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Evidence-Based Supplement Research
Evidence-Based Supplement Research
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Vitamin D and Reduced C-Reactive Protein Levels

Research synthesisModerate evidenceModerate effect7 studies · 4 beneficial · 3 neutral · 0 harmful

Across 7 studies, 4 reported beneficial moderate-sized effects of vitamin D supplementation on reducing C-reactive protein levels, while 3 found no significant effect. Effects were predominantly moderate in studies showing benefit. Most studies focused on clinical populations (obese/overweight, diabetes/prediabetes, tuberculosis), and the median study duration was 118 days, suggesting effects typically observed after several months.

  • Studied populations: obese/overweight individuals, patients with diabetes or prediabetes, extrapulmonary tuberculosis patients

Caveats: Three of seven studies found no significant effect — benefit may not generalize. Many positive studies combined vitamin D with other supplements (magnesium, vitamin E, N-acetylcysteine), complicating interpretation of vitamin D's independent effect. Dosing varied and was not consistently reported.

Generated Jul 11, 2026
Doses used in studies
  • IU/day: 1,000 (median 1,000, IQR 1,000–1,000) — 2 studies
Time to effect
Median: 3.9 months · IQR 2.9 months–5 months · Range 8 weeks–6 months — Reported in 2 of 7 studies
Safety in these studies
7 of 7 papers
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