Results of a prospective experimental study revealed that patients with fibromyalgia had a similar prevalence of nonceliac gluten sensitivity as the general population. These findings were published in Rheumatology.
Patients (N=142) with fibromyalgia were recruited between 2018 and 2019 at the Hospital Universitari Vall d’Hebron in Barcelona, Spain. All study participants followed a strict gluten-free diet intervention for 6 weeks. Response to the gluten-free diet was defined as a greater than 30% reduction in 1 of 3 main intestinal symptoms and at least 1 extraintestinal symptom with no worsening of other symptoms for at least 3 weeks. Responders to the gluten-free diet were randomly assigned to undergo a single-blind gluten challenge involving gluten 10 g or placebo sachets. Evaluation was conducted using the nonceliac gluten sensitivity Salerno criteria.
Mean age of the patient population was 52.02 (standard deviation [SD], 8.02) years, 95.07% were women, mean BMI was 27.16 (SD, 4.74) kg/m2, 55.63% were self-diagnosed as lactose intolerant, 98.59% had intestinal symptoms, and mean visual analogue score (VAS) for pain was 7.78 (SD, 0.81) cm.
After 6 weeks on the gluten-free diet, decreases in the following parameters were noted: average number of total symptoms (-2.77; SD, 3.17), intestinal symptoms (-2.58; SD, 2.89), extraintestinal symptoms (-0.23; 0.54), VAS pain score (-0.57 cm; SD, 1.01), VAS fatigue score (-0.83 cm; SD, 1.07), and Fibromyalgia Impact Questionnaire (FIQ) score (-3.87; SD, 6.56). The 36-item short form (SF-36) physical function score increased by 1.49 (SD, 4.03).
A total of 31 (21.8%) patients responded to the gluten-free diet, as demonstrated by improvement in intestinal symptoms. Characteristics at baseline associated with response to the gluten-free diet included diarrhea (odds ratio [OR], 29.55; 95% CI, 3.13-278.62; P =.0031) and intraepilelial lymphocytosis (OR, 3.34; 95% CI, 1.05-10.63; P =.0406). Patients with low levels of anxiety as determined by the Hospital Anxiety and Depression Scale (HADS) tended to be less likely to respond to the gluten-free diet (OR, 0.80; 95% CI, 0.69-0.94; P =.051).
After the 6-week gluten-free diet intervention, no significant improvements in extraintestinal symptoms or physical functioning were observed.
Among the responders, 23 patients who were challenged with gluten did not discriminate between gluten and placebo, thereby not meeting the criteria for nonceliac gluten sensitivity.
This study may have included some selection bias, as patients were recruited at a specialized hospital unit and likely had more severe fibromyalgia.
Study authors concluded, “According to the results obtained in this study, a [gluten-free diet] cannot be systematically recommended to all patients with [f]ibromyalgia, although it could be evaluated in those with diarrhea or intraepithelial lymphocytosis to evaluate if there are improvements in their intestinal symptoms.”
Almirall M, Casellas F, Dot J, de Torres I, Segurola H, Marshal SS. Prevalence of nonceliac gluten sensitivity and assessment of the response to gluten-free diet in a cohort of patients with fibromyalgia. Rheumatology. Published online July 28, 2022. doi:10.1093/rheumatology/keac434