Objective: Excess generation of reactive oxygen species in damaged joints accelerates inflammatory responses in RA (rheumatoid arthritis) patients. The complementary effects of dietary antioxidant supplementation on the blood level of inflammatory mediators and the severity of the disease in RA patients were evaluated.
Study design and settings: The study was conducted as a randomized, placebo-controlled, double-blind, three-treatment cross-over design trial. The participants visited the hospital as outpatients.
Subjects: Twenty patients meeting the 1987 criteria for the classification of rheumatoid arthritis completed the study.
Interventions: The subjects were randomized in three groups to receive one of following supplementation; quercetin+vitamin C (166 mg+133 mg/capsule), alpha-lipoic acid (300 mg/capsule) or placebo for 4 weeks (3 capsules/day). Each treatment period consisted of 4 weeks with 2 weeks of wash-out period before the subject starts next supplementation.
Outcome parameters: Serum levels of tumor necrosis factor-alpha(TNF-alpha), interleukin-1beta(IL-1beta), interleukin -6(IL-6), and C-reactive protein (CRP) were measured. The severity of disease was evaluated using Korean Health Assessment Questionnaire(KHAQ) and Visual Analogue Scale(VAS). Nutrient intake was measured at baseline and at the end of each intervention period.
Results: The mean energy and nutrient intakes remained constant during study period. No significant differences were found in the serum concentrations of pro-inflammatory cytokines and CRP between treatments. The scores of disease severity measurements were not significantly different between treatments, although quercetin supplementation had a tendency to reduce VAS.
Conclusions: Dietary supplementation of antioxidants at 900 mg/day for 4 weeks did not change the blood biomarkers of inflammation and disease severity of RA patients under conventional medical treatments. Further considerations for dose-response relationships, duration of supplementation, and susceptible biomarkers are required.