Peanut consumption associated with decreased total mortality and mortality from cardiovascular diseases

Researchers at Vanderbilt University and the Shanghai Cancer Institute examined the association of peanut and nut consumption with mortality among low-income and racially diverse populations and found that intake of peanuts was associated with fewer deaths, especially from heart disease.

The study was published March 2 in JAMA Internal Medicine. The first author of the paper is Hung Luu, Ph.D., a post-doctoral fellow in the Division of Epidemiology, Vanderbilt University Medical Center. Senior author is Xiao-Ou Shu, M.D., Ph.D., associate director for Global Health at the Vanderbilt-Ingram Cancer Center (VICC) and professor of Medicine in the Department of Epidemiology.

"Nuts are rich in nutrients, such as unsaturated fatty acids, fiber, vitamins, phenolic antioxidants, arginine and other phytochemicals. All of them are known to be beneficial to cardiovascular health, probably through their anti-oxidative, anti-inflammatory and endothelial function maintenance properties," Shu said.

While research has previously linked nut consumption with lower mortality, those studies focused mainly on higher-income, white populations. This study was the first to discover that all races -- blacks, whites and Asians alike -- could potentially increase heart health by eating nuts and peanuts.

"In our study, we found that peanut consumption was associated with reduced total mortality and cardiovascular disease mortality in a predominantly low-income black and white population in the U.S., and among Chinese men and women living in Shanghai," Shu said.

This study was based on three large ongoing cohort studies. Participants included more than 70,000 Americans of African and European descent from the Southern Community Cohort Study (SCCS), who were mostly low-income, and more than 130,000 Chinese from the Shanghai Women's Health Study (SWHS) and the Shanghai Men's Health Study (SMHS).

Information on nut consumption was collected by structured questionnaires at the baseline survey. For participants in the SCCS, deaths were determined by linking with the National Death Index and Social Security Administration mortality files, and for participants in the SWHS/SMHS, by linking with the Shanghai Vital Statistics Registry and by conducting home visits. In total, more than 14,000 deaths were identified, with a median follow-up of 5.4 years in the SCCS, 6.5 years in the SMHS, and 12.2 years in the SWHS.

Peanut consumption was associated with decreased total mortality, particularly cardiovascular mortality (i.e., 17-21 percent reduction in total mortality, and 23-38 percent reduction in cardiovascular mortality for the highest quartile intake group compared to the lowest quartile group) across all three racial/ethnic groups, among both men and women, and among individuals from low-SES groups.

Because peanuts are much less expensive than tree nuts, as well as more widely available to people of all races and all socioeconomic backgrounds, increasing peanut consumption may provide a potentially cost-efficient approach to improving cardiovascular health, Shu said.

"The data arise from observational epidemiologic studies, and not randomized clinical trials, and thus we cannot be sure that peanuts per se were responsible for the reduced mortality observed," said William Blot, Ph.D., associate director for Cancer Prevention, Control and Population-based Research at VICC and a co-author of the study.

He did note that "the findings from this new study, however, reinforce earlier research suggesting health benefits from eating nuts, and thus are quite encouraging."

The American Heart Association recommends eating four servings of unsalted, unoiled nuts a week. However, nutrient-rich nuts are also high in calories, so don't eat too many if you're watching your weight. A serving size is a small handful or 1.5 ounces of whole nuts or 2 tablespoons of nut butter.