A review of 25 studies shows that eating nuts (including peanuts) lowers cholesterol to help prevent heart attacks (Archives of Internal Medicine, May 10, 2010). Eating an average of 2.5 ounces of nuts per day lowers total cholesterol 5.1 percent, LDL (the bad cholesterol) 7.4 percent, and triglycerides 10.2 percent. It even lowers Lp(a), a genetic component of cholesterol that increases risk for strokes and heart attacks in young people. The more nuts a person eats, the lower the cholesterol. Those with the highest bad LDL cholesterol had the greatest lowering when they ate nuts.

An earlier review of five large epidemiologic studies and 11 clinical studies showed that eating nuts reduces risk for heart attacks (Nutrition Reviews, May 8, 2001). The most improvement came from eating two ounces (four tablespoons) of nuts five or more times a week. Eating an ounce of nuts more than five times a week can result in a 25 to 39 percent reduction in heart attack risk.

Nuts are a rich source of monounsaturated fatty acids. Before the bad LDL cholesterol can form plaques in arteries, it must be converted to oxidized LDL. LDL formed from monounsaturated fat is highly resistant to oxidation, so the LDL is less likely to be converted to its form that damages arteries. The nuts in these studies included almonds, brazil nuts, cashews, hazelnuts, macadamia nuts, pecans, pistachios, walnuts, and peanuts. Among Americans, peanuts account for approximately half of all nuts consumed.