- Fractures (all types)No clear difference2% lower rate1 randomised trial2022 study ↗
- Hip fracturesNo clear difference1% higher rate1 randomised trial2022 study ↗
- Non-spine fracturesNo clear difference3% lower rate1 randomised trial2022 study ↗
supplement
Vitamin D3
Also known as Cholecalciferol
Fat-soluble vitamin synthesised in skin from UVB exposure and activated by the liver and kidneys; regulates calcium and phosphate absorption for bone health and modulates immune and mood pathways via vitamin D receptors.
Be careful if: pregnant, breastfeeding, some medical situations
Ask first if you take: blood-pressure medicines, statins
Upper limit: 100 micrograms per day (4,000 IU) — adults including pregnant and breastfeeding women and children aged 11 to 17 (NHS); NIH ODS gives a UL range of 25 to 100 micrograms depending on age
Suspect a side effect? Report it to the MHRA Yellow Card scheme ↗
5linked conditions
40linked studies
Evidence
What the research actually shows
We link to relevant studies and leave interpretation to you and your healthcare professional.
What studies found
The headline results, condition by condition
The large figures are what the studies reported for each thing they measured. Open a card for every result.
Colour keyReported a benefitNo clear benefitUnclearPossible harmAmber is for highlights, such as where the most research is. It never means a result was good.
- Depression symptomsNo clear difference0.01 points higher1 randomised trial2020 study ↗
- Risk of developing depressionNo clear difference3% lower rate1 randomised trial2020 study ↗
- Fatigue symptomsFell by 3.3 vs 0.8in the comparison group, unit not reported on the FAS scale1 randomised trial2016 study ↗
- People reporting less fatigue2.63 timesthe odds of the comparison group1 randomised trial2016 study ↗
Safety
Safety and considerations
What sources report about side effects, who should be careful, and medicines to ask about first.
Serious effects reported
| Reported effect | How often | Basis | Sources |
|---|---|---|---|
| Too much calcium in the blood (hypercalcaemia) from long-term excessive intake, which can weaken bones and damage the kidneys and the heart | unknown | Listed by NIH ODS fact sheets | Vitamin D (NIH ODS fact sheet, Health Professional edition; retrieved via Internet Archive snapshot 2026-10-09)NHS: Vitamin D (Vitamins and minerals) |
Be careful if you…
| Applies to | What sources say | Sources |
|---|---|---|
| pregnant | Pregnant women should not take more than 100 micrograms (4,000 IU) of vitamin D a day; 10 micrograms a day is enough for most people, and pregnant women are advised to consider a 10-microgram daily supplement (NHS). | NHS: Vitamin D (Vitamins and minerals) |
| breastfeeding | Breastfeeding women should not take more than 100 micrograms (4,000 IU) a day; a 10-microgram daily supplement is the general autumn/winter advice (NHS). | NHS: Vitamin D (Vitamins and minerals) |
| some medical situations | Some people have medical conditions that mean they may not be able to take as much as the general limits; if in doubt, consult a doctor, and follow a doctor's recommended amount if one has been given (NHS). | NHS: Vitamin D (Vitamins and minerals) |
Medicines to ask about
| Severity | Medicine | Sources |
|---|---|---|
| caution | blood-pressure medicines — NIH ODS lists thiazide diuretics, a type of blood-pressure medicine, among the medicines vitamin D supplements may interact with. | Vitamin D (NIH ODS fact sheet, Health Professional edition; retrieved via Internet Archive snapshot 2026-10-09) |
| listed | statins — NIH ODS lists statins among the medicines vitamin D supplements may interact with. | Vitamin D (NIH ODS fact sheet, Health Professional edition; retrieved via Internet Archive snapshot 2026-10-09) |
How much is too much
100 micrograms per day (4,000 IU) — adults including pregnant and breastfeeding women and children aged 11 to 17 (NHS); NIH ODS gives a UL range of 25 to 100 micrograms depending on age
Evidence analytics
Where the evidence is concentrated
Audited published research for Vitamin D3 by condition. Drill into a pair page for the full breakdown.
