Understanding the Role of Gut Microbes on Eating Behaviour

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When we reach for that extra cookie, slice of pizza, or cake, we’re often under an overwhelming spell: cravings. Still, science is showing that our gut microbes play a key part in this process, influencing our brain.

Our gut microbes work day and night to aid our digestion and deliver nutrients to our organs. However, these microbes can also be responsible for making us miserable, producing toxins if we don’t grant them what they desire. These toxins are often triggered by a low concentration of growth-limiting nutrients and, as a result, these microbes can directly and indirectly manipulate our eating behaviour1. Studies have shown that microbes affect food choices in mice and flies, where germ-free mice changed their food preference once a microbiota was given to them2. In this way, gut microbiomes can interfere with appetite regulation by stimulating the production of auto-antibodies and mimicking satiety-regulating hormones3.

Gut Bacteria Controls Food Appetite

The obesity epidemic and increasing number of eating disorders in people globally suggests there is an insufficiency in our basic understanding of altered appetite. Appetite is fundamental when treating such chronic pathological conditions, therefore, it is crucial to understand how our body generates and regulates it3. Previous research has shown that gut microbial proteins influences the host control of appetite.

Cravings can be reduced by increasing the gut microbiota diversity through probiotics.

The production of peptides in gut bacteria influences food intake as these peptides mimic and interfere with normal appetite regulation. Furthermore, by increasing opioid and cannabinoid receptors and changing our taste buds, the gut microbes can increase appetite. Furthermore, cravings can be reduced by increasing the gut microbiota diversity through probiotics4.

Affect on Hunger and Satiety 

Our feelings of hunger are coordinated with the diversity of our microbiota. A decline in the size of microbiota diversity is associated with hunger, whereas satiety is a reverse process. When feel satiated when we digest nutrients and the anorexigenic pathways in our brain are activated by the intestinal satiety hormones that are released in the stomach5. We often seen a growth in microbes that are responsible for altering the feeling of hunger or satiety in us. For instance, the secretion of hormones such as cholecystokinin regulates the feeling of satiety and hunger when receptors are activated, by binding with bacterial products such as lipopolysaccharides and flagellin 6.

Microbes and Food Preference

Gut bacteria can grow on a variety of substrates, however, different bacteria prefer different dietary substrates depending on the amount of energy they can preserve. Bacteroidetes prefer certain types of fats whereas Bifidobacteria can only surpass other microbes in the presence of dietary fiber. Carbohydrates are the best source for Prevotella to grow, and also Akkermansia muciniphila thrive on carbohydrates secreted by the host cell, without depending on other dietary substrates. This means that low concentration of any of these nutrients can trigger increased virulence toxins in microbes that can cause damage to the host. These toxins can be altered by sugars and other nutrients7.

Therefore, when you crave for chocolate cake, pizza, or junk food, you can blame it on your gut bacteria. However, it is up to you to create a healthier microbiome environment and increase microbiota diversity by adding variety to your diet, eating more fiber and embracing a regular exercise routine.

References

  1. Zubcevic, J. and Martyniuk, C., 2017. Tiny Gut Organisms May Influence Food Cravings And What Our Bodies Do With Fat. [online] Available at: <https://www.washingtonpost.com/national/health-science/tiny-gut-organisms-may-influence-food-cravings-and-what-our-bodies-do-with-fatlooking-at-microbiota-for-ways-to-keep-weight-down–and-fight-depression/2017/08/11/676a1138-6681-11e7-a1d7-9a32c91c6f40_story.html> [Accessed 16 September 2020].
  2. Anderson, S., 2019. The Shocking Source Of Your Cravings. [online] Psychology Today. Available at: <https://www.psychologytoday.com/us/blog/mood-microbe/201905/the-shocking-source-your-cravings> [Accessed 16 September 2020].
  3. Alcock, J., Maley, C.C. and Aktipis, C.A., 2014. Is eating behavior manipulated by the gastrointestinal microbiota? Evolutionary pressures and potential mechanisms. Bioessays, 36(10), pp.940-949.
  4. Fetissov, S.O., 2017. Role of the gut microbiota in host appetite control: bacterial growth to animal feeding behaviour. Nature Reviews Endocrinology, 13(1), p.11.
  5. Lam, Y.Y., Maguire, S., Palacios, T. and Caterson, I.D., 2017. Are the gut bacteria telling us to eat or not to eat? Reviewing the role of gut microbiota in the etiology, disease progression and treatment of eating disorders. Nutrients, 9(6), p.602.
  6. Sun, L.J., Li, J.N. and Nie, Y.Z., 2020. Gut hormones in microbiota-gut-brain cross-talk. Chinese Medical Journal, 133(7), p.826.
  7. Kresser, C., 2019. Do Gut Microbes Control Your Food Cravings?[online] Chris Kresser. Available here. [Accessed 16 September 2020].