Vitamin K supplementation in rheumatological diseases, except osteoporosis: a narrative review with systematic search

Abstract

Introduction: Vitamin K (VK) supplementation has been studied extensively in osteoporosis; however, its potential role in other rheumatic disorders remains underexplored. This systematic search strategy reviewed the evidence on VK supplementation in rheumatic diseases beyond osteoporosis.

Methods: A comprehensive search of PubMed/MEDLINE, Embase, and SciELO databases was conducted for studies published between 1966 and May 2024 evaluating VK supplementation in rheumatic diseases. Eligible studies included clinical trials and observational studies in adult patients diagnosed with rheumatic disorders, excluding osteoporosis.

Results: Ten studies comprising a total of 1,058 participants were included, including eight on rheumatoid arthritis (RA) and two on osteoarthritis (OA). Participants’ mean age ranged from 37.9 ± 8.2 to 68 ± 5.5 years, with female predominance (57.5–100%). VK dosages ranged from 20 µg to 45 mg/day, and follow-up periods ranged from two to 36 months. In RA, supplementation was associated with reductions in inflammatory and disease activity markers, including C-reactive protein (CRP), Disease Activity Score in 28 joints (DAS28), interleukin-6, and matrix metalloproteinase levels in several studies, although neutral results were also reported. In OA, improvements in pain, CRP, and joint space narrowing were reported mainly in patients who achieved adequate VK status or in studies using multi-ingredient supplements containing VK. Adverse events were rare and mild, including one case (1.5%) of heartburn.

Conclusion: VK supplementation may exert modest anti-inflammatory effects in RA and potential structural benefits in OA, but the available evidence is heterogeneous and limited by small sample sizes, short follow-up, confounding interventions, and the absence of recent large-scale randomized controlled trials.