Vitamin D3: findings by condition
What this means: Bars count reported findings, not treatment effectiveness or certainty.
One study may report several findings or appear in more than one pairing. Counts do not show the size of an effect. Comparable numerical estimates are not established for this summary.
View the full data table
| Compound and condition | Findings (count) | Studies (count) | Reported results (finding counts) | How sure? |
|---|---|---|---|---|
| Bone Health | 3 | 1 | Benefit: 0; no benefit: 3; harm: 0; unclear: 0; not recorded / unrecognised: 0 | Not formally graded |
| Depression | 2 | 1 | Benefit: 0; no benefit: 2; harm: 0; unclear: 0; not recorded / unrecognised: 0 | Not formally graded |
| Fatigue | 2 | 1 | Benefit: 2; no benefit: 0; harm: 0; unclear: 0; not recorded / unrecognised: 0 | Not formally graded |
Suggested uses (unproven)
Where people report using it and what trials suggest
- Strong evidenceCorrection of deficiency / rickets & osteomalacia prevention
- Moderate evidenceBone health in older adults (with calcium, fracture risk)
- Moderate evidenceImmune support / respiratory infections in deficient people
Where the evidence is negative
Common claims the trials do not support
- Large trials (VITAL, ~26k participants) found no reduction in cardiovascular events or cancer in people who were not deficient.
- No overall mortality benefit from routine high-dose supplementation in the general population.
- Does not improve depression symptoms in adequately nourished people (meta-analyses null or marginal).
Fat-soluble vitamin essential for calcium absorption and bone health. Correction of deficiency is well established; most other proposed benefits have not survived large trials.
Evidence grades reflect study quality and consistency, not marketing claims.
40studies referenced
33journals
1998–2026publication range
Ordered by strength of evidence, then result direction.
01Vitamin D's Impact on Cancer Incidence and Mortality: A Systematic ReviewWimalawansa SJ · Nutrients · 2025PMID 40732958 ↗02Role of vitamin D as adjuvant therapy on multiple sclerosis: an updated systematic review and meta-analysis of randomized controlled trialsSerag I, et al. · European journal of medical research · 2025PMID 40797337 ↗03Population-based interventions for preventing falls and fall-related injuries in older peopleLewis SR, et al. · The Cochrane database of systematic reviews · 2024PMID 38180112 ↗04The effect of vitamin D supplementation on depression: a systematic review and dose-response meta-analysis of randomized controlled trialsGhaemi S, et al. · Psychological medicine · 2024PMID 39552387 ↗05The effect of vitamin D supplementation on depressive symptoms in adults: A systematic review and meta-analysis of randomized controlled trialsMikola T, et al. · Critical reviews in food science and nutrition · 2023PMID 35816192 ↗06What is the impact of daily oral supplementation of vitamin D3 (cholecalciferol) plus calcium on the incidence of hip fracture in older people? A systematic review and meta-analysisManoj P, et al. · International journal of older people nursing · 2023PMID 35842938 ↗Show all 40 studies
