Gluten-Free Diet Improves Fibromyalgia Symptoms

Patients with fibromyalgia treated with a gluten-free diet had improved symptom severity and widespread pain index, according to a study published in The Italian Journal of Rheumatology.¹ Results were confirmed using a rechallenge of this diet followed by a period of a nonrestricted gluten-containing diet.

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“In a nonnegligible percentage of patients, fibromyalgia is associated with abdominal symptoms characterized by pain and diarrhea, attributable to irritable bowel syndrome (IBS),” wrote a team of Italian investigators. “Some studies show that in IBS patients, there is an overlap with celiac disease (CD) or non-celiac hypersensitivity to gluten (NCGS), and a gluten-free diet can improve the symptoms of IBS.”

Previous research has demonstrated positive improvements in pain and function in patients with fibromyalgia following a hypocaloric diet, a raw vegetarian diet, and a low FODMap diet. However, the gluten-free diet has shown conflicting results. Certain research has only recommended it for use in patients with IBS, fibromyalgia, and lymphocytic enteritis. Thus far, no studies have evaluated modifications observed in the symptom severity scale and widespread pain index in this patient population following a gluten-free diet.²

Participants included 20 postmenopausal women with fibromyalgia refractory to pharmacological treatment and no history of celiac disease enrolled in 2016 at the Department of Internal Medicine and Rheumatology, PO S Spirito-Nuovo Regina Margherita Hospital, in Rome, Italy. Conventional pharmacological therapy was defined as treatment with nonsteroidal anti-inflammatory drugs (NSAIDs), duloxetine, or pregabalin. The gluten-free diet was followed for a total of 6 months, followed by 3 months of a nonrestricted gluten-containing diet, and then an additional 6 months of the gluten-free protocol. At each visit, symptom severity and the widespread pain index was assessed.

The mean age of patients was 53.9 years and disease duration was 2.1±1.5 years prior to study initiation. Although subjects indicated vague gastrointestinal symptoms, none were diagnosed with IBS. At the 6-month mark, a significant reduction was reported in both the widespread pain index (10.3±1.8 vs 7.7±1.4; P <.0001) and the symptom severity scale (6.4±1.8 vs 4.15±1.6; P = .0002) in patients undergoing a gluten-free diet. The percentage reduction of the widespread pain index after 6 months was -24%±9% and the symptom severity scale was reduced by -36%±21%.

The reintroduction of gluten demonstrated a statically significant rise in symptom severity and widespread pain index, in addition to a change in the pain index and symptom severity (21%±13% and 74%±90%, respectively). However, the rechallenge of the gluten-free diet showed a significant improvement in absolute widespread pain index and symptom severity (-24%±7% and -36%±11%, respectively).

Investigators noted limitations including not measuring biochemical parameters of inflammation and not randomizing patients to a gluten-free diet or controls. However, a strength was the rechallenge of the diet as each participant was a control for themselves. Additional limitations were the small sample size, the lack of a calculation of the sample size prior to the study initiation, and a lack of standardized parameters for determining patient adherence to the diet.

“Dietary intervention might be a useful new intervention strategy for patients affected by fibromyalgia,” investigators concluded. “Additional double-blind controlled trials on large samples are needed to include gluten-free diets as a possible standard therapy for fibromyalgia and to clarify the exact mechanism that links gluten to fibromyalgia.”

References

1. ^{Bruzzese V, Marrese C, Scolieri P, Pepe J. Efficacy of a gluten-free diet in reducing the widespread pain index and symptom severity scale in patients affected by fibromyalgia. Reumatismo. 2023;75(3):10.4081/reumatismo.2023.1530. Published 2023 Sep 18. doi:10.4081/reumatismo.2023.1530}
2. ^{Volta U. Gluten-free diet in the management of patients with irritable bowel syndrome, fibromyalgia and lymphocytic enteritis. Arthritis Res Ther. 2014; 16: 505}