Inclusivity and diversity are aspects recently appreciated and demanded more than ever on social media and television. All humans have entire ecosystems of microbes living in their bodies. Each individual micro-organism has their own abilities. Some which contribute to our body’s health. The love of diversity must be shared even among those communities that are invisible to the naked eye. Microbiomes who are largely diverse are most likely to lead their host a healthy life. Therefore, they live longer. It is believed that microbial changes (negative or positive) help drive or “decelerate” the aging process. However, other studies confirm that as you age the quality and diversity of microbes decreases. Which is the cause of which? Does microbial changes drive aging or does aging drive microbial changes? Before coming to any conclusion, let’s explore the curious linkages between gut bacteria and aging!
Micro-organisms play a key role in our body that most people overlook, such as degradation of food, vitamin synthesis, battling harmful microbial species, and pretty much maintaining our intestinal barrier. Though these traits sound awesome already, wouldn’t it be incredible if microbes were shaping how we age? It sounds straight out of a scifi movie but science has shown this could likely be true. NIA-supported (National Institute on Aging) research tackles the idea that microbial changes could likely be connected with age-related diseases, obesity, cancer, depression, metabolic disorders, and obesity. In a newer study a “research team analyzed gut microbiome genetic sequences and a wealth of other health and survival outcomes data from more than 9,000 people between the ages of 18 and 101.” (1) Adults with diversity in their microbes tended to live healthier lives than those who had less. The microbiome-inclusive participants’ blood presented “lower levels of LDL cholesterol and higher levels of vitamin D, but also more beneficial blood metabolites produced by gut microbes.” (1) They also had better physical agility contrary to microbiome-non-inclusive participants who not only had less physical agility but also used more medication and had twice the chance to die during the study period. The message is clear, peers with diversity in their microbes lead long, healthy lives. When they become less diverse, outcomes like less mobility, higher chances of disease, and death rate become more noticable. Factors like these are commonly associated with age-related conditions. The same interesting event happened when microbiota of older African turquoise killifish was compared to the young. However this time, age was brought to the table. Older fishes had more potentially harmful microbes species while the younger were enriched with good, diverse microbiomes. Other research done on rodents exemplifies ties between microbial changes and aging. The rodents showed that disruptions to gut bacteria worsen intestinal stem cells’ ability to regenerate, leading to problems/diseases in the intestinal barrier often associated with age-related conditions. And fascinately, in a 2017 study, young germ-free mice “developed inflammation that is indicative of aging”(2) when transplanted gut microbes from older mice.
To counteract the “microbial changes = aging” argument let’s discuss it’s opponent, the “aging = microbial change” argument. Clinical studies reported differences between elders and young individuals. The microbial diversity decreases as one gets older to respond to changes like weakened immune strength, changes in diets and lifestyle, reduced mobility, medication, and more. This makes sense giving to the fact that medication has been proven to disturb your microbial composition regardless of age. One may argue, though, that people who are older are likely to take more medications than adults or children hence you can make a connection between aging and disruptions in gut microbiomes. This argument does not stand strong because sickly children and adults exist. Even so, regardless of how many diseases you have and your age, in one way or another your gut bacteria will be affected. Does this extinguish the possibility that aging can cause microbial changes? Short answer, no. Long answer, as said in the Journal “Translational Medicine of Aging,” a key transition from healthy adult to elderly microbiota is characterized by a decrease in microbial diversity.
How do you define the aging process? Aging is a real mystery, what are the causes and why do we age? But let’s define age as an “optimization of changes/adaptations at an individual level to achieve a better functional healthspan.” (3) Apply this to our “aging = microbial change” argument. To maintain itself as we grow old our body is obligated to adapt, hence our gut bacteria won’t stay the same as we grow. “Throughout the human lifespan, gut microbiome follows some predictable patterns, with rapid change from infancy to age three, stability up until middle age, and then accelerated change starting in late adulthood.”(1) Microbial changes appear to cause aging in animals. But there is a keyword we pay more attention to, that is the word animal. Yes, research has shown that less diverse microbes can propel aging. However that can’t be exactly true for humans. Scientists have only found associations and linkages but never profound evidence to prove otherwise. Remember microbiology is an evolving field. We can’t certainly say our gut bacteria shapes how we age but there is much to learn. Here is one truth though, your gut bacteria will change as you grow. Will it cause you to age faster? Well, that depends on future discoveries.
What can you do for your body that will lose microbial diversity either because you are aging or it will age faster because your microbes are changing. For both situations, regardless of one being more accurate than another, the best thing you can do for your body is exercise, eat healthy foods, and regulate your use of antibiotics. Your body will thank you and those little guys inside you will thank you.
(2021) ‘Unique gut microbiome patterns linked to healthy aging, increased longevity.’ National Institute on Aging. https://www.nia.nih.gov/news/unique-gut-microbiome-patterns-linked-healthy-aging-increased-longevity
Wenner, Melinda. (2021). ‘Gut Bacteria Change as You Get Older—and May Accelerate Aging.’ Scientific American. https://www.scientificamerican.com/article/gut-bacteria-change-as-you-get-older-and-may-accelerate-aging/
Lung Thomas, Di Cesare Pasquale, Risch Lorenz, Nydegger Urs, and Risch Martin. (2021). ‘Elementary Laboratory Assays as Biomarkers of Ageing: Support for Treatment of COVID-19?’
Kim Minhoo, A.Benayoun Bérénice. (2021). ‘The microbiome: An emerging key player in aging and longevity.’ ScienceDirect. https://www.sciencedirect.com/science/article/pii/S2468501120300146