07Calcium and vitamin D for increasing bone mineral density in premenopausal womenMéndez-Sánchez L, et al. · The Cochrane database of systematic reviews · 2023PMID 36705288 ↗08Effect of Vitamin D Supplementation on Fatigue in Multiple Sclerosis: A Systematic Review and Meta-AnalysisLópez-Muñoz P, et al. · Nutrients · 2023PMID 37447189 ↗09Supplementation of vitamin D isolated or calcium-associated with bone remodeling and fracture risk in postmenopausal women without osteoporosis: A systematic review of randomized clinical trialsReis AR, et al. · Nutrition (Burbank, Los Angeles County, Calif.) · 2023PMID 37544189 ↗10Impact of vitamin D on cardiac structure and function in chronic kidney disease patients with hypovitaminosis D: a randomized controlled trial and meta-analysisBanerjee D, et al. · European heart journal. Cardiovascular pharmacotherapy · 2021PMID 31830258 ↗11Vitamin D supplementation to prevent acute respiratory infections: a systematic review and meta-analysis of aggregate data from randomised controlled trialsJolliffe DA, et al. · The lancet. Diabetes & endocrinology · 2021PMID 33798465 ↗12Relationship between vitamin D deficiency and both gestational and postpartum depressionRibamar A, et al. · Nutricion hospitalaria · 2020PMID 33155475 ↗13Vitamin D supplementation to prevent acute respiratory infections: individual participant data meta-analysisMartineau AR, et al. · Health technology assessment (Winchester, England) · 2019PMID 30675873 ↗14Efficacy and Safety of Vitamin D Supplementation in Patients With Systemic Lupus Erythematosus: A Meta-analysis of Randomized Controlled TrialsZheng R, et al. · The American journal of the medical sciences · 2019PMID 31331447 ↗15Vitamin D for the management of multiple sclerosisJagannath VA, et al. · The Cochrane database of systematic reviews · 2018PMID 30246874 ↗16Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant dataMartineau AR, et al. · BMJ (Clinical research ed.) · 2017PMID 28202713 ↗17Effect of Vitamin D3 Supplementation on Inflammatory Markers and Glycemic Measures among Overweight or Obese Adults: A Systematic Review of Randomized Controlled TrialsZuk A, et al. · PloS one · 2016PMID 27116227 ↗18Effects of vitamin D supplements on bone mineral density: a systematic review and meta-analysisReid IR, et al. · Lancet (London, England) · 2014PMID 24119980 ↗19Vitamin D supplementation and incidence of major depressive disorder - A randomized clinical trialAhl NM, et al. · Clinical nutrition (Edinburgh, Scotland) · 2026PMID 41506003 ↗20Effects of personalized vitamin D(3) on inflammation in colorectal cancer patients: a randomized trialGwenzi T, et al. · British journal of cancer · 2026PMID 41507560 ↗21The effects of Omega-3 fatty acids and vitamin D supplementation on the quality of life and blood inflammation markers in newly diagnosed breast cancer women: An open-labelled randomised controlled trialAlmassri HF, et al. · Clinical nutrition ESPEN · 2025PMID 39577691 ↗22The effect of vitamin D supplementation on mental and functional health outcomes in African Americans with type 2 diabetesJones KE, et al. · The Journal of steroid biochemistry and molecular biology · 2025PMID 39952368 ↗23Vitamin D Supplementation and Testosterone Levels in Breast Cancer SurvivorsMinopoli A, et al. · International journal of molecular sciences · 2025PMID 41155322 ↗24Effects of vitamin D3, omega-3s, and a simple strength training exercise program on bone health: the DO-HEALTH randomized controlled trialKistler-Fischbacher M, et al. · Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research · 2024PMID 38613445 ↗25Vitamin D deficiency and effect of treatment on seizure frequency and quality of life parameters in patients with drug-resistant epilepsy: A randomized clinical trialChassoux F, et al. · Epilepsia · 2024PMID 38980968 ↗26Vitamin D3 and deconvoluting a rashErnst MK, et al. · JCI insight · 2023PMID 36692020 ↗27Effects of Vitamin D(3) and Marine Omega-3 Fatty Acids Supplementation on Indicated and Selective Prevention of