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Evidence-Based Supplement Research
Evidence-Based Supplement Research
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Vitamin D and Improved Quality of Life

Research synthesisModerate evidenceSmall effect8 studies · 7 beneficial · 1 neutral · 0 harmful

Across 8 studies, 7 reported beneficial effects on quality of life, with effect sizes ranging from small to large. The most consistent evidence comes from clinical populations, particularly patients with chronic urticaria and fibromyalgia, where a moderate effect was observed in larger meta-analyses. Dosing was reported in one systematic review as 4000 IU/day or 60000 IU/week, but study durations and forms were not consistently noted.

  • Effective dose range: 4000 IU/day or 60000 IU/week
  • Studied populations: patients with chronic urticaria, fibromyalgia, Alzheimer's disease, breast cancer, and gastrointestinal surgery patients

Caveats: 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). Most studies were in clinical populations with specific conditions, so benefit may not generalize to healthy adults. The neutral study in breast cancer patients highlights that effects may not be universal across all populations.

Generated Jul 14, 2026
Doses used in studies
  • IU/day: 4,000–60,000 (median 32,000, IQR 4,000–60,000) — 1 study
Safety in these studies
8 of 8 papers
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