Some really cool new papers are out on the human microbiome today. But alas that is not what I am here to talk about. I am here, once again, to complain about overselling the microbome. There is a headline from a press release from one of the institutes involved in one of the new studies that really irks me: "
Intestinal flora determines health of obese people". As far as I can tell from reading the paper under discussion in this PR, nothing showed that the flora "determined" the health of obese people. Yes, the flora had really interesting correlations with health status. But "determines health" implies that the flora were the causal component of the health of obese people. And as far as I can tell this was not shown. What was shown was that the microbial communities - and some metrics of those communities like richness - can help predict risk of individuals for various health related ailments.
Now, mind you, the person discussed in this PR Jeroen Raes is completely brilliant and one of my favorite people in science in many ways. And also it is important to point out that the paper does not make these claims. The paper says things like
Our classifications based on variation in the gut microbiome identify subsets of individuals in the general white adult population who may be at increased risk of progressing to adiposity-associated co-morbidities
