Reddit AMA: How does the gut microbiome relate to healthy aging?

Drs. Greg Gloor, Gregor Reid, Jeremy Burton and Jean Macklaim participated in a Science AMA (Ask Me Anything) Series following the publication of their “The Gut Microbiota of Healthy Aged Chinese Is Similar to That of the Healthy Young” study.

Their study, one of the largest microbiota studies conducted in humans, has shown a potential link between healthy aging and a healthy gut.

During the AMA, the team of researchers answered over 30 questions relating to the study as well as other questions relating to probiotics and the human microbiome. Diet, environment, and fecal transplants were some of the topics reddit users wanted to discuss.

Each of the researchers also weighed in on the medical breakthroughs in microbiome and probiotic research in the future:

Dr. Greg Gloor: My prediction is that we will begin to understand the inter-relationships between the microbiota and the host. Right now the microbiome community and the human genetic community are not well connected. For example, the particular strains from a single donor that engraft following a fecal transplant differ between different recipients. We don’t understand how or why this happens, but the that the host genetic makeup and immunological response affects engraftment is an obvious starting point. We really can’t start to think about true precision medicine until we understand all the moving parts in play, we can’t just look at the host genetics, nor can we look only at the microbiota, or the broader environment - we need to synthesize all this information in order to truly deliver person-specific advice.

Dr. Gregor Reid: Sample a person’s microbiota and metabolomic read-out, know what drugs they are taking and what toxins they are being exposed to (mercury, pesticides, aflatoxins etc) and ‘design’ a probiotic that gets closer to being ‘personalized’ for whatever purpose is believed to be important to improve their health status. That would require having many probiotic strains available as options, and foods that could promote their influence in the host. Another challenge will be ethically doing this in early life; and another is to apply the intervention to impact distant sites like the brain. Furthermore, we need to know to what extent the intervention helps the person. For example, probiotics can reduce cholesterol, and this might reduce by 12.5% the risk of a cardiac event in the next ten years, while statins may reduce the risk by 25%. Depending on the actual risk of disease, the probiotic approach may not be sufficient. So, we should not promote something that endangers the life of the recipient in any way. Having said that, the side effects of high statin levels are extremely concerning, and we need to be looking at alternatives. If probiotics could reduce the need for high levels of statins, that might be a win-win.

Dr. Jeremy Burton: The gut microbiome composition has been shown to be predictive of certain conditions (T2 diabetes, some kidney stones etc), so the hospital of the future will likely analyse your microbiome, as well as your own genetics. Once a condition has been diagnosed and if there is a microbial link, some kind of microbial therapeutics will be administered in different ways. In a less severe microbial disruption, patients may only receive a dietary intervention, but where a more dramatic shift in the microbiome is required, a faecal transplant may be administered from the hospital “bank” or the person’s own microbiome maybe taken out and put in a gut model to grow and restore their bacterial populations in the laboratory before putting the “restored” microbiome back in the patient as an “auto” transplant.

Dr. Jean Macklaim: One of the things I hope we’ll be better able to understand in the future is how our early exposure to microbes sets the course of our immune response for the rest of our lives. There is a lot of evidence that the bacteria you are exposed to at birth and early in your childhood affects allergies, susceptibility to the common cold, chronic immune disorders, etc. Additionally, it’s very difficult to change your established microbiome and immune function in adulthood. If we are better able to prime our early microbiome, it could affect a lot of these disorders that change the quality of our lives during aging.

More information about the study and the full AMA can be found on Reddit.