New Publication: Gut Microbiome and Obesity

In collaboration with Katherine Pollard‘s lab at the Gladstone Institutes, we published a paper in PLoS ONE yesterday entitled “A Taxonomic Signature of Obesity in the Microbiome? Getting to the Guts of the Matter.”

We analyzed  the taxonomic diversity of human gut microbiome samples collected from several distinct clinical studies for which each patient’s body-mass index (BMI) was measured. While some independent studies find an association between taxonomic diversity and obesity (as measured by high BMI), we do not observe any taxonomic signature that is consistent across high-BMI patient populations. This suggests that there is no simple signature of obesity in  human gut microbiome structure and that cryptic variables may contribute to the signatures identified in some independent studies. The abstract follows:

Obesity is an important and intractable public health problem. In addition to the well-known risk factors of behavior, diet, and genetics, gut microbial communities were recently identified as another possible source of risk and a potential therapeutic target. However, human and animal-model studies have yielded conflicting results about the precise nature of associations between microbiome composition and obesity. In this paper, we use publicly available data from the Human Microbiome Project (HMP) and MetaHIT, both surveys of healthy adults that include obese individuals, plus two smaller studies that specifically examined lean versus obese adults. We find that inter-study variability in the taxonomic composition of stool microbiomes far exceeds differences between lean and obese individuals within studies. Our analyses further reveal a high degree of variability in stool microbiome composition and diversity across individuals. While we confirm the previously published small, but statistically significant, differences in phylum-level taxonomic composition between lean and obese individuals in several cohorts, we find no association between BMI and taxonomic composition of stool microbiomes in the larger HMP and MetaHIT datasets. We explore a range of different statistical techniques and show that this result is robust to the choice of methodology. Differences between studies are likely due to a combination of technical and clinical factors. We conclude that there is no simple taxonomic signature of obesity in the microbiota of the human gut.