As research of the gut microbiota continues, we are learning more about how our gut bacterial balance may affect our health—and we are also learning that there is still a lot that we don’t know! A recent study published in the journal Nature made some good strides towards our understanding of the gut microbiota in the elderly.1 The researchers determined the fecal bacterial composition in 178 elderly people (average age 78). They also looked at dietary intake, and measured a range of physiological and psychological factors and inflammatory markers to find any associations to the gut microbiota.

The participants were separated into four groups based on location: community-dwellers, attendants of an out-patient day hospital, those in short-term rehabilitation hospital care, and those in long-term residential care. They also included 13 young adults, average age 36. What they found was a greater diversity of bacteria in the community-dwelling group when compared to the long-term residential care group. Also, the variation in gut bacteria between individuals was greater in younger adults compared to older adults. So, as we age, gut bacterial diversity decreases overall.

The gut microbiota composition was found to depend on where the individual lived and what he or she ate. Those with the most diverse diet (a high-fiber, low-fat diet) were found to have the most diverse gut bacteria. Those individuals who ate a diet low in fiber and either high or moderate in fat were found to have the least gut diversity. The researchers suggest that diet was the underlying factor that contributed to a change in microbiota that, in turn, contributed to the health of the individual.

“Our findings indicate that any two given older people, independent of starting health status and genetic makeup, could experience very different rates of health loss upon aging due to dietary choices that impact on their gut bacterial ecosystem,” stated Paul O’Toole, lead author. “You can think of [diet] as another controllable environmental factor that we can act upon to promote healthier aging.”

Markers of inflammation (serum TNF-alpha, IL-6, IL-8, and C-reactive protein) were found to be higher in the long-stay and rehabilitation groups than in community dwellers. And loss of the bacteria associated with community-dwellers was linked to increased frailty. The study concluded, “Collectively, the data support a relationship between diet, microbiota and health status, and indicate a role for diet-driven microbiota alterations in varying rates of health decline upon aging.”

More studies will certainly be needed to continue to elucidate the intricacies of the gut microbiota and its far-reaching health effects.  However, this study made some interesting connections that build on previous findings that support a decrease in gut bacterial types and diversity as we age, contributes to poor health.

Dr. Elie Metchnikoff (from a 104 years ago) would be pleased to know we are finally proving what he believed: Probiotic bacteria obtained from eating and drinking  fermented yogurt and milk, maybe a major anti-aging technology, as is the increase in  diversity of the commensal bacteria which is supported by prebiotics, probiotics, diet, and lifestyle.2 


  1. M.HJ. Claesson, et al., “Gut microbiota composition correlates with diet and health in the elderly.” Nature. 2012 July 13;ePub.
  2. E. Metchnikoff, The Prolongation of Life, Knickerbocker Press, 1908.