Depression in Older Adults: Results From the Clinical Center Sub-Cohort of the VITamin D and OmegA-3 TriaL (VITAL)Vyas CM, et al. · The Journal of clinical psychiatry · 2023PMID 37378490 ↗28Yeast Beta-Glucan Supplementation with Multivitamins Attenuates Cognitive Impairments in Individuals with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Randomized, Double-Blind, Placebo-Controlled TrialLacasa M, et al. · Nutrients · 2023PMID 37960157 ↗29Vitamin D and marine omega 3 fatty acid supplementation and incident autoimmune disease: VITAL randomized controlled trialHahn J, et al. · BMJ (Clinical research ed.) · 2022PMID 35082139 ↗30Supplemental Vitamin D and Incident Fractures in Midlife and Older AdultsLeBoff MS, et al. · The New England journal of medicine · 2022PMID 35939577 ↗31Effects of vitamin D supplementation on depression and some selected pro-inflammatory biomarkers: a double-blind randomized clinical trialKaviani M, et al. · BMC psychiatry · 2022PMID 36368945 ↗32Effect of Long-term Supplementation With Marine Omega-3 Fatty Acids vs Placebo on Risk of Depression or Clinically Relevant Depressive Symptoms and on Change in Mood Scores: A Randomized Clinical TrialOkereke OI, et al. · JAMA · 2021PMID 34932079 ↗33Effect of Long-term Vitamin D3 Supplementation vs Placebo on Risk of Depression or Clinically Relevant Depressive Symptoms and on Change in Mood Scores: A Randomized Clinical TrialOkereke OI, et al. · JAMA · 2020PMID 32749491 ↗34Effect of Vitamin D Supplementation, Omega-3 Fatty Acid Supplementation, or a Strength-Training Exercise Program on Clinical Outcomes in Older Adults: The DO-HEALTH Randomized Clinical TrialBischoff-Ferrari HA, et al. · JAMA · 2020PMID 33170239 ↗35Vitamin D(3) supplementation in multiple sclerosis: Symptoms and biomarkers of depressionRolf L, et al. · Journal of the neurological sciences · 2017PMID 28566173 ↗36Effect of maternal vitamin D(3) supplementation on maternal health, birth outcomes, and infant growth among HIV-infected Tanzanian pregnant women: study protocol for a randomized controlled trialSudfeld CR, et al. · Trials · 2017PMID 28870263 ↗37Vitamin D3 treatment of vitamin D-insufficient asthmatic patients does not alter immune cell functionReid B, et al. · The Journal of allergy and clinical immunology · 2016PMID 26874367 ↗38Effect of vitamin D3 on self-perceived fatigue: A double-blind randomized placebo-controlled trialNowak A, et al. · Medicine · 2016PMID 28033244 ↗39Vitamin D vs broad spectrum phototherapy in the treatment of seasonal affective disorderGloth FM 3rd, et al. · The journal of nutrition, health & aging · 1999PMID 10888476 ↗40Vitamin D3 enhances mood in healthy subjects during winterLansdowne AT, et al. · Psychopharmacology · 1998PMID 9539254 ↗
Published research results
Reported results grouped by condition. Values and units are preserved as recorded; missing information is not estimated.
How to read this table
- Benefit
- What the trial saw happen: whether the measured outcome moved in the helpful direction in that one study (the tag on each row: “Benefit seen”, “No clear benefit”, “Possible harm” or “Unclear”). It is a study result — not advice, and not a promise it will work for you.
- Evidence
- Study design describes how research was conducted. It is not a formal certainty assessment.
- Effect size
- The result recorded in this summary. “Not reported” means the value is missing from the summary; it does not establish that the publication omitted it.
Reported direction, numerical results and study design are separate. Certainty has not been formally graded in this table.
