Supplement

Vitamin D

Vitamin D is a vitamin your skin makes in sunlight, which the body uses like a hormone to absorb calcium and support bones and immune defenses. People mostly look at it to keep their levels adequate, since shortfalls are common worldwide, and the evidence is strong for that role; trials also found fewer falls and better bone density. The bone density findings rest on small studies, so the evidence there is only moderate.

Sources: PMID 28768407; PMID 19797342; PMID 39640483

Updated 30 September 2026
How we grade
100 studies cited

Best evidence: Grade A
Conditions studied: 73
Outcomes: 308
Graded outcomes: 3112215

Evidence by condition

Strong
Moderate
Limited
Very limited

73 conditions

Fall Prevention

Fall Prevention: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People
	Fall Risk Moderate Improvement	Improves (the measure goes down)	Moderate effect	3 studies	2,426 people
Studies that measured fall risk Fall prevention with supplemental and active forms of vitamin D: a meta-analysis of randomised controlled trialsBMJ · PMID 19797342 A higher dose of vitamin d reduces the risk of falls in nursing home residents: a randomized, multiple-dose studyJ Am Geriatr Soc · PMID 17302660 The Relationship of Falls With Achieved 25-Hydroxyvitamin D Levels From Vitamin D Supplementation: The STURDY Trial.J Endocr Soc · PMID 35592513
	Functionality in Elderly or Injured	Improves (the measure goes up)		1 study	688 people
Studies that measured functionality in elderly or injured Effects of Vitamin D on Physical Function: Results From the STURDY Trial.J Gerontol A Biol Sci Med Sci · PMID 34928336

Preeclampsia

Preeclampsia: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People
	Pre-Eclampsia Risk Moderate Improvement	Improves (the measure goes down)	Moderate effect	1 study	5,035 people
Studies that measured pre-eclampsia risk Efficacy of vitamin D supplementation on the incidence of preeclampsia: a systematic review and meta-analysis.BMC Pregnancy Childbirth · PMID 39716171
	Preterm Birth Risk	Changes; see studies			6,055 people

Pregnancy and Delivery Health

Pre-Eclampsia Risk: improves
Preterm Birth Risk: changes; see studies

Pregnancy and Delivery Health: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People
	Pre-Eclampsia Risk Moderate Improvement	Improves (the measure goes down)	Moderate effect	1 study	5,035 people
Studies that measured pre-eclampsia risk Efficacy of vitamin D supplementation on the incidence of preeclampsia: a systematic review and meta-analysis.BMC Pregnancy Childbirth · PMID 39716171
	Preterm Birth Risk	Changes; see studies			6,055 people

Vitamin D Deficiency

Depression Symptoms: improves
Fibromyalgia Symptoms: improves

Vitamin D Deficiency: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People
	Depression Symptoms Small Improvement	Improves (the measure goes down)	Small effect	5 studies	679 people
Studies that measured depression symptoms Efficacy of vitamin D supplementation on depressive symptoms in older patients: a meta-analysis of randomized controlled trials.Front Med · PMID 39450108 Evaluating the effects of vitamin D and vitamin E supplement on premenstrual syndrome: A randomized, double-blind, controlled trialIran J Nurs Midwifery Res · PMID 27095989 Effects of cholecalciferol supplementation on depressive symptoms, C-peptide, serotonin, and neurotrophin-3 in type 2 diabetes mellitus: A double-blind, randomized, placebo-controlled trial.Narra J · PMID 39816051 The effect of vitamin D supplementation on depression: a systematic review and dose-response meta-analysis of randomized controlled trials.Psychol Med · PMID 39552387 Vitamin D protects against depression: Evidence from an umbrella meta-analysis on interventional and observational meta-analyses.Pharmacol Res · PMID 36509315
	Fibromyalgia Symptoms	Improves (the measure goes down)		4 studies	137 people
Studies that measured fibromyalgia symptoms Effects of vitamin D on patients with fibromyalgia syndrome: a randomized placebo-controlled trialPain · PMID 24438771 Vitamin D Supplementation Seems to Improve Fibromyalgia Symptoms: Preliminary ResultsIsr Med Assoc J · PMID 29911760 Effects of Vitamin D Therapy on Quality of Life in Patients with FibromyalgiaEurasian J Med · PMID 28638253 Correlation of symptoms with vitamin D deficiency and symptom response to cholecalciferol treatment: a randomized controlled trialEndocr Pract · PMID 19364687

