Mental health can be influenced by the gut

Published on: 04/26/2024

In the whirlwind of adolescence, with packed schedules, academic pressures, and social dynamics, teens often find themselves choosing convenience foods over nutritional value due to their convenience and availability. Unsurprisingly, studies tracking the consumption of foods by teens have revealed that adolescents aged 12-18 have the lowest intake of vegetables and fruits compared to any other age group. This dietary deficiency impacts their overall health and deprives them of essential nutrients vital for gut health, including fiber and prebiotics. The gut microbiome of ‘junk food’ often lacks the balance that is crucial for maintaining a healthy digestive system. This imbalance can lead to digestive problems, an increased risk of metabolic disorders and a higher risk for anxiety and depression.

“The composition of the gut microbiota in adolescents is distinct from that of children and adults, which supports the premise that the gut microbiota continues to develop during adolescence toward an adult-like profile.” 

Probiotics and prebiotics are very popular dietary supplements. After vitamins and minerals, more American adults use probiotics or prebiotics than any other supplement (1). And there is good reason for this. Not only is gut health becoming recognized as the foundation for overall physical health, but recent studies point to the influence a healthy gut has on mental health as well. Given the high rate of depression amongst adolescents, this prompts a closer examination of the gut-brain connection in this age group.

Probiotics and prebiotics promote health in many ways. For example, a gut full of “friendly” microbes will absorb more nutrients, discourage unfriendly microbes, and even reduce inflammation—all of which are beneficial to gut health and overall mental health and immunity. Besides supplements, many foods contain probiotics and prebiotics. 

What are probiotics and prebiotics?

Before we dive into the ways that probiotics, prebiotics (and other “biotics”) can impact our health, and how to get enough of them, here is what I mean when I talk about them:

  • Microbiome – In the large intestine of your gut are trillions of “friendly” microbes that naturally inhabit this area (2,3,4). Most of these microbes are bacteria, but there are also some health-promoting viruses and fungi. All of these tiny organisms living together are called the microbiome. Everyone starts with a unique microbiome at birth and this is influenced by many factors including what we eat and what supplements and medications we take (2,3).
  • Probiotics – Probiotics are “live microorganisms that are intended to have health benefits when consumed or applied to the body” (1). The word comes from the Greek words “pro” and “bios” meaning “for life” (4).
  • Prebiotics – Prebiotics are “nondigestible food components that selectively stimulate the growth or activity of desirable microorganisms” (1). They’re essentially food for the microbes in your gut and they’re used to help grow a diverse, thriving microbiome (3,5). 
  • Psychobiotics – Psychobiotics are probiotics that confer mental health benefits” (6).

Health benefits of pro-, pre-, and psychobiotics in teens

Maintaining a balance of gut microbes benefits teen health in so many ways. The list of positive health effects of a healthy gut microbiome seems to grow daily because of all of the research in this area. Some of the key benefits include helping to digest food and promote gut health, producing essential nutrients, influencing the immune system, improving moods and mental health, and even reducing the impact of inflammation and toxin-producing microbes (1,3,7). Two that we will focus on for this article are gut health and mental health.

Gut health

The microbiome helps maintain and improve gut health in many ways. It contributes to healthy bowel function and may help with conditions such as colitis (1,2). Some studies show that probiotics can help with diarrhea and constipation (1), especially if the cause is due to an imbalance in the gut microbiome (8) which may be due to antibiotic use, irregular eating patterns or other factors common in adolescents. 

How does a healthy gut microbiome achieve a healthy gut? There are a myriad of ways. First, certain microbes produce health-promoting substances such as short-chain fatty acids and certain B vitamins (4). These nutrients are absorbed by the body and go on to nourish other areas of the body. Other substances produced by gut microbes help to lower the pH of that part of the gut and reinforce its lining (9). The gut microbiome can also reduce inflammation, eliminate toxins, as well as boost the body’s ability to absorb essential minerals (4).

Mood, mental health, and psychobiotics

There is a growing area of research about nutritional psychiatry—the links between what we eat and how we feel mentally and emotionally (7). Many studies show the strength of this food-mood connection. For example, eating a high-quality, nutritious diet nourishes the brain, helps keep inflammation down, and helps us enjoy more stable moods (7). Plus, many chronic gut conditions are often accompanied by mood disorders such as depression and anxiety (6). As mentioned earlier, there is a subset of probiotics that have mental health benefits called “psychobiotics” (6).

A recent review of seven clinical trials published in the medical journal BMJ Nutrition Prevention & Health found that certain probiotic supplements, with and without prebiotics, were linked to “measurable reductions in depression” (10).

Lactobacillus probiotic supplementation in humans attenuated stress-induced increases in salivary cortisol and anxiety

How does gut health influence the mind and emotions? Via the “gut-brain axis.” Several parts of this axis foster constant communication in both directions between your gut and brain (6). Parts of the gut-brain axis include:

  • Some neurotransmitters and neurohormones are produced in the gut. For example, it’s estimated that 90-95 percent of the serotonin in the body is produced in the gut (6,7). Serotonin is the neurotransmitter that helps to regulate sleep, appetite, and emotions, and reduce pain (7). 
  • The digestive system contains 100 million nerve cells and is a hub for the immune system (7). 
  • A healthy gut microbiome helps to regulate the stress response and inflammation throughout the body (6). 
  • Some rodent studies suggest that the gut microbiome can influence levels of brain-derived neurotrophic factor (BDNF) in the central nervous system, thus impacting behavior (6).

