To test how eating walnuts affects brain function, researchers randomly selected 64 college students to follow their regular diet or their regular diet plus walnuts for 16 weeks. For 8 of the 16 weeks, half the group ate three slices of banana bread providing ½ cup walnuts per day, and the other half ate banana bread without walnuts.
All participants then ate their regular diet without walnuts for six weeks (called a washout period). The walnut and no-walnut groups were switched for the last eight weeks, so that everyone had an eight-week period of eating walnuts and an eight-week period of not eating walnuts.
Nonverbal reasoning, verbal reasoning, memory, and mood tests were conducted at the study’s initiation, after eight weeks of intervention, and again after the second eight weeks of walnut and no-walnut diets.
Inferential reasoning (the ability to draw accurate conclusions from a group of facts) was tested by reading the students a short narrative followed by five statements, after which they had to decide whether the statements were true, partially true, false, partially false, or whether there was not enough information to make a judgment.
After analyzing the test results, the researchers noted an 11.2% increase in the ability to perform inferential reasoning among the students when they were on the walnut-supplemented diet compared with the no-walnut diet. They detected no significant increases in mood, non-verbal reasoning, or memory.
This study suggests that in young, healthy adults, walnuts may improve inferential reasoning. One study doesn’t prove walnuts are going to improve your brain function, but there aren’t many downsides to adding them into your healthy eating plan. Our tips and hints will help you get more walnuts into your diet.
(Br J Nutr 20011, doi: 10.1017/S0007114511004302)
Suzanne Dixon, MPH, MS, RD, an author, speaker, and internationally recognized expert in chronic disease prevention, epidemiology, and nutrition, has taught medical, nursing, public health, and alternative medicine coursework. She has delivered over 150 invited lectures to health professionals and consumers and is the creator of a nutrition website acclaimed by the New York Times and Time magazine. Suzanne received her training in epidemiology and nutrition at the University of Michigan, School of Public Health at Ann Arbor.