Gut Punch: Supporting Gut Health After TBI

Authored by guest blogger: Faith M Stokes, PT, DPT, PRPC, WCS, OCS, FAAOMPT

You can follow Faith on Instagram @ThePHFellow and on LinkedIn

If you've spent any time reading about health over the past decade, you've probably encountered the term gut-brain axis.

Although the phrase sounds trendy, the concept is not particularly new. Scientists have been studying communication between the brain and gastrointestinal tract for decades, and modern microbiome research has expanded our understanding of the many ways these systems interact (Ahmed 2022).

For individuals with traumatic brain injury (TBI), this relationship is particularly interesting because brain injury can influence many of the same factors that affect digestive health, including sleep, stress, physical activity, eating habits, and the microbiome itself.

Rather than viewing gut health as a separate goal, it may be more helpful to think of it as one component of overall recovery.

Why Does TBI Affect the Gut?

The gut-brain axis describes the ongoing communication between the gastrointestinal tract and the nervous system. That communication occurs through several pathways, including nerves, hormones, immune signaling, and the microbiome (Appleton 2018).

When most people think about the consequences of TBI, they think about symptoms such as headaches, dizziness, memory changes, or difficulty concentrating. However, brain injury can also influence factors that affect digestion.

Changes in sleep, stress, physical activity, eating habits, medications, and daily routines can all influence gastrointestinal function. For some individuals, this may contribute to symptoms such as constipation, reflux, bloating, abdominal discomfort, or changes in bowel habits (Lin 2025).

Clinically, digestive symptoms are often treated as completely separate from other aspects of recovery. In reality, many of the lifestyle factors that support brain health also support gastrointestinal health. Digestive symptoms after TBI are common and, in many cases, manageable.

Move for Your Brain and Gut

Physical activity appears in almost every discussion about health, and for good reason. Movement influences cardiovascular health, sleep quality, stress regulation, mood, metabolic health, and overall function. It also supports digestive health (Piercy 2018).

One reason is that physical activity helps regulate gastrointestinal motility, which refers to how material moves through the digestive tract. Regular movement is often associated with improved bowel regularity and digestive function.

Movement also supports many of the factors that influence gut health indirectly. People who are physically active often experience improvements in sleep, stress management, and overall well-being, all of which can affect digestive health. That said, more is not always better.

Many people assume exercise exists on a simple spectrum where increasing intensity automatically produces increasing benefit. The reality is more nuanced. Athletes have long recognized that intense training can sometimes trigger digestive symptoms, including bloating, abdominal discomfort, reflux, diarrhea, or nausea (de Oliveira 2009).

This doesn’t mean exercise is harmful. It means exercise has a dose-response relationship.

For many individuals recovering from TBI, consistent low-to-moderate intensity activity may be more beneficial and sustainable than sporadic periods of very intense exercise.

Walking, cycling, swimming, resistance training, and recreational activities can all contribute to overall health. The best exercise program is often the one you can maintain consistently.

Sleep Matters

It may seem unusual to discuss sleep in an article about gut health, but sleep influences many of the behaviors and physiological systems involved in both brain and digestive health.

Sleep disruption is common after TBI. Some individuals struggle to fall asleep, others wake frequently throughout the night, and many report feeling unrefreshed even after what appears to be an adequate amount of sleep (Wickwire 2020). Unfortunately, poor sleep rarely stays confined to the bedroom.

Sleep deprivation can affect appetite regulation, decision making, food choices, stress response, and physical activity levels. Most people can relate to the experience of reaching for convenience foods or skipping exercise after a poor night's sleep (Frank 2017).

Research suggests a bidirectional relationship between sleep and the gut microbiome, with disruptions in one potentially influencing the other (Lin 2024).

For that reason, sleep is often considered a foundational health behavior, as improvements may influence multiple aspects of recovery simultaneously.

Improving sleep may not solve every digestive symptom, but it often creates a stronger foundation for the habits that support recovery.

Build a Microbiome-Friendly Plate

Discussions about gut health frequently become focused on supplements.

