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Does Dietary Fibre Act On Your Brain?



sharma-obesity-brainThe notion that adding fibre to your diet may promote satiety and reduce hunger has been around for a long time and there is some evidence that (at least some) fibres do just that.

However, I have often thought of this as a gut effect – perhaps volume increases, slowing gastric emptying or some other “local” impact on the GI system.

Now, a much publicized study by Gary Frost and colleagues, published in Nature Communications, suggests that it may well be due to a direct impact of a fibre metabolite on the appetite regulating centres of the brain – at least in mice.

In their study, the researchers fed mice a high-fat (HF) diet supplemented either with inulin (I) or cellulose (C) – both are fibres, but whereas inulin is readily fermented by the bacteria in our gut, cellulose is not.

After 8 weeks, mice fed the HF-I diet consumed significantly less food and gained less weight than those fed HF-C.

Using isotope labelling, the researchers demonstrated that the acetate produced in the gut as a result of fermentation of the inulin crosses the blood–brain barrier and is taken up by the brain.

They also showed that simply injecting acetate into the peritoneum results in appetite suppression and hypothalamic neuronal activation patterning.

Finally, they dilineated a pathway how acetate may affect neurotransmitters in the hypothalamus that mediate hunger and satiety.

From these findings, the researchers conclude that acetate (as derived from increased fibre intake) has a direct role in central appetite regulation.

As acetate is produced through the fermentation process in the gut, which in turn requires the right spectrum of gut bacteria, these findings also provide more support for the notion that our gut bugs can have a direct impact on appetite.

@DrSharma
Toronto, AB

ResearchBlogging.orgFrost G, Sleeth ML, Sahuri-Arisoylu M, Lizarbe B, Cerdan S, Brody L, Anastasovska J, Ghourab S, Hankir M, Zhang S, Carling D, Swann JR, Gibson G, Viardot A, Morrison D, Louise Thomas E, & Bell JD (2014). The short-chain fatty acid acetate reduces appetite via a central homeostatic mechanism. Nature communications, 5 PMID: 24781306

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1 Comment

  1. I value this site for flagging significant research, as well as the commentary that usually accompanies the notification, and not in the least, your exceedingly well informed rumination and speculation.

    I wonder in this instance whether the use of vinegar in advance of a meal might serve some of the same function as fiber. I suppose the key is whether acetic acid itself can make it through the gut to ultimately produce acetate in the intestine.

    Another interesting thing to ponder is the division of the energy contained in food between “us” and our microbiome. Maybe some of us do have a tape worm, metaphorically speaking. The life within us — well okay, the symbiotic life with us, at least — must be fed.

    That poses the question of what is the right spectrum and how does it vary among “us.”

    Not only for appetite control, I might say, but for optimum functioning of our self, which comprises all the life within us.

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