Despite following aggressive antimicrobial treatment protocols and making dietary changes, many patients experience ongoing problems with SIBO. In fact, two-thirds of SIBO cases are chronic or relapsing in nature. (1) A growing body of research suggests that stress, trauma, and nervous system deregulation may be to blame for recalcitrant SIBO. Read on to learn about how stress contributes to SIBO and why managing stress is essential for restoring gut health over the long term.
The Link between the HPA Axis and the Gut Microbiota
I’ve talked a lot about the function of the HPA axis and its role in health and disease, but for those who are newer to this subject, let’s start with a review. The HPA axis is a dynamic system, comprising the hypothalamus, pituitary, and adrenal glands, that regulates the body’s response to stress. Stress activates the HPA axis and begins a cascade of signals that results in the release of hormones and neurotransmitters like cortisol, epinephrine, and norepinephrine. While the stress response is typically protective in the face of acute stress, it can become harmful over the long term. In fact, chronic activation of the HPA axis may play a crucial role in the development of SIBO because the stress response is closely linked to the gut microbiome.
Researchers have observed several interesting relationships between gut bacteria, stress, and the HPA axis. Gut bacteria can start a stress response by producing metabolites such as lipopolysaccharides (LPS), which provoke inflammation in the central nervous system. Gut microbes also produce hormones and neurotransmitters that are identical to those made in the human HPA axis and thus have the potential to alter HPA axis function. (2) On the flip side, hormones produced during times of stress adversely impact the composition of the gut microbiota and even enhance microbial growth and virulence.
Research suggests stress contributes to ongoing problems with SIBO and managing stress is essential for restoring gut health over the long-term.
Given the complicated relationship between stress and the gut microbiota, infection is only one piece of the SIBO treatment puzzle; chronic HPA axis activation and stress must also be addressed. Gut microbial imbalances and stress will tend to perpetuate each other in a vicious cycle, promoting recurrent SIBO, unless steps are taken to resolve both of these triggers. (3)
How Does Stress Promote SIBO?
Stress and HPA axis dysfunction contribute to SIBO through several mechanisms, including the reduction of gastric acid production, impairment of GI motility and gut mucosal immunity, enhanced bacterial growth and virulence, and the formation of biofilm.
Stress Reduces Gastric Acid Production
Gastric acid produced in the stomach serves the important purpose of killing ingested bacteria before they can enter the small intestine. The HPA axis tightly controls gastric acid production. Stress, and subsequent HPA axis dysfunction, significantly inhibit gastric acid secretion. (4, 5) In hunter–gatherer times, this adaptation would have been beneficial; if you were under acute stress being chased by a lion on the African savanna, you wouldn’t want your body to waste precious energy making gastric acid. However, in our modern-day world characterized by 24/7 stress, lowered gastric acid production may become a chronic condition. A chronic insufficiency of gastric acid allows a larger quantity of ingested bacteria to pass through the stomach unchallenged and enter the small intestine, where they can proliferate. Over time, too much bacteria entering the small intestine may promote the development of SIBO.
Stress Impairs GI Motility
The migrating motor complex (MMC), a pattern of electromechanical activity that sweeps through the intestine during periods between meals, regulates the movement of food through the GI tract. An absent or impaired MMC promotes the development of SIBO by causing food to stagnate in the small intestine, where it creates a breeding ground for bacterial overgrowth. Stress directly inhibits the migrating motor complex. (6) The relationship between stress, the MMC, and digestion was first observed in the early 19th century by William Beaumont, a former surgeon in the U.S. Army who later became known as the “Father of Gastric Physiology.” He noticed that “fear, anger, or whatever depresses or disturbs the nervous system” was associated with the suppression of GI motility and impaired digestion. (7) We now know that stress-induced inhibition of the MMC is mediated by corticotropin-releasing factor (CRF), a hormone central to the HPA axis. Once released by the hypothalamus, CRF binds to receptors in the brain, altering neurotransmission that governs the MMC. (8)
Stress also impairs GI motility by provoking blood sugar swings. High cortisol resulting from chronic stress causes blood sugar levels to fluctuate; these fluctuations promote frequent hunger and snacking throughout the day. Constant eating reduces the amount of time between meals, the period during which the MMC is most active, thus impairing gastrointestinal motility.
