Conclusion: Vitamin D supplementation alone was not associated with all cause mortality in adults compared with placebo or no treatment. Vitamin D supplementation reduced the risk of cancer death by 16%. Additional large clinical studies are needed to determine whether vitamin D3 supplementation is associated with lower all cause mortality.
PubMed 31405892 ↗Vitamin D Supplementation
People mainly take Vitamin D Supplementation for energy, focus, immunity. Based on 3 first-hand reports and 1,028 meta-analyses & systematic reviews in the medical literature. Ranked #1301 of 3,539 overall.
Of reports that state an outcome, 67% are positive.
What Vitamin D Supplementation does, according to users
Of the people who reported each effect, the share who said it got better.
What the research says
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: The body of evidence contributing to these analyses was assessed as being of high quality.Conclusions Vitamin D supplementation was safe and it protected against acute respiratory tract infection overall. Patients who were very vitamin D deficient and those not receiving bolus doses experienced the most benefit.Systematic review registration PROSPERO CRD42014013953.
PubMed 28202713 ↗Conclusion: The results regarding the effect of VDS on sleep-related impairment, difficulty, and disorders, as well as sleepiness and restless legs syndrome, were not unanimous. Conclusions: VDS is promising in improving sleep quality; however, its effect on sleep quantity and disorders needs to be further investigated.
PubMed 35268051 ↗Conclusion: Dairy products fortified with calcium and vitamin D have a favorable effect on bone mineral density. Combined calcium and vitamin D supplementation could prevent osteoporosis hip fracture in postmenopausal women.
PubMed 33237064 ↗Dosage people report
As stated by users — not a recommendation. Follow the label or your doctor.
Reported side effects
How often each side effect came up across all reports.
What users say
First-hand experiences, quoted verbatim. We show one positive and one negative where both exist.
“deficiencies in a lot of trace minerals, b12, D, iron, and other things...my mental acuity has skyrocketed.”
Top discussions (3)
Other options for energy
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 3, 2026. How we rate