The topic of the gut microbiota is increasingly in the news of late, and its connection with chronic age-related inflammation, known as inflammaging, is becoming increasingly clear.
What is the microbiota?
The microbiota describes the community of symbiotic and pathogenic microorganisms that live in and on all multicellular organisms, and it includes bacteria, archaea, protists, fungi, and viruses. In particular, the gut microbiota and its role in aging and disease have increasingly become of interest to researchers in recent years.
As we age, the microbiota increasingly favors pro-inflammatory activity, as a lifetime of exposure to pathogens changes the delicate balance from pro-youthful to pro-aging. The inflammation this generates contributes to the chronic, low-grade background of age-related inflammation known as ‘inflammaging’ as well as from other sources, such as senescent cells, cell debris, and crosslinks.
A healthy gut impacts health as we age
Researchers have recently conducted one of the largest studies of the microbiota in humans to date at the Western University, Lawson Health Research Institute in Canada and the Tianyi Health Science Institute in Zhenjiang, Jiangsu, China. The study shows a potential link between a healthy gut microbiota and the impact it has on aging.
The researchers studied the gut microbiota in over 1,000 Chinese people with ages from 3 to over 100 years old. The people were healthy with no known health issues and no family history of disease. The results of the study showed a direct correlation between health and gut microbiota.
The researchers are aiming to bring microbiota diagnostic systems to people, then use food and probiotics to attempt to improve health based on those diagnostics. The question they wish to answer is: if you can stay active and eat well, will you age better, or is healthy aging predicted by the bacteria in your gut?
The study showed that the general microbiota composition in the healthy elderly group was similar to the microbiota in people decades younger, and there was little variation between individuals aged between 30 and 100 plus. This means that the gut microbiota is not really that much different in a very healthy 90 year old compared to a healthy 30-year-old in the same population.
It is unclear if this is a cause or effect, but the study shows that gut microbiota diversity was a common trait among very healthy people of all ages. This suggests that maintaining the diversity of the gut microbiota as you age is a potential biomarker for health, just like low cholesterol and optimal blood pressure are. The researchers believe that resetting the microbiota in elderly people to that of healthy 30-year-olds could potentially help to improve their health.
This study could show us what the ideal balance in the gut microbiota is and what we should be aiming for when attempting to reset the microbiota. The better we understand the types of microbes and their ratios in the microbiota, the better we can emulate this in everyone to help promote health.
The microbiota is increasingly being implicated for its contribution to age-related inflammation[3-4] with some studies going as far as to suggest it may be the origin point for inflammaging. The hierarchy of inflammation sources that collectively make up inflammaging is not yet established, but it is plausible that the microbiota favoring a pro-inflammatory profile as we age may potentially be the first spark that ignites the fire.
If this is the case then finding ways to restore the microbiota to a more healthy composition could be a possible way to promote health. If we can optimize the microbiota, we could potentially reduce that chronic inflammation and thus impact health and how we age.
 López-Otín, C., Blasco, M. A., Partridge, L., Serrano, M., & Kroemer, G. (2013). The hallmarks of aging. Cell, 153(6), 1194-1217.
 Bian, G., Gloor, G. B., Gong, A., Jia, C., Zhang, W., Hu, J., … & Burton, J. P. (2017). The Gut Microbiota of Healthy Aged Chinese Is Similar to That of the Healthy Young. mSphere, 2(5), e00327-17.
 Buford, T. W. (2017). (Dis) Trust your gut: the gut microbiome in age-related inflammation, health, and disease. Microbiome, 5(1), 80.
 Levy, M., Kolodziejczyk, A. A., Thaiss, C. A., & Elinav, E. (2017). Dysbiosis and the immune system. Nature Reviews Immunology, 17(4), 219-232.
 Thevaranjan, N., Puchta, A., Schulz, C., Naidoo, A., Szamosi, J. C., Verschoor, C. P., … & Schertzer, J. D. (2017). Age-Associated Microbial Dysbiosis Promotes Intestinal Permeability, Systemic Inflammation, and Macrophage Dysfunction. Cell Host & Microbe, 21(4), 455-466.