Environment is the Biggest Factor Shaping the Microbiome
Environment is more important than genetics in shaping the microbiome, according to a new study in the journal Nature. In addition, including microbiome characteristics when predicting peoples traits, such as obesity or cholesterol levels, makes those predictions much more accurate than using personal history alone.
The relative contributions of diet and genetics to microbiome composition have been the subject of much scientific debate.
To address the question of which is more important (genetics or environment), scientists from the Weizmann Institute collected blood and stool samples from 1,046 Israeli adults of various genetic backgrounds, including Ashkenazi, North African, Yemenite, Sephardi, and Middle Eastern descent.
They compared the genetics profiles and microbiome diversity between the samples and found no association between ancestry and microbiome composition.
Next, they analyzed data from a 2016 study of microbiome composition from 1,126 pairs of twins to see whether the human gut microbiome can be inherited. They found that only 2-8% of the microbiome is heritable.
So, two different sets of data (with large sample sizes) confirm that genetics makes a very small contribution to microbiome composition.
To understand the amount of environmental influence, the researchers looked at the microbiomes of relatives who had never lived together, and unrelated couples who live together. The microbiomes of relatives living apart were not alike; however, the microbiomes of cohabiting unrelated couples were very similar.
Finally, the research team examined what fraction of human health characteristics (cholesterol levels, BMI) could be inferred from microbiome composition. They found that combining genetic data and microbiome profiles greatly improved how accurately they could predict these characteristics.
This is great news. It means that the microbiome can be altered by diet and that such alterations should be widely applicable across different genetic backgrounds.