4. Feeding bacteria

A person whose microbiome is lacking in diversity can improve its wealth through their diet. A diet rich in fruit, vegetables and whole foods, many different sources of fiber, seems to be the healthiest option for us and our bacteria. However, as Professor of Genetics at the University of Valencia Andrés Moya pointed out, we don’t yet know the level of diversity that correlates with health, “and if we aren’t yet sure what a healthy microbiome is, it’s more difficult to know what is unhealthy.”


How can we change our bacteria? Prebiotics, probiotics and fecal transplants

Although genetics does seem to have an effect on our microbiome, there are several ways to change and improve the bacteria we co-exist with. One of these is through our diet: eating different sources of fiber, mainly from fruit, vegetables and whole grains, is associated with a richer, healthier microbiome. Another is by taking prebiotics and probiotics. The former are substances, generally sugars, that promote the growth of beneficial bacteria. The second are living microorganisms associated with healthy effects. What is classified as a probiotic and the regulations it must follow is still the subject of much debate, but it is generally accepted that several strains of bacteria have been proven effective, for example, in treating some types of diarrhea. The problem, according to Guarner, is that there are “some 30 useful, well-studied probiotics but pharmacies sell up to 100 others whose efficacy hasn’t been shown.”

The final way to alter the microbiome is through fecal transplants: transferring concentrated feces from one person to another through nasogastric intubation or a colonoscopy. Some studies have found this process helpful in treating persistent diarrhea and even in improving some symptoms of diabetes. But there are drawbacks: they aren’t very specific, most of what is being transplanted is unknown, and the donor and recipient must be compatible, although the markers that could better identify the best matches have yet to be established.