Eating mixed nuts for 16 weeks could improve insulin sensitivity in the brain, study suggests

A recent study of overweight or obese older adults found that daily consumption of 60 grams of a mixture of nuts, pistachios, cashews and hazelnuts for 16 weeks improved insulin sensitivity in five distinct regions of the brain. However, there were no significant changes in body weight, body composition, or peripheral insulin sensitivity. The research was published in the American Journal of Clinical Nutrition.

Insulin is a hormone produced by the pancreas that regulates blood sugar levels by facilitating the uptake of glucose into cells for energy production and storage. It helps the body’s cells absorb glucose from the bloodstream to use as an energy source or store it as glycogen in the liver and muscle tissues. When blood sugar levels rise, such as after eating, the pancreas releases insulin to help maintain a balanced, healthy sugar level.

Dysfunction in insulin production or activity can lead to metabolic disorders such as diabetes, characterized by insufficient insulin production or inefficient use of insulin by the body. This dysfunction also extends to brain cells, known as brain insulin resistance, which can impair neural cell function and contribute to various neurological and mental health disorders, including Alzheimer’s disease, where it is associated with cognitive decline.

Study author Kevin MR Nijssen and colleagues wanted to determine whether a diet including various nuts would improve brain insulin sensitivity in overweight or obese older adults. They pointed out that nuts are nutrient-dense foods, abundant in unsaturated fats and other bioactive compounds. Previous studies have shown that incorporating nuts into the diet reduces the risk of developing metabolic and cognitive disorders. The researchers designed an experiment to test this hypothesis.

The study included 28 participants aged 60 to 70, half of whom were women, all of whom were overweight or obese. The participants were divided into two groups. One group began by consuming 60 grams of unsalted, unroasted mixed nuts daily for 16 weeks, followed by an 8-week break, and then another 16 weeks without nut consumption. The second group followed the reverse order.

Researchers collected blood samples from participants at the beginning, middle, and end of the intervention period to measure peripheral insulin sensitivity, lipid profiles, systemic inflammation, and neurotrophic factor levels. brain-derived (a protein essential for the survival and growth of neurons). . Additionally, participants underwent magnetic resonance imaging and had their blood pressure measured throughout the study.

Results indicated no changes in participants’ weight or body composition throughout the study. However, during the nut-eating phase, participants reduced their carbohydrate intake and slightly increased their fat intake.

Brain imaging analysis identified five groups of brain cells with increased sensitivity to insulin, located in the left and right occipital lobes and one group in the left frontal lobe. Peripheral insulin sensitivity remained unchanged.

The authors concluded: “Longer-term daily consumption of mixed nuts for 16 weeks improved brain insulin action in occipital and frontal regions. Therefore, regional brain insulin resistance observed in older adults with overweight or obesity may be beneficially affected by intervention strategies, which may be important for the prevention of age-related metabolic diseases. .

The study highlights the potential impacts of diet on insulin resistance in the brains of overweight or obese older adults. However, it is important to note the small number of participants and the fact that the improvement in insulin sensitivity was limited to specific regions of the brain. Additionally, the study design does not clarify whether the observed effects were solely due to nut consumption or whether they resulted from a reduction in other dietary intakes when nuts were included in the diet daily.

The article titled “Consumption of mixed nuts improves brain insulin sensitivity: a randomized, single-blind, controlled crossover trial in overweight or obese older adults” was written by Kevin MR Nijssen, Ronald P Mensink , Jogchum Plat, Dimo ​​Ivanov, Hubert. Preissl and Peter J Joris.