People mainly take Vitamin D for mood, energy, sleep. Based on 1,505 first-hand reports and 3,251 meta-analyses & systematic reviews in the medical literature. Ranked #80 of 1,974 overall.
Of reports that state an outcome, 66% are positive.
Of the people who reported each effect, the share who said it got better.
Systematic reviews and meta-analyses from PubMed, with their published conclusions.
3+ meta-analyses or systematic reviews and 10+ randomized controlled trials in humans. The grade measures how much human research exists — read the conclusions below for what it found.
Conclusion: These results indicate that the prevalence of vitamin D deficiency was more elevated in obese subjects. The vitamin D deficiency was associated with obesity irrespective of age, latitude, cut-offs to define vitamin D deficiency and the Human Development Index of the study location.
PubMed 25688659 ↗Conclusion: No significant differences were found in PASI after 3, 6, and 12 months of supplementation. It is shown that 25(OH)D serum levels are significantly lower in psoriasis, but, although the granularity of RCT methodology may have influenced the pooled analysis, vitamin D supplementation did not seem to improve clinical manifestations.
PubMed 37571324 ↗Conclusion: Vitamin D deficiency and insufficiency are associated with miscarriage. Whether preconception treatment of vitamin D deficiency protects against pregnancy loss in women at risk of miscarriage remains unknown.
PubMed 35637024 ↗Conclusion: In adults with prediabetes, vitamin D was effective in decreasing risk for diabetes.
PubMed 36745886 ↗As stated by users — not a recommendation. Follow the label or your doctor.
How often each side effect came up across all reports.
Verbatim quotes, shortened only — each links to the original discussion.
“I micro-dose coffee, vitamin d, and lemon juice every morning”
“Supplements: Vitamin D, niacin, potassium, marine collagen.”
“Vitamin D - deficient”
“d3/k2”
“Within a month my allergies and asthma were basically gone. My depression was starting to lift.”
User data from public discussions; research from PubMed. Information only, not medical advice — talk to a doctor before starting, stopping or combining anything. Data updated October 2, 2026. How we rate