Studies have shown the gut microbiome plays an incredibly important role in the health of an individual, having an influence on appetite, energy metabolism, and immune and endocrine functions. The gut microbiome helps with the digestion of food, the creation of essential vitamins, and also trains the innate immune system.
Environmental factors and diet have a major influence on the makeup and health of the gut microbiome, but genetic factors also play a key role. Studies have shown that around 5% to 13% of the microbes that make up the gut microbiome are hereditable, but it would appear that genetics are involved to a much greater extent than previously thought. A much higher percentage of gut microbes have been shown to be hereditable.
A new study shows most of the bacteria present in the gut microbiome are heritable. The researchers studied over 16,000 gut microbiome profiles that were collected over a 14-year period from 585 wild Kenyan baboons. The researchers found gut microbiome hereditability was almost universal but was environmentally contingent. The hereditability of bacteria fluctuated over time and was affected by age and season. When the researchers controlled for diet, age, and socioecological variation, they found 97% of microbiome phenotypes were significantly hereditable, and several microbiome traits identified in the baboons are also heritable in humans.
One of the reasons for the low number of hereditable microbes identified in the gut in previous studies could be due to the snapshot approach when studying the gut microbiome. Studies have been conducted on a sample at a single point in time, when there can be significant variation over time.
The researchers studied the microbiome over a long period of time, with analyses conducted on over 20 fecal samples per animal. The analyses showed significant variation in the makeup of the gut microbiome over time, especially between the wet and dry seasons. In the dry season, hereditability was typically 48% higher. The researchers also studied known descendants, information about environmental conditions, demography, social behavior, and group-level diet at the time each sample was taken. Looking at a single sample, the percentage of microbes that were hereditable fell to just 5%; however, across multiple samples they found 97% of microbiome traits were heritable.
“This really suggests that in human work, part of the reason researchers haven’t found that heritability is because in humans they don’t have a decade and half of fecal samples in the freezer, and they don’t have all the initial host information they need to tease these details out,” said Elizabeth Archie, PhD, professor in the department of biological Sciences at the University of Notre Dame and a principal investigator on the study. “The environment plays a bigger role in shaping the microbiome than your genes, but what this study does is move us away from the idea that genes play very little role in the microbiome to the idea that genes play a pervasive, if small, role.”
The research suggests that with genetics playing an important role in the gut microbiome, it may be possible to develop tailored therapies for patients based on the genetic makeup of their microbiome.
You can read more about the study in the paper – Gut microbiome heritability is nearly universal but environmentally contingent – which was recently published in the Science. DOI: 10.1126/science.aba5483