Ever been told that the little things matter in life? This same proclamation that you’ve been told by your elders rings true in your gut: one small modification to your human gut microbiome (a batch of bacteria that call your digestive tract home) can have drastic effects on your metabolism.

A. Sloan Devlin, assistant professor at Harvard medical school, carried out a study that proved the importance of the gut microbiome. She first located the gene in “an abundant gut bacterium” for an enzyme that processes bile acids. She then removed that gene from the bacterium. Next, she “colonized” “germ-free” mice with one of two types of the gut bacterium: either with the bile-processing enzyme or without the bile-processing enzyme. The results were surprising.

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After both mice were fed the same high-fat, high-sugar diet, the mice without the bile-processing enzyme “had more fat in the liver and gained weight much more slowly than the other group. They also used proportionately less fat and more carbohydrate for energy.” Changing one single enzyme in a gut bacterium appears to change “whether the host is using [primarily] fats versus carbohydrates” for energy.

Even more staggering was the “correlation of lean body mass to energy expenditure.” Typically, in humans and mice, the more lean body mass an organism has, the more energy it expends. However, for the mice without the bile-processing enzyme, this relationship “broke down.” Devlin hypothesizes that this change could be due to a “signaling,” a process in which “physical states in the body trigger a cascade of genes to switch on or off.” Researchers can use this knowledge to treat diseases: figure out which microbiome bacteria activate which genetic switches, and better treatment for genetic problems such as, acid imbalances, metabolic disorders and obesity, may become a reality.

Devlin is sure to stress that this groundbreaking microbiome research is just her “first step.” Although this study was carried out on “germ-free” mice, Devlin dreams that one day she may use her research to improve the health of her own species: as Devlin states, her research brings her “one step closer to humans.”


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