Walnuts have long been linked to better heart health. Research from the David Geffen School of Medicine at UCLA shows these tasty tree nuts may be good for the brain, too.
Study scientists used data from the National Health and Nutrition Examination Survey, which includes a large sampling of the U.S. population, to connect the dots between walnut consumption and better cognition. The March 2015 study, done with partial funding from the California Walnut Commission and published in the Journal of Nutrition, Health and Aging, found that among people over 60, those who ate 13 grams of walnuts (about 6-7 walnut halves) a day performed better on a series of six brain function tests, including tests of memory, concentration and information-processing speed. "We saw an effect in people who ate a handful of walnuts per day," says head researcher Lenore Arab, a professor of epidemiology at the school.
Scientists haven't yet isolated the walnut's key brain-boosting compounds. "There are numerous possible active ingredients, ranging from the high antioxidant content of walnuts or the combination of numerous vitamins and minerals, as well as the fact that they are the only nut that contains a significant source of alpha-linolenic acid (ALA), a plant-based omega-3 fatty acid," says Arab. Omega-3 fatty acids have been shown to lower risk of heart disease and improve cholesterol, while also relieving conditions such as depression and arthritis. "For now, we just know that walnut eaters in the U.S. population perform better on tests of cognitive function than those who don't eat walnuts."
Studies in mice have shown that walnuts may prevent or slow the progression of Alzheimer's disease, a finding that may one day be borne out in people, Arab says. Thus, public health researchers have good reason to promote the nut. Says Arab: "It's not every day that research results in such simple advice — that eating a handful of walnuts a day can help improve your cognitive health."
• “A cross sectional study of the association between walnut consumption and cognitive function among adult U.S. populations represented in NHANES,” The Journal of Nutrition, Health & Aging, March 2015. The purpose of this study was to evaluate the protective effects of eating walnuts on the brain. Participants were asked about their diet, including whether they ate walnuts and how much of these nuts they consumed. The authors used NHANES assessments to evaluate participants’ thinking skills. One weakness of the study is that the authors didn’t randomly assign people to two groups — one that ate walnuts and one that didn’t. They based their findings on people’s recollection of what they ate, which isn’t always precise. Read the full study.
• “Dietary Supplementation of Walnuts Improves Memory Deficits and Learning Skills in Transgenic Mouse Model of Alzheimer’s Disease,” Journal of Alzheimer’s Disease, October 2014. Researchers studied the effects of eating walnuts on learning and memory in mice that were genetically altered to have a condition similar to Alzheimer’s disease. Starting at age 4 months, the mice in the experimental group were fed diets containing either 6 percent or 9 percent walnuts — the equivalent of 1 to 1.5 ounces a day in humans. The control group did not eat walnuts. After nine to 10 months on these diets, the mice that ate walnuts showed a significant improvement in memory and learning ability compared to the mice that didn’t eat walnuts. Read the full study.