Common Cold

Influenza Risk: improves
Upper Respiratory Tract Infection Risk: changes; see studies
Upper Respiratory Tract Infection Symptoms: improves

Common Cold: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People
	Influenza Risk Small Improvement	Improves (the measure goes down)	Small effect	2 studies	2,003 people
Studies that measured influenza risk Vitamin D supplementation did not prevent influenza-like illness as diagnosed retrospectively by questionnaires in subjects participating in randomized clinical trialsScand J Infect Dis · PMID 22026455 Effects of vitamin D supplements on influenza A illness during the 2009 H1N1 pandemic: a randomized controlled trialFood Funct · PMID 25088394
	Upper Respiratory Tract Infection Risk	Changes; see studies		13 studies	5,265 people
Studies that measured upper respiratory tract infection risk The effects of prenatal vitamin D supplementation on respiratory and allergy-related outcomes in children: A systematic review and meta-analysis of randomized controlled trials.World Allergy Organ J · PMID 40535465 High-Dose Monthly Vitamin D for Prevention of Acute Respiratory Infection in Older Long-Term Care Residents: A Randomized Clinical TrialJ Am Geriatr Soc · PMID 27861708 Randomized trial of vitamin D supplementation and risk of acute respiratory infection in MongoliaPediatrics · PMID 22908115 Reduced primary care respiratory infection visits following pregnancy and infancy vitamin D supplementation: a randomised controlled trialActa Paediatr · PMID 25283480 Vitamin D supplementation to prevent acute respiratory infections: individual participant data meta-analysisHealth Technol Assess · PMID 30675873 Effect of High-Dose vs Standard-Dose Wintertime Vitamin D Supplementation on Viral Upper Respiratory Tract Infections in Young Healthy ChildrenJAMA · PMID 28719693 Vitamin D supplementation to prevent infections: a sub-study of a randomised placebo-controlled trial in older people (RECORD trial, ISRCTN 51647438)Age Ageing · PMID 17702768 Vitamin D3 supplementation and upper respiratory tract infections in a randomized, controlled trialClin Infect Dis · PMID 24014734 Effect of monthly high-dose vitamin D supplementation on acute respiratory infections in older adults: A randomized controlled trialClin Infect Dis · PMID 31420647 Vitamin D3 supplementation in patients with frequent respiratory tract infections: a randomised and double-blind intervention studyBMJ Open · PMID 23242238 and 3 more in the citations list
	Upper Respiratory Tract Infection Symptoms	Improves (the measure goes down)		13 studies	2,352 people
Studies that measured upper respiratory tract infection symptoms Double-blind randomised placebo-controlled trial of bolus-dose vitamin D3 supplementation in adults with asthma (ViDiAs)Thorax · PMID 25724847 Vitamin D Supplementation and the Risk of Colds in Patients with AsthmaAm J Respir Crit Care Med · PMID 26540136 Vitamin D supplementation and upper respiratory tract infections in adolescent swimmers: a randomized controlled trialPediatr Exerc Sci · PMID 25050610 Effect of vitamin D3 supplementation on upper respiratory tract infections in healthy adults: the VIDARIS randomized controlled trialJAMA · PMID 23032549 Vitamin D3 and gargling for the prevention of upper respiratory tract infections: a randomized controlled trialBMC Infect Dis · PMID 24885201 Intake of 25-Hydroxyvitamin D3 Reduces Duration and Severity of Upper Respiratory Tract Infection: A Randomized, Double-Blind, Placebo-Controlled, Parallel Group Comparison StudyJ Nutr Health Aging · PMID 29582888 Vitamin D₃ Supplementation Reduces the Symptoms of Upper Respiratory Tract Infection during Winter Training in Vitamin D-Insufficient Taekwondo Athletes: A Randomized Controlled TrialInt J Environ Res Public Health · PMID 30223447 A randomized controlled trial of vitamin D3 supplementation for the prevention of symptomatic upper respiratory tract infectionsEpidemiol Infect · PMID 19296870 Vitamin D supplementation for the prevention of acute respiratory tract infection: a randomized, double-blinded trial among young Finnish menJ Infect Dis · PMID 20632889 Double-blind randomised controlled trial of vitamin D3 supplementation for the prevention of acute respiratory infection in older adults and their carers (ViDiFlu)Thorax · PMID 26063508 and 3 more in the citations list
	Lower Respiratory Tract Infection Risk	Changes; see studies			240 people

