Youth adherence to the Western diet, which includes consumption of less than five food groups per day and high consumption of grains, milk products, and meat, has been linked to poor cognitive function. Adherence to nutrient-dense diets, however, such as the Mediterranean diet, has been linked to improved cognitive performance in youth.
How exactly diet affects cognitive function is not fully understood. Increasing evidence, however, points towards gut-brain axis involvement, with diet accounting for up to 57% of gut microbiota variability.
In the current study, researchers investigated the effects of Mediterranean and Western diets on fecal microbiota composition, cognitive function, and physiological outcomes.
To do so, they assigned ten-week-old male rats either a Mediterranean or Western diet for 14 weeks. The researchers collected fecal samples from the rats at baseline and at week 14. Neurobehavioral tests, including maze challenges to assess memory and learning, were also carried out after the dieting period, and blood samples were drawn to assess cholesterol and cytokine levels.
Ultimately, rats on onthe Mediterranean diet experienced an increased relative abundance of four beneficial types of gut bacteria and a decreased abundance of five others compared to counterparts on the Western diet. The bacterial changes were linked to better performance on neurobehavioral tests.
Rats in the Mediterranean diet group also demonstrated better cognitive flexibility and working memory compared to those in the Western Diet group. They also experienced lower LDL cholesterol levels and higher levels of serum cytokines. Markers for neuroinflammation, blood-brain barrier, glial cells, and synaptic plasticity were similar between the groups.
The researchers concluded that more research is needed to better understand the link between diet-modulated gut microbiota, cognitive function, and immune function.
Sources: EurekAlert, Gut Microbes Reports
