Molecules released from digested fibre in the gut suppress appetite by acting on an area of the brain known to regulate hunger, reports a mouse study published in Nature Communications this week. The finding adds to our understanding why a diet rich in fibre is ‘healthy’.
Most processed Western foods are rich in refined sugars and fat but contain little fermentable fibre. Previous animal studies have demonstrated that fermentation of fibre by microbes in the gut reduces overall food intake and body weight and this effect has so far been attributed to the release of appetite-suppressing gut hormones. Gary Frost and colleagues now show that fibre fermentation also has a direct appetite-suppressing effect on the brain. They show that the short-chain fatty acid acetate, which is released from fibre as a result of microbial fermentation in the gut, accumulates and is converted in nerve cells in the hypothalamus of a mouse brain - an area known to regulate hunger. They note that administration of either fibre or pure acetate to mice acutely reduces food intake and induces a pattern of neuronal activity in the brain that is consistent with appetite suppression.
If confirmed in humans, the finding suggests that an increased intake of fermentable dietary fibre may be a feasible strategy for effective weight management.