Researchers at Vanderbilt University and the Shanghai Cancer Institute examined nut and peanut intake and mortality in three separate groups over an average of six years and found lower rates of death, especially from heart disease. The study was published online this week in JAMA Internal Medicine.
Studies for the last few decades have probed the question of whether and how nut and peanut intake reduces the chances of death from cardiovascular diseases and other illnesses, such as cancer. But the new study’s senior author, Dr. Xiao-Ou Shu, said this most recent investigation is important because it focuses on low-income and racially diverse populations – a group of primarily African-American and low-income people in the United States, two groups of people in Shanghai, China – while the others were mostly among white or wealthier groups.
“The bottom line is peanuts may be able to serve as an alternative for nuts in cardiovascular health,” said Shu, associate director for Global Health at the Vanderbilt-Ingram Cancer Center and professor of medicine in the Division of Epidemiology. “Particularly for people who cannot afford to incorporate tree nuts.”
Peanuts are legumes, not nuts, because they grow in bushes.
Participants included more than 70,000 Americans of African and European descent from the Southern Community Cohort Study, who were mostly low-income and more than 130,000 Chinese from the Shanghai Women’s Health Study and the Shanghai Men’s Health Study.
Peanut consumption was associated with a 17 percent to 21 percent reduction in deaths and a 23 percent to 38 percent decrease in cardiovascular death, across all three racial and ethnic groups, among both genders and among people with low socioeconomic status.
The study measured the estimated nut/peanut intake level during the last year before investigators began tracking survival status for participants and found that the most beneficial amounts for the U.S. population was about 18 grams or 2/3 ounce of nuts and peanuts a day. That’s a small handful.
Interestingly, Shu said, that jibes with the recommendation from the American Heart Association.
Lifestyle guidelines from the AHA and American College of Cardiology specifically include nuts as part of a dietary pattern that is associated with reduced atherosclerotic risk.
The next step, according to Shu, is to continue to follow the three study groups and look into whether there are any biomarkers in the populations that help to measure the nut/peanut intake more accurately, and to investigate nut/peanut intake in association with mortality from other causes, such as specific types of cancer. She said these studies have collected urine and blood samples and will be able to dig deeper into why the nut consumption helps, such as by comparing metabolic profiles of those who eat more peanuts to those eat less within each of the study groups.
“We hope someone will pick up this idea and do a clinical trial to draw some more conclusions,” Shu said.
Nuts and seeds are typically rich in unsaturated fats, magnesium, and copper, with smaller amounts of protein, fiber, and iron. Still here are few points to remember about nut intake:
- Salt. Each 1-ounce serving, about ¼ cup or 4 flat tablespoons, of salted nuts can have as much as 100 to 300 mg of sodium. So it’s important to check the nutrition facts for sodium and look for unsalted, raw or lightly salted brands.
- Portion control. The latest cohort study showed benefits from nut intake for people who ate 2/3 ounce, or about 18 grams, of peanuts a day, on average. That’s about a handful, with about 28 peanuts per ounce.