Daily dose of nuts improves memory
Healthy eating is not only good for the body, but also for the brain. Research by Kevin Nijssen shows that elderly people who eat two handfuls of nuts every day had better memory and brain perfusion after four months than during a period when they did not eat any additional nuts.
Insulin sensitivity also improved in brain areas potentially involved in cognitive and metabolic processes, and risk factors for cardiovascular disease improved. A daily serving of mixed nuts may therefore help prevent age-related diseases and cognitive decline. On 25 January, Nijssen received his PhD on this study, supervised by Prof Ronald Mensink, Prof Jogchum Plat and Dr. Peter Joris.
In old age, the risk of diabetes and cardiovascular disease increases, and memory and concentration deteriorate. Healthy eating can help you age more healthily. While previous studies have already shown that eating nuts is beneficial in reducing the risk of cardiovascular disease, it was less known whether people who add nuts to a healthy diet benefit in their cognitive functioning. Kevin Nijssen therefore investigated whether eating a nut mix daily has an effect on the brain, and how exactly that works.
Nijssen is a PhD candidate within the Department of Nutrition and Exercise Science at research institute NUTRIM (Institute of Nutrition and Translational Research in Metabolism). His findings were recently published in the scientific journals The American Journal of Clinical Nutrition and Clinical Nutrition.
Over a four-month period, the 28 participants, all between 60 and 70 years old and overweight or obese, ate 60 grams of unsalted nuts every day in equal amounts of pistachios, cashews, hazelnuts and walnuts. Furthermore, they followed the guidelines for a healthy diet. After four months, they scored better on a number of memory tests and their brains were imaged using MRI techniques.
"Our results show that eating nuts for four months is sufficient to get demonstrable improvements in memory," Nijssen explains. "Moreover, we saw increased blood flow in three different areas of the brain. That more blood goes to the brain areas involved in cognitive functions may account for the improvement in memory we observed." The findings of this study provide further evidence that regular nut consumption can help prevent cognitive decline in ageing.
Nijssen is the first to study the effect of a nutritional intervention, eating extra nuts, on insulin sensitivity in different brain regions. Insulin is best known as a hormone that allows the body to absorb glucose into the cells of, for example, the muscles or the liver. In the brain, however, insulin has a very different action. For example, insulin in the brain is involved in cognitive function, among other things, but also inhibits the feeling of hunger.
"Our previous research shows that the function of insulin in the brain changes as we get older, but also in overweight, obese or type 2 diabetic adults. We have now been able to show that eating nuts can actually improve the insulin sensitivity of certain brain regions in overweight or obese older adults." Nijssen recently received the Kootstra Talent Fellowship from Maastricht UMC+ to further study the brain's response to insulin.
Nuts not only have beneficial effects on the brain, but other results within the study also point to the health benefits of consuming nuts. Participants in the nut study had reduced blood pressure, reduced cholesterol levels and improved blood vessel function. These are all risk factors for cardiovascular disease. Therefore, a daily dose of mixed nuts, combined with a healthy diet, can help prevent age-related diseases and cognitive decline.