Before purchasing a probiotic, it may be worth considering a simpler question:

What are the microorganisms already living in your gut eating?

Many of the bacteria that inhabit the digestive tract rely on fibers and compounds found in plant foods. Fruits, vegetables, legumes, nuts, seeds, and whole grains provide nutrients that help support microbial diversity.

One of the most practical nutrition goals is not perfection. It’s variety.

Different microbes utilize different nutrients. A diverse intake of plant foods helps create a more diverse nutritional environment within the gut (Valdes 2018).

Before you try and eliminate a bunch of food, start considering what you can add that will move you closer to your goals and let those additions naturally replace the less healthy options.

A simple strategy is to look for opportunities to increase the variety of plant foods consumed throughout the week.

Progress Fiber Slowly

Fiber is one of the most frequently recommended nutrients for gut health, but it is also one of the most common causes of frustration.

A typical scenario looks something like this: Someone decides to eat healthier and dramatically increases vegetables, beans, whole grains, and fiber supplements all at once. A few days later they experience bloating, gas, and abdominal discomfort.

The conclusion is understandable.

"Fiber doesn't work for me."

Often, the issue is not fiber itself. The issue is speed.

The gut microbiome adapts to dietary patterns over time. When fiber intake increases rapidly, digestive symptoms can occur before adaptation has had an opportunity to take place (Makki 2018). Increasing fiber gradually allows both the digestive system and gut microbiome time to adapt (Dahl 2015). In practice, patience often outperforms enthusiasm.

Try Fermented Foods

Fermented foods have received considerable attention in recent years, but they have been part of the human diet for centuries.

Foods such as yogurt, kefir, kimchi, and sauerkraut contain microorganisms produced during fermentation. Researchers have become increasingly interested in how these foods may influence the microbiome and immune function (Marco 2016).

One area of interest is inflammation.

Inflammation is a normal component of healing and recovery. Following TBI, researchers have explored how inflammatory processes may contribute to symptoms and long-term outcomes (Simon 2017).

Studies have found that diets rich in fermented foods may influence inflammatory markers and support microbial diversity. While fermented foods should not be viewed as a stand-alone treatment for TBI, they represent a practical dietary strategy that may support overall health (Wastyk 2021).  

As with fiber, starting slowly is often helpful.

The best starting dose is usually the amount that does not cause significant digestive discomfort. From there, intake can be increased gradually as tolerated.

Managing GI Discomfort

One of the challenges of changing dietary habits is distinguishing between adaptation and intolerance. A temporary increase in gas or bloating does not necessarily mean a food is harmful. Sometimes it reflects the digestive system adapting to a change in dietary intake.

If symptoms increase after introducing more fiber or fermented foods, consider simplifying the process.

1.    Slow the rate of fiber progression.

2.    Reduce serving sizes.

3.    Increase fluid intake.

4.    Change one variable at a time rather than several simultaneously.

This approach makes it easier to identify what is helping, what is not, and which changes are sustainable long term.

Need More Support?

Lifestyle interventions can be remarkably effective, but they are not a replacement for individualized healthcare.

Persistent gastrointestinal symptoms, significant abdominal pain, unexplained weight loss, worsening symptoms, or concerns about nutrition deserve additional evaluation.

Depending on your needs, support may come from:

• A medical provider

• A registered dietitian

• A lifestyle medicine practitioner

• A pelvic health physical therapist

• VA Whole Health services

  
  

Small Changes Count

One of the easiest mistakes to make is attempting to change everything at once. Sustainable habits are often built one step at a time.

That step might be:

1.    Taking a daily walk.

2.    Improving sleep consistency.

3.    Adding another serving of vegetables.

4.    Trying a fermented food.

5.    Drinking more water.

The gut-brain axis is complex. The lifestyle habits that support health are not. Sleep, movement, nutrition, and stress management continue to show up throughout both recovery and health literature.

You do not need a perfect plan to move forward. Often, the next reasonable step is enough.

