Peanuts may reduce the risk of death from heart disease, a large study found, suggesting that the health benefits of this low-cost nut may be similar to pricier options like almonds and pistachios. 

While previous studies have linked nut consumption to a lower risk of heart disease, diabetes, and high blood pressure, the earlier research focused mostly on wealthier white people in the U.S. and Europe. This study, with a more ethnically and economically diverse population in the U.S. and China, suggests that nuts can benefit people from a wide variety of backgrounds.

"We can now tell people that peanuts are just as good as more expensive tree nuts, and that the benefit isn't just for white, upper class people, it's for everybody," said senior study author Dr. Xiao-Ou Shu, a professor of epidemiology at Vanderbilt University School of Medicine in Nashville, in a phone interview.

Shu's team studied 71,764 people in the southeastern U.S. – mostly low-income, and about two-thirds African-American – and 134,265 residents of Shanghai.

They looked at how many grams of peanuts (including peanut butter) and other nuts participants ate on an average day and sorted them into five groups ranging from a low of less than 0.95 grams to a high of at least 18.45 grams.

A peanut – which is technically not a nut (it’s a legume) - weighs about one gram, and there are about 28 peanuts in a one ounce serving.

The Chinese participants ate far fewer nuts than the Americans, and in both countries women generally ate less than men. Average daily nut consumption ranged from a low of 1.6 grams for Chinese women to a high of 16.4 grams for white men in the U.S. south.

In the American study, half the people were tracked for at least five years. In the Chinese group, half were tracked for six to 12 years. For the Americans, the risk of dying from any cause was 21 percent lower in the group that ate the most peanuts, compared to the group that ate the least. For the Chinese, the risk reduction was 17 percent.

Nuts and peanuts also lowered the risk of death from strokes and heart disease in both study groups, but not the risk of death from cancer or diabetes.

Peanut butter didn't curb the risk of death, however, possibly because it contained sugar or hydrogenated fat “or some other added ingredients that nullified the benefit," said Dr. David Maron, director of preventive cardiology at Stanford University School of Medicine, who wasn’t involved in the study.

Natural peanut butter, which has no added ingredients, might be just as beneficial as peanuts, Maron said in a phone interview.

The study didn't randomly compare peanut eaters to people who don't eat peanuts, which is the gold standard method for proving a benefit. An observational study like this can’t prove that eating peanuts caused people to live longer. Still, the results, added to findings from previous research, make a compelling argument for including nuts in a healthy diet, said Dr. Mitchell Katz, director of the Los Angeles County Department of Health Services, who wrote a commentary published with the study in JAMA Internal Medicine.

"Because most of the previous research was done on people of high socioeconomic status, there has been an assumption that maybe people who eat nuts are also doing other things that might help them live longer, like exercising more or following a healthier diet," Katz told Reuters Health by phone. "This study tells us that the nuts are beneficial, and it's not just because of the type of people who eat the nuts."

Dietary guidelines emphasizing low-fat foods may have led some people to avoid nuts, even though the kind of fat in nuts is healthy, said Dr. Ethan Weiss of the Cardiovascular Research Institute at the University of California, San Francisco, who wasn’t involved in the study.

"We have forever been told not to eat nuts because (they’re) fatty and high in calories, but that is getting blown up," Weiss said by phone. "It now turns out that it is really good for you to eat nuts and peanuts."