All of these gut-brain activities are influenced by the gut microbiome and pro—or psycho—biotics (6,7). 

How to get enough probiotics and prebiotics in your teen’s diet

Pro- and prebiotics can be found in both foods and supplements. 

Probiotic foods

Many gut-healthy, fermented foods are produced with the help of bacteria. Some of these include yogurt, kefir, pickles, sauerkraut, miso, and kombucha (2). However, not all fermented foods still contain live active cultures of those bacteria by the time they get to the market or grocery store shelf (2,9). Your best bet is to choose fermented products from the refrigerated section (3) and check the product labels to ensure they contain “live active cultures” (2). Or better yet, make your own fermented foods. Also, some food companies are now fortifying unfermented foods (cereals, juices) with probiotics (9); so again, check your labels.

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Prebiotic (fiber-rich) foods

Many foods are rich in the insoluble fiber that health-promoting gut microbes need to thrive. These include whole grains (oatmeal, whole grain breads, and pastas), vegetables (asparagus, leeks, onions), starchy vegetables (sweet potatoes, corn), fruit (bananas), and legumes (beans, lentils, peas) (2,4). Enjoy a variety of these fiber-rich foods to naturally boost the health and biodiversity of your microbiome (3).

In addition to eating probiotic and prebiotic foods, it’s also a good idea to limit foods that can deplete your friendly gut microbes. This includes enjoying fewer processed foods that are high in sugars, artificial sweeteners, and saturated fats (2,3). 

Probiotic supplements

There are many strains of probiotic microbes available, each having unique effects. Some of the most common strains included in probiotic supplements include Lactobacillus, Bifidobacterium, Saccharomyces, Streptococcus, Enterococcus, Escherichia, and Bacillus (9). Many, but not all of these strains are similar to those found naturally in the microbiome (1). Supplement companies combine different strains of bacteria and yeasts in different amounts to create many unique supplements to choose from. 

Unlike with foods, the manufacture of probiotic supplements is not monitored in the US and some products have been found to have different or fewer probiotics than what’s listed on the label (8). This is why it’s important to choose a high-quality probiotic whenever possible. 

Some of the quality probiotics I recommend

Note that probiotic supplements should not be given to premature infants or people with severe illnesses or compromised immune systems without a recommendation from a qualified healthcare professional, as there have been reports of harmful effects (1).

Prebiotic supplements

Prebiotic supplements contain starches that the gut microbes consume and metabolize into beneficial compounds. These fiber-rich supplements may include inulin, GOS (galactooligosaccharides), FOS (fructooligosaccharides), and lactulose (4).

Final thoughts

Teen gut health is more than just an optimal digestive system. Gut health influences physical and mental health in a myriad of ways. One of the main things that you can do to help your teen foster their gut health is to nourish their gut microbiome. This includes enjoying probiotic (fermented) foods as well as prebiotic (fiber-rich) foods. This can be difficult in these independent teen years. Both probiotics and prebiotics are also available as dietary supplements when getting teens to eat a variety of foods proves difficult.

Do you need help optimizing your teen’s gut health, overall health, or mental health? As a registered dietitian, I’d love to help.

Book an appointment with me today to see if my services can help you.


  1. National Center for Complementary and Integrative Health. (2019, August). Probiotics: What You Need To Know.
  2. Harvard Health Publishing. (2022, November 14). Probiotics and prebiotics: what’s really important?
  3. Corliss, J. (2023, November 1). How a healthy gut helps your heart. Harvard Health Publishing.
  4. Ji, J., Jin, W., Liu, S. J., Jiao, Z., & Li, X. (2023). Probiotics, prebiotics, and postbiotics in health and disease. MedComm, 4(6), e420.
  5. Golen, T & Ricciotti, H. (2021, November 1). What are postbiotics? Harvard Health Publishing.
  6. Del Toro-Barbosa, M., Hurtado-Romero, A., Garcia-Amezquita, L. E., & García-Cayuela, T. (2020). Psychobiotics: Mechanisms of Action, Evaluation Methods and Effectiveness in Applications with Food Products. Nutrients, 12(12), 3896.
  7. Selhub, E. (2022, September 18). Nutritional psychiatry: Your brain on food. Harvard Health Blog.
  8. Harvard Health Publishing. (2022, February 2). Should you take probiotics?
  9. Office of Dietary Supplements. (2023, November 3). Probiotics: Fact Sheet for Health Professionals.
  10. British Medical Journal. (2020, July). Probiotics alone or combined with prebiotics may help ease depression.


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Nicole Roesch, RDN, LDN, CPT provides nutrition counseling services in-person and virtually in Palm Beach County, FL. She specializes in helping families create a positive relationship with real, wholesome food – through education, meal planning & behavioral changes that fit their lifestyle.

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