Despite their name, peanuts are neither nuts nor peas. They belong to the legume family, which includes lentils, chickpeas and beans. Unlike nuts, which grow on trees, peanuts start growing on the ground and eventually burrow underground, where they mature. Peanuts are nutritionally dense; in fact, peanut butter is often the food of choice in polar expeditions because it is high in protein and calories, and requires no cooking or preparation. Interestingly, while peanuts are rich in fat, the fat they contain is actually heart-healthy. Moreover, although they are high in calories, moderate consumption of peanuts does not contribute to weight gain. According to the January 2011 issue of “Nutrition Metabolism and Cardiovascular Disease,” moderate nut consumption may actually help with weight loss.
Peanuts and Heart Health
In 2008, P.M. Kris-Etherton and colleagues from the Pennsylvania State University carried out a pooled analysis of four epidemiological studies conducted in the United States to investigate the effect of peanut and nut consumption on coronary heart disease. They found that subjects with the highest peanut and nut consumption had an approximately 35 percent reduced risk of coronary heart disease. The authors attribute this to the nuts’ cholesterol-lowering effect and antioxidant and anti-inflammatory properties. Nutrients in nuts and peanuts that may be responsible for these effects include protein, fiber, essential minerals including magnesium, and other beneficial plant compounds, called phytonutrients.
A review paper in the November 2006 issue of the “British Journal of Nutrition,” analyzing 17 different nut-feeding studies, reported that nuts significantly decrease cholesterol levels. While this review was about tree nut consumption, it is expected that the results would be the same if peanuts were consumed. In fact, a 2010 study by M. Ghadimi Nouran and colleagues from the Shahid Beheshti University, Iran, found that subjects consuming 77 g of peanuts with their usual diet for four weeks had a significant improvement in the ratio of their cholesterol levels, reducing the amount of "bad" cholesterol and improving the amount of "good" cholesterol.
Atherosclerosis, or thickening of the arteries, arises when LDL cholesterol in the blood gets oxidized, or ‘damaged,’ by free radicals, which are present in the environment and are also produced by the body. A review paper in the September 2008 issue of the “Journal of Nutrition,” reports that peanuts are rich in vitamin E and phenolic antioxidants, and these prevent LDL cholesterol from being oxidized. Moreover, most of the fat found in peanuts is monounsaturated fat, and this type of fat is not susceptible to oxidation, and, so, does not contribute to atherosclerosis. This is the same type of fat found in olive oil, which is renowned for its heart-protective effects.
Peanuts also contain resveratrol, a particular phenolic compound, which is also found in red wine. Resveratrol is believed to be the reason why moderate consumption of red wine is associated with a decrease in heart disease risk. According to V.R. Ramprasath and P.J. Jones from the University of Manitoba, Canada, resveratrol exerts anti-atherogenic, anti-inflammatory and anti-cancer effects. Ramprasath and Jones report that resveratrol may also prevent platelet aggregation, which is a risk factor for heart attacks and strokes, and may regenerate vitamin E, which further strengthens antioxidant effects.