Vitamin K1 and Rheumatoid Arthritis: What the Study Shows

clinical-trial PMID: 26156560

Vitamin K1 and Rheumatoid Arthritis: What the Study Shows

Quick Summary:
A small clinical trial gave 64 women with rheumatoid arthritis (RA) a daily vitamin K1 supplement (10 mg) for 8 weeks. The researchers measured joint‑damage markers and an auto‑antibody called rheumatoid factor (RF). Vitamin K1 did not meaningfully lower joint‑damage markers or improve overall disease activity, and the drop in RF was not strong enough to be considered a real benefit.

What The Research Found

Joint‑damage marker (MMP‑3) stayed the same.
The level of a protein that helps break down joint tissue (matrix metalloproteinase‑3) did not change with vitamin K1.
Rheumatoid factor fell a little, but not enough to matter.
Inside the vitamin K1 group, RF levels dropped slightly, but when compared to the placebo group the difference disappeared.
Overall disease activity didn’t improve.
Scores that doctors use to rate RA severity (DAS‑28) were unchanged after the supplement.

Bottom line: In this short‑term study, vitamin K1 did not provide a clear benefit for women with RA.

Study Details

Who was studied:
64 adult women diagnosed with rheumatoid arthritis.
All met the trial’s health and medication criteria.
How long:
8 weeks (about two months).
What they took:
One capsule containing 10 mg of vitamin K1 (phylloquinone) each day, or a matching placebo capsule.
What was measured:
Blood levels of MMP‑3 (a marker of joint breakdown).
Blood levels of rheumatoid factor (RF) (an auto‑antibody linked to RA).
DAS‑28 score, a standard rating of RA disease activity.

What This Means For You

Don’t count on vitamin K1 to control RA symptoms.
The study suggests that a short‑term, high‑dose vitamin K1 supplement won’t reduce joint damage or overall disease activity.
If you already take vitamin K1 for other reasons, keep using it.
Vitamin K1 is essential for blood clotting and bone health, but this research does not support using it as a stand‑alone RA treatment.
Focus on proven RA strategies.
Continue with doctor‑prescribed medicines, physical therapy, balanced diet, and regular exercise—these have stronger evidence for managing RA.
Talk to your rheumatologist before adding new supplements.
Your doctor can help you decide if a vitamin K1 supplement fits into your overall treatment plan.

Study Limitations

Only women were included. Results may not apply to men with RA.
Eight weeks may be too short. Longer studies might show different effects.
Only two biomarkers were checked. Other inflammation markers (like CRP) were not measured.
Dose may not be optimal. 10 mg is higher than typical dietary intake, but we don’t know the best amount for RA.
No data on supplement adherence or baseline vitamin K status. How well participants took the pills and their starting vitamin K levels could influence outcomes.

If you’re looking for ways to support joint health, consider a balanced diet rich in leafy greens (which naturally contain vitamin K), stay active, and follow your healthcare provider’s guidance.

Key Findings

The study found that 10 mg/day of vitamin K1 (phylloquinone) for 8 weeks did not significantly reduce joint destruction biomarkers (matrix metalloproteinase-3, MMP-3) or improve disease activity scores (DAS-28) in women with rheumatoid arthritis (RA). While rheumatoid factor (RF) levels decreased within the vitamin K1 group (p = 0.041), this effect vanished after adjusting for confounders (p > 0.05), suggesting no robust intergroup difference.

Study Design

This was a randomized, double-blind, placebo-controlled clinical trial conducted in 2016. The sample included 64 women with RA who met eligibility criteria, divided into intervention (n=32) and control (n=32) groups. Assessments occurred at baseline and post-intervention (8 weeks), measuring clinical status (DAS-28), serum MMP-3, and RF levels.

Dosage & Administration

Participants received 10 mg/day of phylloquinone (vitamin K1) or a placebo via capsule form for 8 weeks. The placebo matched the appearance of the vitamin K1 capsules to maintain blinding.

Results & Efficacy

MMP-3: No significant changes from baseline in either the vitamin K1 or placebo group (p > 0.05).
Rheumatoid Factor (RF):
Within the vitamin K1 group, RF decreased significantly (p = 0.041).
After adjusting for confounders (e.g., age, disease duration), intergroup differences were not statistically significant (p > 0.05).
DAS-28 Scores: No improvements in disease activity observed between groups (p > 0.05).

Limitations

Sample Specificity: Limited to women, so results may not generalize to men.
Short Duration: 8 weeks might be insufficient to detect long-term effects on joint health or immune markers.
Biomarker Scope: Focused only on MMP-3 and RF; other inflammatory or bone metabolism markers (e.g., CRP, IL-6) were not assessed.
Dose Consideration: 10 mg/day is higher than typical dietary intake but may not be optimal for RA-specific outcomes.
Compliance & Baseline Variability: No details provided on adherence rates or baseline vitamin K status, which could influence efficacy.

Clinical Relevance

For RA patients, this study suggests that vitamin K1 supplementation at 10 mg/day for 8 weeks does not meaningfully alter joint destruction biomarkers or disease activity. While the within-group RF reduction is intriguing, the lack of intergroup significance weakens its clinical applicability. Practically, supplement users should not expect vitamin K1 to improve RA symptoms based on this trial. Future research could explore longer durations, different doses, or combined interventions targeting multiple pathways.

Takeaway: This trial does not support vitamin K1 as a standalone therapy for RA, though it highlights the need for larger, more diverse studies to clarify its potential role in autoimmune conditions.

Vitamin K1 and Rheumatoid Arthritis: What the Study Shows