References:

1.      Ahmed, M. (2022). Gut-Brain Axis and Food. British Journal of Gastroenterology, 4(1), 242-248.

2.      Appleton J. (2018). The Gut-Brain Axis: Influence of Microbiota on Mood and Mental Health. Integrative medicine (Encinitas, Calif.), 17(4), 28–32.

3.      Dahl, W. J., & Stewart, M. L. (2015). Position of the Academy of Nutrition and Dietetics: Health Implications of Dietary Fiber. Journal of the Academy of Nutrition and Dietetics, 115(11), 1861–1870. https://doi.org/10.1016/j.jand.2015.09.003

4.      de Oliveira, E. P., & Burini, R. C. (2009). The impact of physical exercise on the gastrointestinal tract. Current opinion in clinical nutrition and metabolic care, 12(5), 533–538. https://doi.org/10.1097/MCO.0b013e32832e6776

5.      Frank, S., Gonzalez, K., Lee-Ang, L., Young, M. C., Tamez, M., & Mattei, J. (2017). Diet and Sleep Physiology: Public Health and Clinical Implications. Frontiers in neurology, 8, 393. https://doi.org/10.3389/fneur.2017.00393

6.      Lin, D., Howard, A., Raihane, A. S., Di Napoli, M., Cáceres, E., Ortiz, M., Davis, J., Abdelrahman, A. N., & Divani, A. A. (2025). Traumatic Brain Injury and Gut Microbiome: The Role of the Gut-Brain Axis in Neurodegenerative Processes. Current neurology and neuroscience reports, 25(1), 23. https://doi.org/10.1007/s11910-025-01410-0

7.      Lin, Z., Jiang, T., Chen, M., Ji, X., & Wang, Y. (2024). Gut microbiota and sleep: Interaction mechanisms and therapeutic prospects. Open life sciences, 19(1), 20220910. https://doi.org/10.1515/biol-2022-0910

8.      Makki, K., Deehan, E. C., Walter, J., & Bäckhed, F. (2018). The Impact of Dietary Fiber on Gut Microbiota in Host Health and Disease. Cell host & microbe, 23(6), 705–715. https://doi.org/10.1016/j.chom.2018.05.012

9.      Marco, M. L., Heeney, D., Binda, S., Cifelli, C. J., Cotter, P. D., Foligné, B., Gänzle, M., Kort, R., Pasin, G., Pihlanto, A., Smid, E. J., & Hutkins, R. (2017). Health benefits of fermented foods: microbiota and beyond. Current opinion in biotechnology, 44, 94–102. https://doi.org/10.1016/j.copbio.2016.11.010

10.    Piercy, K. L., Troiano, R. P., Ballard, R. M., Carlson, S. A., Fulton, J. E., Galuska, D. A., George, S. M., & Olson, R. D. (2018). The Physical Activity Guidelines for Americans. JAMA, 320(19), 2020–2028. https://doi.org/10.1001/jama.2018.14854

11.    Simon, D. W., McGeachy, M. J., Bayır, H., Clark, R. S., Loane, D. J., & Kochanek, P. M. (2017). The far-reaching scope of neuroinflammation after traumatic brain injury. Nature reviews. Neurology, 13(3), 171–191. https://doi.org/10.1038/nrneurol.2017.13

12.    Valdes, A. M., Walter, J., Segal, E., & Spector, T. D. (2018). Role of the gut microbiota in nutrition and health. BMJ (Clinical research ed.), 361, k2179.https://doi.org/10.1136/bmj.k2179

13.    Wastyk, H. C., Fragiadakis, G. K., Perelman, D., Dahan, D., Merrill, B. D., Yu, F. B., Topf, M., Gonzalez, C. G., Van Treuren, W., Han, S., Robinson, J. L., Elias, J. E., Sonnenburg, E. D., Gardner, C. D., & Sonnenburg, J. L. (2021). Gut-microbiota-targeted diets modulate human immune status. Cell, 184(16), 4137–4153.e14. https://doi.org/10.1016/j.cell.2021.06.019

14.    Wickwire E. M. (2020). Why sleep matters after traumatic brain injury. Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine, 16(S1), 5–6. https://doi.org/10.5664/jcsm.8872