Type 2 Diabetes

Blood glucose: improves
Depression Symptoms: improves
Glycemic Control: improves

Type 2 Diabetes: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People
	Blood glucose Small Improvement	Improves (the measure goes down)	Small effect	2 studies	2,982 people
Studies that measured blood glucose Effect of vitamin D3 supplementation on vascular and metabolic health of vitamin D-deficient overweight and obese children: a randomized clinical trial.Am J Clin Nutr · PMID 31950134 The impact of vitamin D supplementation on glycemic control and lipid metabolism in polycystic ovary syndrome: a systematic review of randomized controlled trials.BMC Endocr Disord · PMID 40259331
	Depression Symptoms	Improves (the measure goes down)		5 studies	70 people
Studies that measured depression symptoms Efficacy of vitamin D supplementation on depressive symptoms in older patients: a meta-analysis of randomized controlled trials.Front Med · PMID 39450108 Evaluating the effects of vitamin D and vitamin E supplement on premenstrual syndrome: A randomized, double-blind, controlled trialIran J Nurs Midwifery Res · PMID 27095989 Effects of cholecalciferol supplementation on depressive symptoms, C-peptide, serotonin, and neurotrophin-3 in type 2 diabetes mellitus: A double-blind, randomized, placebo-controlled trial.Narra J · PMID 39816051 The effect of vitamin D supplementation on depression: a systematic review and dose-response meta-analysis of randomized controlled trials.Psychol Med · PMID 39552387 Vitamin D protects against depression: Evidence from an umbrella meta-analysis on interventional and observational meta-analyses.Pharmacol Res · PMID 36509315
	Glycemic Control	Improves (the measure goes up)		4 studies	99 people
Studies that measured glycemic control Impact of vitamin D supplementation during a resistance training intervention on body composition, muscle function, and glucose tolerance in overweight and obese adultsClin Nutr · PMID 23034474 A randomized, placebo-controlled trial of vitamin D supplementation to improve glycaemia in overweight and obese African AmericansDiabetes Obes Metab · PMID 22486948 The effect of vitamin D3 on insulin secretion and peripheral insulin sensitivity in type 2 diabetic patientsInt J Clin Pract · PMID 12800453 Vitamin D3 supplementation improves insulin sensitivity in subjects with impaired fasting glucoseTransl Res · PMID 22005267
	Insulin	Changes; see studies		3 studies	2,982 people
Studies that measured insulin Effects of vitamin D and calcium supplementation on pancreatic β cell function, insulin sensitivity, and glycemia in adults at high risk of diabetes: the Calcium and Vitamin D for Diabetes Mellitus (CaDDM) randomized controlled trialAm J Clin Nutr · PMID 21715514 Efficacy of vitamin D supplementation on glycaemic control in type 2 diabetes: An updated systematic review and meta-analysis of randomized controlled trials.Diabetes Obes Metab · PMID 39355942 Vitamin D Supplementation Affects the Beck Depression Inventory, Insulin Resistance, and Biomarkers of Oxidative Stress in Patients with Major Depressive Disorder: A Randomized, Controlled Clinical TrialJ Nutr · PMID 26609167
	Low-density lipoprotein (LDL)	Improves (the measure goes down)		3 studies	1 person
Studies that measured low-density lipoprotein (ldl) Vitamin D3 supplementation does not modify cardiovascular risk profile of adults with inadequate vitamin D statusEur J Nutr · 2015 · PMID 26621634 The effect of vitamin D supplementation on clinical symptoms and metabolic profiles in patients with endometriosisGynecol Endocrinol · PMID 33508990 Vitamin D supplementation enhances the beneficial effects of weight loss on cardiovascular disease risk markersAm J Clin Nutr · PMID 19321573
	Weight	Improves (the measure goes down)		2 studies	1 person
	HbA1c	Improves (the measure goes down)		1 study	2,982 people
	Insulin Resistance	Improves (the measure goes down)		1 study	2,982 people
	Type 2 Diabetes Incidence	Changes; see studies		1 study	27,425 people
	High-density lipoprotein (HDL)	Improves (the measure goes up)			1 person
	Total cholesterol	Improves (the measure goes down)			1 person
	Triglycerides	Improves (the measure goes down)			1 person
	Waist circumference	Improves (the measure goes down)			1 person

