant content by up to 22 percent.
Despite the high-fat content of peanuts and their caloric density, studies consistently find that people who eat nuts regularly are actually less likely to gain weight than those who do not. One theory is that because peanuts and peanut butter produce a longer feeling of satiety than many other kinds of foods, people are able to eat a small amount and still feel full. A study in Spain showed that people eating nuts at least two times per week were 31 percent less likely to gain weight than other participants in the study. These results neutralize one of the greatest concerns about peanuts, namely that they are not an effective factor in cardiovascular health because they lead to weight gain.
Peanuts rate low on the glycemic index, which means they are even safe for diabetics and others who are concerned about sharp spikes in blood sugar. Because the energy in peanuts is released slowly, there is not a spike or subsequent crash in serum glucose levels. The caloric density, however, ensures that steady energy is supplied for a considerable period of time.