The human body is crawling with life. So much so, that the bacteria on and in our bodies outnumber our own cells 10 to one. Yet only recently have researchers discovered just how much influence these microorganisms have over our bodies and health. A growing body of evidence suggests that our gut bacteria plays a significant role in obesity, with a new study once again highlighting this link and the fact that the bacteria is heritable.
The study, published in the journal Genome Biology, used data extracted from the stool samples of 1,313 twins, provided through the TwinsUK cohort, which is a long-term project that has been using twins to assess the genetics behind many diseases. Coupling the twins' stool data with six measures of obesity, including their BMI and upper and lower body fat ratios, the researchers were able to find a link between the bacteria diversity in the twins' feces and their visceral fat levels.
This association was then backed up further, as the researchers used two more population-based cohorts to confirm their findings. The results are interesting because visceral fat – the lipid that surrounds many major organs such as the liver, pancreas, and intestines – is linked to a higher risk of cardiovascular disease and diabetes. The researchers found that twins with the highest diversity of bacteria in their poop also had the lowest levels of visceral fat, and vice versa.
“This study has shown a clear link between bacterial diversity in feces and markers of obesity and cardiovascular risk, particularly for visceral fat,” said Dr Michelle Beaumont of King’s College London in a statement. “However, as this was an observational study we cannot say precisely how communities of bacteria in the gut might influence the storage of fat in the body, or whether a different mechanism is involved in weight gain.”
One theory to explain the connection they found is the idea that a gut microbiome with low diversity allows certain classes of bacteria to dominate, such as those that are more efficient at turning carbohydrates into fat. When the diversity of microbes increases, it could suppress these other groups. Either way, more research is underway to try and unravel exactly what is going on.
This latest research was conducted using data collected for the TwinsUK project. Originally set up to investigate the rate of osteoporosis and rheumatologic diseases in twins, the cohort now includes a total of 12,000 monozygotic (identical) and dizygotic (non-identical) twins, and has been expanded to look at the genetics behind a wide variety of conditions. So far, studies have found genes associated with over 30 different diseases, including melanoma, baldness, and osteoarthritis.