How Our Microbiome Changes As We Age

by Lacy Kuester MS, MPP, RDNLifestyle
The Microbiome

Why Your Microbiome Matters

The bacteria in your intestines (collectively known as your gut microbiome, flora, or microbiota) are numerous and diverse. And that’s a good thing. Different bacteria serve different functions, such as helping you metabolize certain nutrients, producing neurotransmitters, regulating your immune function, and stimulating your digestive system. The helpful bacteria in your gut play another key role: when they set up camp in your intestines, they prevent bad bacteria from finding the real estate to do the same (1). Your gut microbiome is therefore beneficial for health promotion and disease prevention.

Factors that Influence Our Microbiome as We Age

Your microbiome is as unique to you as your fingerprint, but unlike your fingerprint your microbiome can change. Because bacteria are living organisms, their ability to survive and reproduce is dependent on their (i.e. your) environment. The food you eat becomes the food that they eat. The toxins in your environment become toxins in their environment. The antibiotics you take to kill off bad bacteria also kill some of your good bacteria (2, 3, 4). Another factor that influences our gut bacteria is age (2). This could be due to several factors including:

  • Changing tastes. As we age, we naturally lose our ability to taste flavors. What remains is our tongue’s ability to recognize sweet and salty stimulants. For many older adults, this leads to a preference for high-sugar or high-salt foods. Unfortunately, both of these are harmful to the gut, creating an inhospitable environment for good bacteria. Older adults also tend to eat a less varied diet, favoring a limited menu of familiar foods, but a diversity of foods is needed to feed a diverse microbiome (2, 3).
  • Increased intake of medications. Many common medications including NSAIDs, steroids, antibiotics, and PPIs can damage the gut and your microbiome (2, 4). A quarter of people aged 65 to 69 take at least five prescription medications. That statistic nearly doubles for adults in their 70s (5). While medications can be an important tool for disease management, it is important that you understand that they can have unintended consequences for your gut.
  • The cumulative effect of environmental toxins. Pesticides on food, mold in your environment, and toxins in your toiletries and home cleaning products all harm your gut and microbiome (3, 4). Exposing your body to these stressors over the course of your lifetime likely hinders your good bacteria from flourishing.

Promoting a Healthy Gut Microbiome

You have the power to make your gut a microbe-friendly place. Luckily, the factors that support a healthy microbiome also support cognitive health, so the following strategies are all compliant with the Bredesen Protocol.

  • Consume an organic, plant-based diet with lots of diversity. Your microbes will thank you for the abundance of micronutrients and fiber while holding off on the harmful pesticides. Make sure to change up what you eat each day. Different foods support different bacteria while also providing you with a wider variety of nutrients. Incorporate a rainbow of fruits and veggies and switch up your healthy protein and fat sources.
  • Eat more good microbes. Good bacteria are naturally found in many foods, especially fermented foods. Examples include sauerkraut, kimchee, pickled vegetables, and kombucha. When choosing a fermented food, look for the liquid in the bottle or jar to be cloudy. If the liquid is translucent (even if it has color), the item is likely only pickled, not fermented, so it does not have any bacteria. Note: It can be easy to over-consume kombucha because most bottles contain multiple servings. If you choose to add kombucha to your diet, please limit yourself to one serving per day (check the label. This is usually 8 ounces, or 1 cup).
  • Add flavor to food by using herbs and spices instead of salt and sugar. It’s important to limit sugar and salt both for your gut health and your cognitive health. Herbs and spices can give you that flavor boost while also upping your phytonutrient intake. It’s a win-win!
  • Work with your doctor to reduce unnecessary medications. Some of the common medications that harm your gut are used to control conditions that you can improve through diet or lifestyle changes. Talk to your doctor about the changes you could make to improve your health and reduce your prescriptions.
  • Limit your exposure to toxins. We encounter pesticides in the food we eat, chemicals in the water we drink, mold the air we breathe, and a huge number of toxins in the toiletries and cosmetics that we put on our bodies. These are harmful to us and to our microbes. The resources below can help you pick the right foods and products to minimize your toxic burden.

    • Choosing organic produce, grass-fed meats, and pasture-raised poultry reduces exposure to toxins in these foods (4).
    • You can see how your neighborhood water quality stacks up and get a filter recommendation based on the unique chemical composition of your supply by visiting the EWG Tap Water Database.
    • Skin Deep by EWG is a resource that evaluates the toxicity of toiletries, cosmetics, and home cleaning products. You can peruse it for the brands you use and to seek out better alternatives, if you need them.
    • Your health care practitioner can test and treat you for mold exposure, and experts can help remove it from your home if it is a problem.


  1. Fuller, R., & Perdigón, G. (2003). Gut flora, nutrition, immunity and health. Oxford ;: Blackwell Pub.
  2. Woodmansey, E., McMurdo, M., Macfarlane, G., & Macfarlane, S. (2004). Comparison of compositions and metabolic activities of fecal microbiotas in young adults and in antibiotic-treated and non-antibiotic-treated elderly subjects. Applied and Environmental Microbiology, 70(10), 6113–6122.
  3. Lerner, A. & Matthias, T. (2015). Changes in intestinal tight junction permeability associated with industrial food additives explain the rising incidence of autoimmune disease. Autoimmunity Reviews, 14, 479–489. j.autrev.2015.01.009
  4. Myers, Amy. (2015). The autoimmune solution. New York, NY: HarperOne.
  5. Boodman, S.G. (2017, December 09). The other big drug problem: Older people taking too many pills. The Washington Post. Retrieved from