Premenstrual Syndrome (PMS)

Anxiety Symptoms: improves
Depression Symptoms: improves
Cramps: improves

Premenstrual Syndrome (PMS): outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People
	Anxiety Symptoms Small Improvement	Improves (the measure goes down)	Small effect	2 studies	346 people
Studies that measured anxiety symptoms The Effect of Vitamin D Supplement Consumption on Premenstrual Syndrome in Vitamin D-Deficient Young Girls: A Randomized, Double-Blind, Placebo-Controlled Clinical TrialComplement Med Res · PMID 31104056 Vitamin D Supplementation for Premenstrual Syndrome-Related Mood Disorders in Adolescents with Severe Hypovitaminosis DJ Pediatr Adolesc Gynecol · PMID 26724745
	Depression Symptoms	Improves (the measure goes down)		5 studies	58 people
Studies that measured depression symptoms Efficacy of vitamin D supplementation on depressive symptoms in older patients: a meta-analysis of randomized controlled trials.Front Med · PMID 39450108 Evaluating the effects of vitamin D and vitamin E supplement on premenstrual syndrome: A randomized, double-blind, controlled trialIran J Nurs Midwifery Res · PMID 27095989 Effects of cholecalciferol supplementation on depressive symptoms, C-peptide, serotonin, and neurotrophin-3 in type 2 diabetes mellitus: A double-blind, randomized, placebo-controlled trial.Narra J · PMID 39816051 The effect of vitamin D supplementation on depression: a systematic review and dose-response meta-analysis of randomized controlled trials.Psychol Med · PMID 39552387 Vitamin D protects against depression: Evidence from an umbrella meta-analysis on interventional and observational meta-analyses.Pharmacol Res · PMID 36509315
	Cramps	Improves (the measure goes down)		1 study	897 people
Studies that measured cramps High dose vitamin D supplementation can improve menstrual problems, dysmenorrhea, and premenstrual syndrome in adolescentsGynecol Endocrinol · PMID 29447494
	Total Antioxidant Capacity (TAC)	Improves (the measure goes up)		1 study	44 people
Studies that measured total antioxidant capacity (tac) Vitamin D Supplementation for Premenstrual Syndrome-Related inflammation and antioxidant markers in students with vitamin D deficient: a randomized clinical trialSci Rep · PMID 31624297
	Fatigue Symptoms	Improves (the measure goes down)			130 people
	Interleukin 10	Improves (the measure goes up)			44 people
	Interleukin 12	Improves (the measure goes up)			44 people
	PMS Symptoms	Improves (the measure goes down)			1,287 people

