The gut microbiota changes with aging

While the gut microbiota tends to remain relatively stable in adulthood, as people age, some patterns of decline become apparent. After the age of 60, the gut microbiota varies greatly from person to person (as has been observed in infants), with a decrease in diversity and core functions (e.g., the production of short-chain fatty acids from fiber fermentation) and an enrichment of previously non-dominant bacteria that are potentially harmful.

However, whether age-related changes in the gut microbiota are a good or not-so-good sign is a matter of debate. While fecal microbiota transplant guidelines recommend excluding donors over the age of 60, stools from centenarians may well become one day a sample of choice for transplantation.

Looking at the microbiomes from over 9,000 adults from 18 to 101 years old, scientists found that those that showed the greater change in the make-up of the gut microbiome tended to be healthier and live longer, whereas the microbiomes of less healthy individuals remain relatively stable and they tend to die earlier. As a result, it seems that gut microbes tend to adapt to the body, resulting in a particular composition when people are young and changing to another state as they age. So age-related changes in the gut microbiota are not necessarily harmful for everybody.

Before affirming whether successful aging might lie in the gut microbiota, scientists also need to explore to what extent healthy aging drives changes in the gut microbiota or vice versa.


Findings in mice prove that the gut microbiota can rejuvenate the aging brain and immune system

Although a decline in cognitive and immune function is common as people age, little is known about the role of the gut microbiota in that. A recent study by Marcus Boehme from University College Cork in Ireland and colleagues found that fecal microbiota transplantation from young to old mice slowed down cognitive impairments, restored some chemicals involved in learning and memory, and lessened inflammation, which is increased across all the body’s systems as people age.

The findings add to the previous growing body of studies that support the hypothesis that changes in gut microbiota composition in aging may be related to age-related changes in cardiovascular, immune, and gastrointestinal health.

While it appears that the microbiome is important for a healthy brain and immune system in old age, mice are not humans and we should wait for more studies that help translate these remarkable findings to humans.

Meanwhile, a good starting point for aging well is to look after lifestyle and diet—both well-known ways to improve well-being and quality of life by involving the gut microbiome.


What can you do to alleviate the effects of gut microbiota changes into old age?

Age-related changes in the gut microbiota are not trivial, as they have been related to frailty. In fact, physical and mental health, along with lifestyle, matter more than genetics in terms of having a gut microbiota that is in good shape.

The goal now is to look at ways to intervene in everyday life, so as to attenuate the effects of aging on the gut microbiota and other systems in the body. Science-based approaches include administering specific strains of bacteria and dietary prebiotics, preferably in personalized dietary interventions.


  • People over 50 should ensure their daily intake of fiber, B vitamins, vitamin D and iron, with this age group usually at risk of deficiency.
  • A huge variety of dietary fibers should be encouraged in older adults, not only to avoid constipation, which is a common issue in this age group, but also to expand the functional capabilities of the gut microbiota, which tend to diminish as humans age. When changes in dentition and swallowing preclude older adults from consuming fiber-rich foods, prebiotics can be a good alternative.
  • Probiotics either as supplements or via probiotic-enriched foods such as yogurts may be of interest as part of a balanced diet, preferably those enriched in Bifidobacterium species due to their gradual decrease in the aged gut microbiota. Probiotic beneficial bacteria have been shown to increase beneficial bacteria in the gut and improve certain immunity parameters. In that regard, the term “gerobiotics” has been coined to define those probiotic strains and their derived postbiotics that can attenuate some age-related processes.


Take-home messages:

  • Although your gut microbiota changes as you age, whether such changes are a good or not-so-good sign is a matter of debate for scientists.
  • Changes in gut microbiota composition in aging may be related to age-related changes in cardiovascular, immune, and gastrointestinal health.
  • A balanced diet with prebiotic fibers and probiotics may help alleviate the effects of gut microbiota changes as people age.



Claesson MJ, Jeffery IB, Conde S, et al. Gut microbiota composition correlates with diet and health in the elderly. Nature. 2012; 488(7410):178-184. doi: 10.1038/nature11319.

Biagi E, Franceschi C, Rampelli S, et al. Gut microbiota and extreme longevity. Curr Biol. 2016; 26(11):1480-1485. doi: 10.1016/j.cub.2016.04.016.

Cammarota G, Ianiro G, Tilg H, et al. European consensus conference on faecal microbiota transplantation in clinical practice. Gut. 2017; 66(4):569-580. doi: 10.1136/gutjnl-2016-313017.

Wilmanski T, Diener C, Rappaport N, et al. Gut microbiome pattern reflects healthy ageing and predicts survival in humans. Nat Metab. 2021; 3:274-286. doi: 10.1038/s42255-021-00348-0.

Boehme M, Guzzetta KE, Bastiaanssen TFS, et al. Microbiota from young mice counteracts selective age-associated behavioral deficits. Nature Aging. 2021; 1:666-676. doi: 10.1038/s43587-021-00093-9.

Cryan JF, Boehme M, Dinan TG. Is the fountain of youth in the gut microbiome? J Physiol. 2019; 597(9):2323-2324. doi: 10.1113/JP277784.

Ragonnaud E, Biragyn A. Gut microbiota as the key controllers of “healthy” aging of elderly people. Immun Ageing. 2021; 18:2. doi: 10.1186/s12979-020-00213-w.

Skillington O, Mills S, Gupta A, et al. The contrasting human gut microbiota in early and late life and implications for host health and disease. Nutr Healthy Aging. 2021; 6:157-178. doi: 10.3233/NHA-210129.

Tsai YC, Cheng LH, Liu YW, et al. Gerobiotics: probiotics targeting fundamental aging processes. Biosci Microbiota Food Health. 2021; 40(1):1-11. doi: 10.12938/bmfh.2020-026.