The aim of this study is to evaluate the impact of gluten-free diets on symptoms and inflammatory markers in individuals with previous diagnosis of fibromyalgia (FM), as well as to identify the presence of non-celiac gluten sensitivity (NCSG) in individuals with FM. Patients with FM diagnosis will be kept on a gluten-free diet for a 10 weeks. In the 7th week, they will receive placebo capsules for 7 days and after washout, capsules containing gluten for another 7 days. A questionnaire based on Salerno protocol will be applied to evaluate the presence of NCGS in the beginning, 8th week and 10 week.

Fibromyalgia (FM) is a chronic and widespread pain condition, usually accompanied by several associated symptoms such as fatigue, sleep disorder, headache, irritable bowel syndrome and mood disorders. Recent studies point to the possibility of gluten protein having a role in the development of FM symptoms in a subgroup of patients. Fourteen patients with FM diagnosis will be kept on a diet restrict in gluten-free foods for a period 10 weeks. At the 7th week they received rice protein isolate capsules (placebo) for 7 days, followed by a 3-day wash-out and a new challenge with capsules containing 8 g/day of gluten (corresponding to 6,3g gluten protein) for another 7 days. In the initial period, at 8th week (final of placebo period) and after challenge with gluten (10th week), blood will be collected for analysis of inflammatory markers. Questionnaires will be carried out to evaluate the quantity and severity of FM symptoms and the impact of FM on daily routine. Inflammatory markers (IL-1bera, IL-6 and IL-10) will be evaluated in the blood. In the challenger period (gluten or placebo) questionnaires will be carried out to evaluate the quantity and severity of symptoms related to fibromyalgia and the impact of fibromyalgia on a daily basis. In addition, a questionnaire based on Salerno protocol was applied to evaluate the presence of NCGS.

Inclusion Criteria:

• Women between 18 and 65 years of age with prior clinical diagnosis of FM, according to the American College of Rheumatology criteria of 2010

Exclusion Criteria:

• Subjects diagnosed with positive serology for celiac disease or allergy to wheat
• Subjects diagnosed with autoimmune diseases
• Subjects with diseases that are not part of the comorbidities associated with FM and t hat could influence the results of the study
• Pregnant or lactating women