Vitamin K1 supplementation did not alter inflammatory markers and clinical status in patients with rheumatoid arthritis

Background: Rheumatoid arthritis (RA) is an inflammatory disorder in which the disease severity might be decreased by anti-inflammatory agents. There are several lines of evidence which support anti-inflammatory effects of vitamin K. The aim of this study was to examine whether vitamin K is a useful strategy for reducing inflammation in RA subjects. Materials and methods: In this double-blind placebo controlled trial, 58 patients with definitive RA were randomly allocated into two groups to receive vitamin K1 as phylloquinone [10 mg/day] or placebo pills for 8 weeks. Clinical status using disease activity score-28 (DAS-28) and serum concentrations of some inflammatory markers (IL-6, hs-CRP, TNFα) were assessed at baseline and at the end of intervention. Results: There were no significant differences between the two groups regarding any of the baseline characteristics. In the vitamin K1 group, a 27 % decrease in serum levels of IL-6 (P = 0.006) and a 13 % decrease in DAS- 28 (P = 0.041) were observed. However, after adjusting for relevant confounders, i. e.; duration of RA, intake of folic acid supplements, energy intake, weight and baseline values of each variable, by comparing the two groups, we found no significant reduction in these markers. Conclusion: Vitamin K1 supplementation at 10 mg/day for 8 weeks had no significant effects on blood biomarkers of inflammation and disease severity of patients with rheumatoid arthritis compared with the placebo group.