Bischoff - Winter 2016 Biotherapy Journal Review

Probiotics and Bacteriotherapy Reviews

Journal Citation:

Bischoff, SC. Microbiota and aging. Curr Opin Clin Nutr Metab Care. 2016; 19(1):26-30

Published Abstract

This article summarizes our current knowledge of changes in the intestinal microbiota in elderly people and centenarians. RECENT FINDINGS: Age-related processes comprise specific changes in the intestinal microbiota and related metabolic alterations. They result in 'inflamm-aging', which is associated with age-related inflammatory processes and diseases, including cachexia, frailty, cancer, and metabolic as well as neurological diseases. Age-related microbial changes consist of an increase in proteolytic bacteria and a decrease in saccharolytic bacteria. These changes are associated with sarcopenia and longevity, and might be attenuated by pre and probiotics. These findings could explain, at least in part, why probiotics have been successfully used in elderly people for the treatment of respiratory and gastrointestinal infections, and for the enhancement of vaccination responses. SUMMARY: The intestinal microbiota changes with age. These changes are of relevance in regard to morbidity and mortality in the elderly population. Dietetic (probiotics, prebiotics) and other lifestyle interventions might delay, or even reverse, such alterations.

Introduction & Background to Study

For many years, we have known that the population dynamics of many gut microbes commonly changes as we age. However, only recently have we been able to analyze the gut microbiome in large quantities, at rapid enough speeds, to make these types of analyses more comprehensive. This study reviews some of the more recent studies of the human gut biome in order to better understand the relationship between our aging process and our microbiome.

Materials & Methods

Review of published literature since 2010. No details were given regarding the selection process.

Study Results

The author’s review of recent literature points to the following revelations:

Age-related processes comprise specific changes in the intestinal microbiome and related metabolic alterations, resulting in increased inflammation (“inflamm-aging”), associated with age-related inflammatory processes and diseases, including cachexia, frailty, cancer, and metabolic as well as neurological diseases. Age-related microbial changes include an increase in proteolytic bacteria and a decrease in saccharolytic bacteria, and are associated with sarcopenia and longevity. 

Author’s Conclusions

The intestinal microbiota changes with age, and these changes are also associated with a number of age-related complications, including frailty, sarcopenia, inflammation-related malnutrition (cachexia), and infection. These findings could help explain why probiotics have been used successfully in some elderly populations for the treatment of respiratory and gastrointestinal infections, and for the enhancement of vaccination responses. Therefore, intervention strategies such as adapted diets, pre and probiotics, and other lifestyle factors, need to be explored further.

Reviewer’s Conclusions

Even with a formal training in microbiology and gerontology, this article was a difficult read. This is likely due to the fact that the concepts and terminology – indeed, the very area of study – is relatively new and rapidly evolving. Nevertheless, this review provides an insightful framework with which to understand the recent discoveries in the microbiome of aging humans.

The reader walks away with the feeling that the microbiome is so very young (continually and frequently renewed, since so many microbes are able to replicate in as little as 20 minutes) and adaptable (that is, so facile and quick to change, since so many microbes replicate in as little as 20 minutes), that changes in the microbiome are simply the response to the hosts’ changes in diet, environmental exposure and aging physiology. Yet, the resulting alterations in the microbiota may then be the cause of further physiological and immunological changes in the aging host.

For example, it is easy to understand how the microbiota of people in long-term care facilities would reasonably be less diverse than that of community dwellers. But then, is the loss of community-associated microbiota a contributing factor to the increased frailty, also associated with age? And if there is a cause-and-effect, can it be altered by a diet or microbiota associated with a younger, healthier age? One thing is for sure: further studies and even long-term intervention studies could help us understand and maybe even alter the changes that we have long attributed simply to “old age.”