The following article is part of conference coverage from the 2019 American Association of Nurse Practitioners Annual Meeting (AANP 2019) in Indianapolis, Indiana. Clinical Advisor’s staff will be reporting breaking news associated with research conducted by leading nurse practitioners. Check back for the latest news from AANP 2019.


Patients with an imbalanced microbiome may have increased pain and mood symptoms, and regulating the gut with probiotics and a modified diet may reduce these symptoms, according to research presented at the 2019 American Association of Nurse Practitioners (AANP) Annual Meeting, held June 18-23 in Indianapolis, Indiana.

Theresa Mallick-Searle, MS, ANP-BC, from the Division of Pain Medicine at Stanford Health Care, explored the prevalent role that the microbiome plays in pain and mood by describing how the gut is related to the brain.

The microbiome is made up of a collection of microorganisms that inhabit the alimentary canal. The microbiome functions best when there is a balance of both good and pathogenic bacteria. When the microbiome experiences an imbalance of microorganisms, autoimmune diseases such as diabetes, rheumatoid arthritis, muscular dystrophy, multiple sclerosis, and fibromyalgia may develop. An imbalance in the microbiome can occur because of overuse of antibiotics, which may cause an overgrowth of pathogenic bacteria and yeast. A fully functioning microbiome may never develop in infants who are not born vaginally or who are not breastfed.

The gut-brain axis provides an advanced understanding of the relationship between the microbiome and symptoms of pain and mood. Microbes that directly improve mood, or psychobiotics, are major players in the gut-brain axis. These microbiota communicate with the brain using neurotransmitters through the vagus nerve and using cytokines and hormones such as cortisol in the bloodstream.

A healthy gut has an intestinal lining comprised of a mucus layer, an epithelial layer, and a lamina propria layer. The lining prevents the entry of toxins, antigens, and pathogenic microorganisms and the loss of water, electrolytes, and nutrients. Prebiotic nutrients, plant-derived proteins, vitamins, probiotics, and polyunsaturated fats regulate intestinal permeability and maintain a healthy gut.

A dysbiotic gut allows pathogens to pass through, resulting in inflammation in the brain and gut. Dysbiosis also increases the immune response to food particles in the bloodstream, increasing the risk for food allergies. Pathogens such as Helicobacter pylori, Salmonella sp, and rotavirus; processed foods and gluten; and drugs such as proton pump inhibitors and nonsteroidal anti-inflammatory drugs increase intestinal permeability.

A study conducted by Shiro et al in 2017 sought to determine whether stool consistency predicted perception of pain. Patients reported stool form, demographic information, constipation, pain sensation, and their psychological states. Results from the study found that higher pain sensitivity and anxiety correlated with looser, more watery stool, which is a hallmark of a dysbiotic gut.  

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For patients with dysbiosis, a modified diet high in fish and olive oil, green tea, fruits, and vegetables may aid in gut regulation as these foods have anti-inflammatory effects. Saturated fats, dairy products, and gluten should be avoided as these foods have pro-inflammatory effects. A study presented at the American Association of Neurology 70th Annual Meeting found that a diet low in gluten may reduce the risk for peripheral neuropathic pain in patients with gluten neuropathy. An additional study conducted by Bunner et al in 2014 found that a low-fat, plant-based diet was effective in reducing migraine severity and frequency.

“Microbiota is diverse and has a definite effect on health, wellness, and pain,” Dr Mallick-Searle concluded. “Practical ways of modulating the microbiota include consuming low-allergenic, low-inflammatory, low-fat diets; instead, patients should consume diets high in fiber and whole grains.”

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Mallick-Searle T. The microbiome: pain and mood. Presented at: 2019 American Association of Nurse Practitioners (AANP) Annual Meeting; June 18-23; Indianapolis, IN.