How Your Gut Microbiome Changes with Age and How It Impacts Your Health


How Your Gut Microbiome Changes with Age and How It Impacts Your Health

Inside your gut is a living ecosystem known as your microbiome. This internal ecosystem that you carry around is made up of as many as 100 trillion bacteria. In fact, the bacteria in your gut weigh around 4 pounds. Like your fingerprint, your gut microbiome is unique and no one has the exact bacterial signature that you do. Plus, we now know the bacteria that reside in your individual ecosystem impact health in a number of ways. At the most simplistic level, these microbes, protect your intestinal tract. Their presence keeps bacteria and fungi that cause illness from taking up valuable real estate in the gut and causing illness. They do this partially by secreting chemicals that keep unsavory bacteria at bay and by competing for resources.

As scientists are discovering, healthy gut bacteria aren’t just important for gut health, 70% of your immune system is impacted by them. Plus, these gut citizens influence your mood by interacting with the enteric nervous system, the portion of your nervous system that lies in your gut. Gut bacteria may even play a role in whether an individual develops heart disease. Some bacteria produce a compound called trimethylamine-N-oxide, also known as TMA0 when animal-based foods enter your gut. Research shows higher levels of TMAO in the blood is linked with a greater risk of heart attack and stroke. Plus, gut bacteria also influence the activity of the immune system, including inflammation, and we now know that inflammation is linked with almost every chronic disease.

Gut Microbiome Bacteria and Aging

With gut bacteria playing such a critical role in health, you might wonder whether these critters play a role in aging. When you’re born, assuming you travel through the vaginal canal and if you aren’t delivered through C-section, your first exposure to bacteria is through mom’s birth canal. Exposure to healthy bacteria from mom is important for priming your immune system. Studies show that babies born via C-section and don’t get this exposure, are at higher risk of autoimmune and allergic diseases, including type 1 diabetes and asthma.

From birth to death, organisms in your gut impact your health. During infancy, your microbiome is dominated by a group of bacteria called Bifidobacterium. As you mature into an adult, you lose Bifidobacterium and become colonized with more Bacteriodetes and Firmicutes. During early adulthood, you have a predominance of Firmicutes but as the years advance, your microbiome becomes dominated by Bacteriodetes. In addition, you have fewer of other kinds of bacteria. In other words, your gut microbiome becomes less diverse.

What’s the significance of these changes? Studies have linked the loss of gut diversity in older people with greater frailty and increased markers of inflammation. Although we still have much to learn about the gut microbiome, including what types of bacteria are the most beneficial, a more diverse population of gut bacteria is linked with more vibrant health and, potentially, a lower risk of disease.

Improving Your Gut Microbiome Diversity

If a lack of microbial diversity is linked with inflammation, frailty, and age-related health problems, cultivating a diverse population of organisms is important for successful aging. How can you improve the diversity of your own gut microbiome?

As you might expect, what you eat matters. Healthy gut bacteria thrive on fermentable carbohydrates called prebiotics. These are carbohydrates that the amylase enzymes your body makes can’t break down and pass intact into the large intestinal tract. Here, these intact carbs are met by bacteria that DO have the enzymes to break them down. When they do, they produce short-chain fatty acids that bathe the lining of the large intestines.

One short-chain fatty acid produced by gut bacteria, butyric acid, serves as a source of energy for intestinal cells and has anti-inflammatory activity. In fact, preliminary studies show a link between butyric acid and a lower risk of colon cancer. Prebiotics also promote the growth of other healthy gut bacteria. The best sources of prebiotics include Jerusalem artichokes, asparagus, oatmeal, legumes, onions, and bananas. Prebiotics are a type of fiber but not all fiber is prebiotic.

The Power of Probiotics

Another approach to increasing gut diversity is to add more beneficial bacteria to your gut in the form of probiotics. You can do this by eating more fermented foods, including yogurt with active cultures and fermented vegetables. These foods offer benefits over buying a commercial probiotic where you don’t know whether the strains are viable at the time you take them. Independent analysis of probiotic supplements shows that some contain fewer organisms than listed on the label and that not all of the organisms survive. Plus, when you consume probiotics from foods, you get the other benefits the food offers. In the case of fermented vegetables, you get fiber, vitamins, minerals, and phytonutrients. Doesn’t that sound better than swallowing a pill?

It’s also important to avoid exposures to things that harm gut bacteria, such as antibiotics. The most obvious source of exposure to antibiotics is from an antibiotic prescription you get from your doctor – but that’s not the only one. Another source of antibiotic exposure you might not have considered is factory-farmed meat. Animals raised in a factory setting routinely get antibiotics to lower their risk of infection since they live in crowded conditions. These antibiotics can, in turn, enter your gut when you eat the meat. If you consume meat or dairy products, buy organic products where the animal was not exposed to antibiotics.

The Bottom Line

It’s not surprising that gut bacteria play a role in health and aging. They influence health in a variety of ways – by influencing nutrient absorption and how much energy you extract from food, and by altering immune function. Plus, gut bacteria also produce some vitamins, including B vitamins and vitamin K. So, make sure you’re eating a diversity of fiber-rich foods, including prebiotic fiber and including some fermented foods in your diet. Gut bacteria matter more than you think.



Clin Perinatol. 2011 Jun; 38(2): 321–331. doi: 10.1016/j.clp.2011.03.008
Microbial Biotechnology. “Microbiota and healthy aging: observational and nutritional intervention studies”
Curr Opin Biotechnol. 2013 Apr;24(2):160-8. doi: 10.1016/j.copbio.2012.08.005. Epub 2012 Aug 30.


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