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Evidence-Based Supplement Research
Evidence-Based Supplement Research

Vitamin D and Improved Health-related Quality of Life

Research synthesisLow evidenceSmall effect3 studies · 1 beneficial · 2 neutral · 0 harmful

Across 3 studies, 1 reported a beneficial small effect on health-related quality of life, while 2 higher-quality studies (a meta-analysis and an RCT) found neutral effects. The predominant effect size is small. Most evidence comes from clinical populations (e.g., postmenopausal breast cancer, ulcerative colitis, Hashimoto's thyroiditis), and the only study reporting duration (28 days) showed no benefit over placebo.

  • Studied populations: clinical populations: postmenopausal women with hormone receptor-positive breast cancer, patients with mild-to-moderate ulcerative colitis, and patients with Hashimoto's thyroiditis

Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. Many of the included studies did not reach statistical significance — effect may be smaller than the predominant direction suggests. The single beneficial study is a low-quality review (evidence score 1), while the higher-quality studies (meta-analysis and RCT) found no effect. No consistent dose or form data were reported.

Generated Jul 13, 2026
Time to effect
Median: 4 weeks · IQR 4 weeks4 weeks · Range 4 weeks4 weeks — Reported in 1 of 3 studies
3 of 3 papers
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