If the nutritional values were the same, could different foods have different impacts on health?

The Pima of Arizona were among the first communities to be examined with a genome-wide survey. Many candidate genes were shown to be associated with obesity, but weakly so. The conclusion was that there are genetic contributions to the propensity to develop obesity, but except for a few rare cases, obesity is a multigenic trait that is highly influenced by environment. One aspect of the environment is physical activity, but another one is diet. The caloric content of the diet is obviously an important factor, but what about the composition of the diet? The experiments described in Investigating Life: How Does the Gut Microbiome Contribute to Obesity and Metabolic Disease? show that the composition of the diet can influence the composition of the gut microbiome, and the gut microbiome can influence the nutritional and other health effects of the diet. Thus, apart from differences in caloric intake, the consequences of the Pima switching from a traditional diet to a high-fat Western diet could have resulted in changes in their microbiomes that have contributed to obesity and diabetes.

Future directions

It would be of interest to compare the microbiomes of the Arizona and the Mexican Pima peoples, and to compare those with the microbiomes of other populations on similar and different diets. If a particular microbiome profile is associated with the obesity–diabetes phenotype, it might be possible to change that microbiome through dietary change to promote better health. Just as we now do genomic screening to identify health risks, we might consider microbiome screening. Whereas we cannot change our genetic makeup, we could change our microbiome either through diet, or even therapeutically by uses of antibiotics and microbiome transplants. A new branch of medicine could develop around the testing, diagnosis, and therapy of the gut microbiome.