Microbiologists have known diets have the power to change the colonies of bacteria that reside within our stomachs, but what they weren’t sure of was how our genes played a part. With our metabolism, appetite, and risk for obesity depending upon the millions of bacteria within our bellies, the importance of investigation has become paramount in an obese America. A team of microbiologists at Cornell University studied the gut microbiomes of over a thousand pairs of twins with the hope of understanding how each person’s own personal batch of gut bacteria is inherited and influenced.

“Diet is known to be an important factor that determines our gut microbiomes — we are what we eat!” the study’s co-author Emily Davenport, a postdoctoral researcher at Cornell University’s Department of Molecular Biology and Genetics, explained to Medical Daily. “The bacteria in the gut help us digest food that we otherwise would not be able to. Many of the microbiomes are clearly related to diet.”

For the study, published in the journal Cell Host & Microbe, researchers analyzed data collected from 1,126 pairs of twins who were part of the TwinsUK Study, which is a multi-year body of research aimed at studying a variety of diseases and conditions. Researchers zeroed in on the gut microbiome data from both fraternal and paternal twins in order to figure out which genes were influenced by the environment and which were inherited hand-me-down genes. The data, which was collected from fecal samples of the participants, allowed the researchers to search through their genomes for similarities between each twin pair.

"We set out to find out about human genes that are implicated in the regulation of the gut microbiome, and we found some that are," said the study’s senior author Ruth Ley, a professor in Cornell University’s Microbiology Department, in a statement. "Based on our research, we identified more than a dozen microbes with known links to health that are heritable. These microorganisms are environmentally acquired, but the genome also plays a part--by determining which microorganisms are more dominant than others."

One heritable connection the researchers were most confident about was between a type of microorganism in the gut called Bifidobacterium and the LCT gene, which is responsible for making an enzyme that helps the body digest dairy. They found twins with the LCT gene also had Bifidobacterium within their guts, which is commonly used in probiotics for its ability to reinforce the immune system and ease digestion. Davenport says although they’ve discovered the link, her and fellow researchers want to explore more.

“There are many open questions to address,” Davenport explained. “Are there particular bacterial functions that are heritable rather than individual groups? What is the mechanism by which Bifidobacterial abundance differs between lactose tolerant and intolerant individuals? Will similar associations be seen in additional populations around the globe, where environmental exposures differ, such as diet, access to medical care, and climate?”

The research team plans to continue revealing more links between heritable genomes, and according to Ley, they have plenty of uncharted territory to explore. "This type of study opens up many questions but doesn't give us a lot of answers yet. It gives us lots of ideas to study."

Source: Ley RE, Goodrich JK, and Davenport ER, et al. Genetic Determinants of the Gut Microbiome in UK Twins. Cell Host & Microbe . 2016.