Stress Reduces Gut Mucosal Immunity
Secretory IgA (sIgA) is an immunoglobulin that helps to maintain immune function on mucosal membranes, including those of the GI tract. Stress decreases sIgA, a situation that may increase the risk of bacterial overgrowth in the intestine. (9)
Stress Enhances Bacterial Growth
Fascinatingly, stress hormones favor the growth of pathogenic bacteria. Catecholamines, which include epinephrine and norepinephrine, enhance bacterial attachment to host tissues and affect the growth and virulence of bacteria. (10) Stress also enhances general susceptibility to infection. (11) These findings represent another important link between stress and the risk of SIBO.
Stress May Promote Biofilm Formation
Biofilm, a community of microorganisms that share nutrients and DNA and undergo changes to evade the immune system, plays an important role in gut infections such as SIBO. Biofilm protects bacteria from antimicrobial treatments, resulting in extremely stubborn infection. Interestingly, stress response mediators, including cortisol and catecholamines, promote biofilm formation by helping pathogenic bacteria access nutrients they need to survive. (12, 13, 14) This is just one more fascinating example of how stress supports the best interests of bacteria in our bodies while degrading our health.
Stress Management in the Treatment of SIBO
Stress management should be a significant part of any treatment plan for eradicating SIBO. The following list includes strategies that help normalize HPA axis activity and reduce stress, with the ultimate goal of restoring gut health.
Space meals apart and fast overnight. Fasting between meals activates the MMC, which needs to be functional to prevent and reverse SIBO. Encourage your patients to space their meals at least four to five hours apart to allow the MMC to kick in. Ideally, your patients should also fast for at least 12 hours overnight. Intermittent fasting, where the patient compresses food intake into an eight-hour window and fasts for 16 hours each day, can be even more effective.
Find ways to reduce stress every day. I have previously written about the importance of stress reduction in the context of our overall health here and here. Here are a few of my favorite tips for reducing stress that you can pass on to your clients and patients:
- Learn to say “no.” Know and respect your limits and don’t take on more commitments than you can realistically handle.
- Avoid stressful people. People who continuously stir up drama drain our stress reserves; limit your time with these individuals or avoid them entirely, if possible.
- Turn off the news or limit your exposure to it. You can still be well-informed without continually feeding your brain stress-inducing information from the media.
- Let go of pointless arguments. While discussion and debate have their place, engaging in arguments is also a massive tax on our time and energy. Many arguments only serve to entrench peoples’ worldviews further. Learn to let go and move on.
- Edit your to-do list. Consider what tasks on your list are most important, and drop less important tasks to the bottom of the list.
Practice meditation or yoga and spend time in nature. These practices reduce HPA axis activation, helping to correct the adverse downstream effects of stress on GI motility, gastric acid secretion, gut mucosal immunity, and bacterial growth.
Measure and learn to regulate heart rate variability. Heart rate variability (HRV) is an objective indicator of the stress response. A high HRV is considered a good indicator of a balanced HPA axis. Your patients can measure their own HRV at home using systems such as Heartmath Inner Balance or BioForce HRV.
Consider methods of “neural retraining,” such as Dynamic Neural Retraining System, Gupta Amygdala Retraining, and Somatic Experiencing. These programs and approaches address deeply entrenched patterns in the brain and nervous system that may persist even after the initial trigger is no longer present, resulting in a more balanced HPA axis.
Try visceral manipulation or massage. Bodywork helps reduce stress and can even enhance GI motility.
Stimulate the migrating motor complex. The MMC needs to be in working order to treat SIBO successfully. Both pharmaceutical and over-the-counter options are available for stimulating the MMC. These include low-dose erythromycin, low-dose naltrexone, Iberogast, and MotilPro.
These treatments are powerful strategies for addressing stress as it relates to SIBO. When combined with antimicrobial treatments and dietary changes, these therapies have the potential to reverse stubborn cases of SIBO.