Less age-related brain inflammation with regular dietary fiber intake, says this University of Illinois study adds a new health benefit of these nutrients. Here, it is precisely on immune cells in the brain known as microglia that the fibers exert their effects, thus helping to reduce age-related cognitive decline. Benefits documented in the journal Frontiers in Immunology mainly linked to their by-products, short-chain fatty acids including butyrate.
With age, microglia in the brain produce chemicals known to impair cognitive and motor function. It is one of the explanations and causes of the decline of memory and other brain functions in the elderly. This study from the University of Illinois offers a simple and natural remedy, dietary fiber . We knew that they promote the growth of good bacteria in the intestine. When these bacteria digest fiber, they produce short-chain fatty acids (SCFAs), including butyrate.
Understanding how sodium butyrate works: Butyrate has anti-inflammatory properties on microglia and improves memory in mice, previous studies have shown, says Dr. Rodney Johnson, a professor at the University of Illinois. Although positive results of sodium butyrate – the pharmacological form – have been observed in these studies, the mechanism of action remains poorly understood. The study reveals, in aged mice, that butyrate inhibits the production of harmful chemicals by inflamed microglia. One such chemical is interleukin-1β, which is associated with Alzheimer's disease in humans. This being demonstrated, humans cannot directly consume sodium butyrate, so there remains the solution of a diet rich in soluble fiber.
Gut bacteria convert fiber to butyrate naturally . Indeed, butyrate derived from dietary fiber should have the same benefits in the brain as the drug form, yet no one had tested it before. So the researchers fed groups of young and old mice low-fiber and high-fiber diets, then measured blood levels of butyrate and other SCFAs, as well as inflammatory chemicals in the blood. 'intestine. This experience shows that:
- a high-fiber diet increases butyrate and other SCFAs in the blood, both in young and older mice;
- only old mice show intestinal inflammation with a low-fiber diet;
- older mice fed a high-fiber diet had significantly reduced gut inflammation and no gut differences with other age groups. This confirms that dietary fiber can indeed regulate the inflammatory environment in the gut;
- examination of signs of inflammation in the brain via the analysis of 50 unique genes in microglia finally shows that the high fiber diet reduces the inflammatory profile in aged animals.
The next step will be to examine the effects of diets on cognition and behavior or the precise mechanisms of the gut-brain axis. And if these data were obtained in mice, the researchers are confident about their generalization to humans.
“ What you eat matters. We know that older people consume 40% less dietary fiber than recommended. Not getting enough fiber could have negative consequences for brain health and inflammation in general .”