The Fibromyalgia-Gut Connection: Why Your Digestion Matters
The Latest Research (2024-2025)
Recent studies have dramatically advanced our understanding of the gut-fibromyalgia connection. A 2024 study published in a leading gastroenterology journal analyzed the microbiomes of hundreds of fibromyalgia patients and identified specific bacterial species consistently depleted or overabundant in patients compared to controls.
The research found that certain beneficial bacteria—particularly those that produce short-chain fatty acids like butyrate—were significantly reduced in fibromyalgia patients. These short-chain fatty acids are crucial for gut barrier function, immune regulation, and even pain modulation. Their deficiency could contribute to both gut symptoms and systemic fibromyalgia symptoms.
The Serotonin Connection
A 2025 study revealed another crucial piece of the puzzle: gut bacteria produce and influence serotonin levels. About 90% of your body's serotonin is produced in the gut, not the brain. This serotonin affects mood, pain perception, sleep, and gut motility.
Fibromyalgia patients often have dysregulated serotonin systems. The research suggests that altered gut bacteria may contribute to this serotonin dysfunction, affecting both gut symptoms (altered motility causing constipation or diarrhea) and fibromyalgia symptoms (mood problems, pain amplification, sleep disturbances).
Small Intestinal Bacterial Overgrowth (SIBO)
Multiple studies have found elevated rates of SIBO in fibromyalgia patients. SIBO occurs when bacteria overgrow in the small intestine where they don't belong. This causes bloating, pain, and malabsorption. More importantly, SIBO triggers systemic inflammation that can worsen fibromyalgia symptoms throughout the body.
Some studies report that treating SIBO in fibromyalgia patients—typically with antibiotics or herbal antimicrobials—improves not just digestive symptoms but also overall pain, fatigue, and quality of life. This suggests SIBO may be a treatable contributing factor to fibromyalgia severity in some patients.
Food Sensitivities and Inflammation
Many fibromyalgia patients report that certain foods trigger flares. Common culprits include gluten, dairy, sugar, and processed foods. While true food allergies are relatively rare, food sensitivities and intolerances appear common in fibromyalgia.
The mechanism likely involves increased intestinal permeability allowing partially digested food proteins to trigger immune responses. These immune responses don't just cause gut symptoms—they release inflammatory chemicals that amplify pain throughout the body and contribute to fatigue and cognitive dysfunction.
Research on elimination diets shows that removing triggering foods can significantly improve fibromyalgia symptoms in responsive patients. The challenge is identifying which foods are problematic, as this varies considerably between individuals.