Osteoporosis

Bone Mineral Density: improves
Fracture Risk: changes; see studies
Bone-specific Alkaline Phosphatase: improves

Osteoporosis: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People
	Bone Mineral Density Small Improvement	Improves (the measure goes up)	Small effect	2 studies	5,522 people
Studies that measured bone mineral density Efficacy of combination therapy of vitamin D and bisphosphonates in the treatment of postmenopausal osteoporosis: a systematic review and meta-analysis.Front Pharmacol · PMID 39640483 Changes in bone density and microarchitecture following treatment of Graves' disease and the effects of vitamin D supplementation. A randomized clinical trial.Osteoporos Int · PMID 39264438
	Fracture Risk	Changes; see studies		1 study	42,279 people
Studies that measured fracture risk Prevention of nonvertebral fractures with oral vitamin D and dose dependency: a meta-analysis of randomized controlled trialsArch Intern Med · PMID 19307517
	Bone-specific Alkaline Phosphatase	Improves (the measure goes up)			8,058 people

Nonalcoholic Fatty Liver Disease (NAFLD)

Blood glucose: improves
Insulin: changes; see studies
Low-density lipoprotein (LDL): improves

Nonalcoholic Fatty Liver Disease (NAFLD): outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People
	Blood glucose Small Improvement	Improves (the measure goes down)	Small effect	2 studies	1 person
Studies that measured blood glucose Effect of vitamin D3 supplementation on vascular and metabolic health of vitamin D-deficient overweight and obese children: a randomized clinical trial.Am J Clin Nutr · PMID 31950134 The impact of vitamin D supplementation on glycemic control and lipid metabolism in polycystic ovary syndrome: a systematic review of randomized controlled trials.BMC Endocr Disord · PMID 40259331
	Insulin	Changes; see studies		3 studies	1 person
Studies that measured insulin Effects of vitamin D and calcium supplementation on pancreatic β cell function, insulin sensitivity, and glycemia in adults at high risk of diabetes: the Calcium and Vitamin D for Diabetes Mellitus (CaDDM) randomized controlled trialAm J Clin Nutr · PMID 21715514 Efficacy of vitamin D supplementation on glycaemic control in type 2 diabetes: An updated systematic review and meta-analysis of randomized controlled trials.Diabetes Obes Metab · PMID 39355942 Vitamin D Supplementation Affects the Beck Depression Inventory, Insulin Resistance, and Biomarkers of Oxidative Stress in Patients with Major Depressive Disorder: A Randomized, Controlled Clinical TrialJ Nutr · PMID 26609167
	Low-density lipoprotein (LDL)	Improves (the measure goes down)		3 studies	1 person
Studies that measured low-density lipoprotein (ldl) Vitamin D3 supplementation does not modify cardiovascular risk profile of adults with inadequate vitamin D statusEur J Nutr · 2015 · PMID 26621634 The effect of vitamin D supplementation on clinical symptoms and metabolic profiles in patients with endometriosisGynecol Endocrinol · PMID 33508990 Vitamin D supplementation enhances the beneficial effects of weight loss on cardiovascular disease risk markersAm J Clin Nutr · PMID 19321573
	Weight	Improves (the measure goes down)		2 studies	1 person
Studies that measured weight Can Vitamin D supplementation enhance the effectiveness of exercise-induced weight loss in overweight or obese adults? Evidence from integrated transcriptomic and meta-analysisFront Nutr · PMID 41098796 Effect of vitamin D supplementation on body composition, lipid profile, and glycemic indices in patients with obesity-associated metabolic syndrome: a systematic review and meta-analysis.Diabetol Metab Syndr · PMID 40682197
	HbA1c	Improves (the measure goes down)		1 study	1 person
Studies that measured hba1c Association of A1C levels with vitamin D status in U.S. adults: data from the National Health and Nutrition Examination SurveyDiabetes Care · 2010 · PMID 20215453
	Insulin Resistance	Improves (the measure goes down)		1 study	1 person
	High-density lipoprotein (HDL)	Improves (the measure goes up)			1 person
	Total cholesterol	Improves (the measure goes down)			1 person
	Triglycerides	Improves (the measure goes down)			1 person
	Waist circumference	Improves (the measure goes down)			1 person

