How Do Genetics and Gut Bacteria Affect Weight Gain?

Genetics influence our body make-up and weight by determining which microbe-types flourish in our body independent of environmental factors, according to a recent study.

“If you look across the population [of gut bacteria] and explain abundances, there is a host genetic component,” said Ruth Ley, PhD, senior author of the study and an associate professor of microbiology at Cornell University.
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“Up until now there had been no direct evidence that anything in the human gut is under that kind of [genetic] influence,” she said.

For the study, researchers evaluated genetic data for over 1000 participants, including 171 identical and 245 fraternal twins. The participant’s genomes were sequenced at King’s College in London and were stored in the school’s “TwinsUK” registry.

The researchers were able to rank the heritable microbes in the human gut, and identified the most heritable, a bacterial family known as Christensenellaceae.   They discovered that Christensenellaceae minuta (a member of the bacterial class) was associated with lean body mass index (BMI).

Researchers then added C. minuta to a microbiome environment associated with obesity and inserted the samples into germ-free mice. The C. minuta successfully altered the microbiome of the mice, reducing weight gain.

“Our findings indicate that host genetics influence the composition of the human gut microbiome and can do so in ways that impact host metabolism,” they wrote.

They suggested that their findings should allow for personalized probiotic therapies in patients sometime in the future. Each therapy should reduce the risk of obesity-related diseases in patients based on his or her genetic make-up.

The complete study is published in the November issue of Cell.

-Michelle Canales

Reference:

1. Goodrich JK, Waters JL, Poole AC, Sutter JL, et al. Human genetics shape the gut microbiome. Cell. 2014 November 6 [epub ahead of print] DOI: http://dx.doi.org/10.1016/j.cell.2014.09.053

2. Cornell University. Gut bacteria: how genes determine the fit of your jeans. November 6, 2014. http://mediarelations.cornell.edu/2014/11/06/gut-bacteria-how-genes-determine-the-fit-of-your-jeans/. Accessed November 10, 2014.