Bone Health (3 outcomes)
| What was measured | Reported findings | Result and units | Reported sample and duration | Study / source |
|---|---|---|---|---|
| hip fractures | Vitamin D3 did not significantly lower hip fracture risk vs placebo in 25,871 adults over a median of 5.3 years. (hazard ratio, 1.01; 95% CI, 0.70 to 1.47; P=0.96)No clear benefit | Not reported Recorded unit: Not reported | Sample (as reported): 25,871 Follow-up: median follow-up of 5.3 years | Randomised trial · 2022 Study detailsSupplemental Vitamin D and Incident Fractures in Midlife and Older Adults. Randomized Controlled Trial |
| nonvertebral fractures | Vitamin D3 did not significantly lower nonvertebral fracture risk vs placebo in 25,871 adults over a median of 5.3 years. (hazard ratio, 0.97; 95% CI, 0.87 to 1.07; P=0.50)No clear benefit | Not reported Recorded unit: Not reported | Sample (as reported): 25,871 Follow-up: median follow-up of 5.3 years | Randomised trial · 2022 Study detailsSupplemental Vitamin D and Incident Fractures in Midlife and Older Adults. Randomized Controlled Trial |
| total fractures | Vitamin D3 did not significantly lower total fracture risk vs placebo in 25,871 adults over a median of 5.3 years. (hazard ratio, 0.98; 95% confidence interval [CI], 0.89 to 1.08; P=0.70)No clear benefit | Not reported Recorded unit: Not reported | Sample (as reported): 25,871 Follow-up: median follow-up of 5.3 years | Randomised trial · 2022 Study detailsSupplemental Vitamin D and Incident Fractures in Midlife and Older Adults. Randomized Controlled Trial |
Depression (2 outcomes)
| What was measured | Reported findings | Result and units | Reported sample and duration | Study / source |
|---|---|---|---|---|
| Change in mood scores (PHQ-8) | Vitamin D3 showed no significant difference in mood score changes vs placebo in 18 353 adults over a median of 5.3 years. (mean difference for change in mood scores, 0.01 points [95% CI, -0.04 to 0.05 points])No clear benefit | Not reported Recorded unit: points | Sample (as reported): 18 353 Follow-up: median treatment duration was 5.3 years | Randomised trial · 2020 Study detailsEffect of Long-term Vitamin D3 Supplementation vs Placebo on Risk of Depression or Clinically Relevant Depressive Symptoms and on Change in Mood Scores: A Randomized Clinical Trial. Randomized Controlled Trial |
| Risk of depression or clinically relevant depressive symptoms | Vitamin D3 showed no significant difference in depression risk vs placebo in 18 353 adults over a median of 5.3 years. (hazard ratio, 0.97 [95% CI, 0.87 to 1.09]; P = .62)No clear benefit | Not reported Recorded unit: Not reported | Sample (as reported): 18 353 Follow-up: median treatment duration was 5.3 years | Randomised trial · 2020 Study detailsEffect of Long-term Vitamin D3 Supplementation vs Placebo on Risk of Depression or Clinically Relevant Depressive Symptoms and on Change in Mood Scores: A Randomized Clinical Trial. Randomized Controlled Trial |
Fatigue (2 outcomes)
| What was measured | Reported findings | Result and units | Reported sample and duration | Study / source |
|---|---|---|---|---|
| amelioration of fatigue | Fatigue amelioration occurred in 72% vs 50% placebo in 120 people over 4 weeks. (P=0.01; odds ratio [OR] 2.63, 95% CI for OR 1.23-5.62)Benefit seen | 72% Recorded unit: Not reported | Sample (as reported): 120 Follow-up: 4 weeks | Randomised trial · 2016 Study detailsEffect of vitamin D3 on self-perceived fatigue: A double-blind randomized placebo-controlled trial. Randomized Controlled Trial |
| intra-individual change in the fatigue assessment scale (FAS) | Fatigue scores improved by 3.3 points vs placebo in 120 people over 4 weeks. (95% confidence interval [CI] for change -14.1 to 4.1; P=0.01)Benefit seen | -3.3 Recorded unit: Not reported | Sample (as reported): 120 Follow-up: 4 weeks | Randomised trial · 2016 Study detailsEffect of vitamin D3 on self-perceived fatigue: A double-blind randomized placebo-controlled trial. Randomized Controlled Trial |
Important: This page reflects observational, aggregate-only community reporting and independent published research. It is not medical advice, and it does not claim any compound treats, cures, or is effective for any condition. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or treatment.
Outcomes & conditions
Outcomes & conditions →Why people look into Vitamin D3 — and what they report
Associated conditions and community-reported outcomes, wrapped together on one page. Aggregates appear only once enough reports arrive.
Important: This page reflects observational, aggregate-only community reporting and independent published research. It is not medical advice, and it does not claim any compound treats, cures, or is effective for any condition. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or treatment.
Availability
Where to get Vitamin D3 (UK)
How this compound is sold in the UK, and where our readers typically find it.
Retailer search links — we may earn commission on purchases at no cost to you. Commission never affects our evidence ratings.