Metabolic Syndrome

Blood glucose: improves
Insulin: changes; see studies
Low-density lipoprotein (LDL): improves

Metabolic Syndrome: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People
	Blood glucose Small Improvement	Improves (the measure goes down)	Small effect	2 studies	1 person
Studies that measured blood glucose Effect of vitamin D3 supplementation on vascular and metabolic health of vitamin D-deficient overweight and obese children: a randomized clinical trial.Am J Clin Nutr · PMID 31950134 The impact of vitamin D supplementation on glycemic control and lipid metabolism in polycystic ovary syndrome: a systematic review of randomized controlled trials.BMC Endocr Disord · PMID 40259331
	Insulin	Changes; see studies		3 studies	1 person
Studies that measured insulin Effects of vitamin D and calcium supplementation on pancreatic β cell function, insulin sensitivity, and glycemia in adults at high risk of diabetes: the Calcium and Vitamin D for Diabetes Mellitus (CaDDM) randomized controlled trialAm J Clin Nutr · PMID 21715514 Efficacy of vitamin D supplementation on glycaemic control in type 2 diabetes: An updated systematic review and meta-analysis of randomized controlled trials.Diabetes Obes Metab · PMID 39355942 Vitamin D Supplementation Affects the Beck Depression Inventory, Insulin Resistance, and Biomarkers of Oxidative Stress in Patients with Major Depressive Disorder: A Randomized, Controlled Clinical TrialJ Nutr · PMID 26609167
	Low-density lipoprotein (LDL)	Improves (the measure goes down)		3 studies	1 person
Studies that measured low-density lipoprotein (ldl) Vitamin D3 supplementation does not modify cardiovascular risk profile of adults with inadequate vitamin D statusEur J Nutr · 2015 · PMID 26621634 The effect of vitamin D supplementation on clinical symptoms and metabolic profiles in patients with endometriosisGynecol Endocrinol · PMID 33508990 Vitamin D supplementation enhances the beneficial effects of weight loss on cardiovascular disease risk markersAm J Clin Nutr · PMID 19321573
	Weight	Improves (the measure goes down)		2 studies	1 person
Studies that measured weight Can Vitamin D supplementation enhance the effectiveness of exercise-induced weight loss in overweight or obese adults? Evidence from integrated transcriptomic and meta-analysisFront Nutr · PMID 41098796 Effect of vitamin D supplementation on body composition, lipid profile, and glycemic indices in patients with obesity-associated metabolic syndrome: a systematic review and meta-analysis.Diabetol Metab Syndr · PMID 40682197
	HbA1c	Improves (the measure goes down)		1 study	1 person
Studies that measured hba1c Association of A1C levels with vitamin D status in U.S. adults: data from the National Health and Nutrition Examination SurveyDiabetes Care · 2010 · PMID 20215453
	Insulin Resistance	Improves (the measure goes down)		1 study	1 person
	High-density lipoprotein (HDL)	Improves (the measure goes up)			1 person
	Total cholesterol	Improves (the measure goes down)			1 person
	Triglycerides	Improves (the measure goes down)			1 person
	Waist circumference	Improves (the measure goes down)			1 person

