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Evidence-Based Supplement Research
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Vitamin D2 and Increased 25-hydroxyvitamin D Level

Research synthesisModerate evidenceLarge effect3 studies · 3 beneficial · 0 neutral · 0 harmful

Across 3 studies, all reported beneficial effects of vitamin D2 on increasing 25-hydroxyvitamin D levels, with large effects in 2 randomized controlled trials and moderate effects in 1 meta-analysis. The median study duration was 57 days (approximately 8 weeks), suggesting effects are typically observed within a similar timeframe. Most-studied populations were clinical (patients with chronic intestinal failure and vitamin D deficiency) and health care workers, with the highest-evidence study using a high intramuscular dose of 600,000 units every two weeks for 10 weeks.

  • Effective dose range: 600,000 units intramuscularly every two weeks (84-day study); other studies did not report dose
  • Studied populations: adults with chronic intestinal failure and vitamin D deficiency, health care workers

Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. Available evidence is overwhelmingly positive — clinical literature in this area is subject to publication bias (null-result studies are less likely to be published or indexed). The meta-analysis noted that vitamin D3 was superior to vitamin D2 in raising total 25-hydroxyvitamin D concentrations, suggesting that the form may influence effect magnitude.

Generated Jul 13, 2026
Doses used in studies
  • units/week: 300,000 (median 300,000, IQR 300,000–300,000) — 1 study
Time to effect
Median: 8.1 weeks · IQR 6.2 weeks–10.1 weeks · Range 4.3 weeks–2.8 months — Reported in 2 of 3 studies
Safety in these studies
3 of 3 papers
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