A new study has determined that not only are bacteria naturally found in the gut involved in obesity, diabetes, and cardiovascular disease, but they are genetically inherited. Researchers at King's College London and Cornell University identified a highly-heritable bacterial family that is more common in individuals with low body weight and that could pave the way for genetics-based personalized probiotic therapies for obesity-related diseases.

The study examined 1,081 fecal samples taken from 977 people – 171 pairs of identical twins and 245 pairs of non-identical twins, plus 145 other, individual twins. Microbes from a bacterial family called Christensenellaceae, and to a lesser extent other specific microbe populations, were significantly more similar in the identical twins than non-identical twins, suggesting a strong genetic (and thus hereditary) influence in gut microbe composition.

The study suggests that altering the Christensenellaceae population may have a direct impact on susceptibility to obesity, as mice treated with the microbe gained less weight than untreated mice. The researchers believe that similar personalized microbe treatments in humans could be a promising new aid in the fight against obesity – both in terms of prevention and reduction.

But first they need to expand their research and test the microbiomes of the broader population – not just twins – to better understand the links between genetics, microbes, and weight loss and gain. For this, co-author and King's College London professor Tim Spector urges people living in the UK to sign up to the crowdsourced British Gut Project to have their microbes genetically tested. "We want thousands to join up so we can continue to make major discoveries about the links between our gut and our health," Spector says.

In other studies, gut microbes have also been identified as the key to dark chocolate's health benefits and as being linked to food allergies, and potential probiotic therapies may help both this and obesity.

A paper describing the research into the heredity of gut microbes was published in the journal Cell.