Mood Improvement

Anxiety Symptoms: improves
Depression Symptoms: improves

Mood Improvement: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People
	Anxiety Symptoms Small Improvement	Improves (the measure goes down)	Small effect	2 studies	641 people
Studies that measured anxiety symptoms The Effect of Vitamin D Supplement Consumption on Premenstrual Syndrome in Vitamin D-Deficient Young Girls: A Randomized, Double-Blind, Placebo-Controlled Clinical TrialComplement Med Res · PMID 31104056 Vitamin D Supplementation for Premenstrual Syndrome-Related Mood Disorders in Adolescents with Severe Hypovitaminosis DJ Pediatr Adolesc Gynecol · PMID 26724745
	Depression Symptoms	Improves (the measure goes down)		5 studies	24,189 people
Studies that measured depression symptoms Efficacy of vitamin D supplementation on depressive symptoms in older patients: a meta-analysis of randomized controlled trials.Front Med · PMID 39450108 Evaluating the effects of vitamin D and vitamin E supplement on premenstrual syndrome: A randomized, double-blind, controlled trialIran J Nurs Midwifery Res · PMID 27095989 Effects of cholecalciferol supplementation on depressive symptoms, C-peptide, serotonin, and neurotrophin-3 in type 2 diabetes mellitus: A double-blind, randomized, placebo-controlled trial.Narra J · PMID 39816051 The effect of vitamin D supplementation on depression: a systematic review and dose-response meta-analysis of randomized controlled trials.Psychol Med · PMID 39552387 Vitamin D protects against depression: Evidence from an umbrella meta-analysis on interventional and observational meta-analyses.Pharmacol Res · PMID 36509315

Depression

Combined Anxiety & Depression: improves
Depression Symptoms: improves

Depression: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People
	Combined Anxiety & Depression Small Improvement	Improves (the measure goes down)	Small effect	1 study	7,534 people
Studies that measured combined anxiety & depression The Effect of Vitamin D Supplement on Negative Emotions: A Systematic Review and Meta-AnalysisDepress Anxiety · PMID 32365423
	Depression Symptoms	Improves (the measure goes down)		5 studies	24,510 people
Studies that measured depression symptoms Efficacy of vitamin D supplementation on depressive symptoms in older patients: a meta-analysis of randomized controlled trials.Front Med · PMID 39450108 Evaluating the effects of vitamin D and vitamin E supplement on premenstrual syndrome: A randomized, double-blind, controlled trialIran J Nurs Midwifery Res · PMID 27095989 Effects of cholecalciferol supplementation on depressive symptoms, C-peptide, serotonin, and neurotrophin-3 in type 2 diabetes mellitus: A double-blind, randomized, placebo-controlled trial.Narra J · PMID 39816051 The effect of vitamin D supplementation on depression: a systematic review and dose-response meta-analysis of randomized controlled trials.Psychol Med · PMID 39552387 Vitamin D protects against depression: Evidence from an umbrella meta-analysis on interventional and observational meta-analyses.Pharmacol Res · PMID 36509315

Migraine Headache

Migraine Frequency: improves
Migraine Severity: improves

Migraine Headache: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Migraine Frequency Small Decrease	Improves (the measure goes down)	Small effect		122 people
	Migraine Severity	Improves (the measure goes down)			122 people

Parkinson's Disease

6-Minute Walking Test Performance: improves
Parkinson's Disease Symptoms: improves
Walking Ability: improves

Parkinson's Disease: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
6-Minute Walking Test Performance Small Improvement	Improves (the measure goes up)	Small effect		191 people
Parkinson's Disease Symptoms	Improves (the measure goes down)		1 study	518 people
Walking Ability	Improves (the measure goes up)			191 people

Major Depressive Disorder (MDD)

Depression Symptoms: improves
Glycemic Control: improves
Insulin: changes; see studies

Major Depressive Disorder (MDD): outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Depression Symptoms Small Improvement	Improves (the measure goes down)	Small effect	5 studies	40 people
Glycemic Control	Improves (the measure goes up)		4 studies	40 people
Insulin	Changes; see studies		3 studies	40 people

Acute Respiratory Infection (ARI)

Asthma Symptoms: improves
Upper Respiratory Tract Infection Risk: changes; see studies
COPD Symptoms: improves

Acute Respiratory Infection (ARI): outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Asthma Symptoms Small Improvement	Improves (the measure goes down)	Small effect	2 studies	11,321 people
Upper Respiratory Tract Infection Risk	Changes; see studies		13 studies	3,958 people
COPD Symptoms	Improves (the measure goes down)			11,321 people
Lower Respiratory Tract Infection Risk	Changes; see studies			10,993 people

Endometriosis

Blood glucose: improves
Glycemic Control: improves
Insulin: changes; see studies

Endometriosis: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Blood glucose Small Improvement	Improves (the measure goes down)	Small effect	2 studies	60 people
Glycemic Control	Improves (the measure goes up)		4 studies	60 people
Insulin	Changes; see studies		3 studies	60 people
Low-density lipoprotein (LDL)	Improves (the measure goes down)		3 studies	60 people
Endometriosis-associated pelvic pain	Improves (the measure goes down)		1 study	108 people
Insulin Resistance	Improves (the measure goes down)		1 study	60 people
Pelvic Pain	Improves (the measure goes down)		1 study	510 people
Total Antioxidant Capacity (TAC)	Improves (the measure goes up)		1 study	60 people
C-Reactive Protein (CRP)	Improves (the measure goes down)			60 people
Dyschezia	Improves (the measure goes up)			60 people
Dysmenorrhea Symptoms	Improves (the measure goes down)			99 people
Dyspareunia	Improves (the measure goes up)			60 people
Glutathione (GSH)	Improves (the measure goes up)			60 people
High-density lipoprotein (HDL)	Improves (the measure goes up)			60 people
Oxidative Stress Biomarkers	Improves (the measure goes down)			60 people
Total cholesterol	Improves (the measure goes down)			60 people
Total-/HDL-cholesterol ratio	Changes; see studies			60 people
Triglycerides	Improves (the measure goes down)			60 people
vLDL-C	Improves (the measure goes down)			60 people

Flu

Asthma Symptoms: improves
Upper Respiratory Tract Infection Symptoms: improves
Influenza Risk: changes; see studies

Flu: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Asthma Symptoms Small Improvement	Improves (the measure goes down)	Small effect	2 studies	334 people
Upper Respiratory Tract Infection Symptoms	Improves (the measure goes down)		13 studies	332 people
Influenza Risk	Changes; see studies		2 studies	1,482 people
Fever	Improves (the measure goes up)		1 study	334 people
Pneumonia Symptoms	Improves (the measure goes down)		1 study	334 people

General Cardiovascular Health

Blood Pressure: improves
Low-density lipoprotein (LDL): improves
Risk Of Cardiovascular Disease: improves

General Cardiovascular Health: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Blood Pressure Small Improvement	Improves (the measure goes down)	Small effect	2 studies	12,749 people
Low-density lipoprotein (LDL)	Improves (the measure goes down)		3 studies	105 people
Risk Of Cardiovascular Disease	Improves (the measure goes down)		3 studies	57,201 people
Inflammation	Improves (the measure goes down)		2 studies	34 people
Cardiovascular Disease Mortality	Improves (the measure goes down)			28,366 people
Hematocrit	Improves (the measure goes up)			105 people
Hemoglobin	Improves (the measure goes up)			105 people
High-density lipoprotein (HDL)	Improves (the measure goes up)			105 people
Red Blood Cell Count	Improves (the measure goes up)			105 people
Vascular Function	Improves (the measure goes up)			34 people

Polycystic Ovary Syndrome (PCOS)

Blood glucose: improves
Insulin: changes; see studies
Low-density lipoprotein (LDL): improves

Polycystic Ovary Syndrome (PCOS): outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Blood glucose Small Improvement	Improves (the measure goes down)	Small effect	2 studies	691 people
Insulin	Changes; see studies		3 studies	691 people
Low-density lipoprotein (LDL)	Improves (the measure goes down)		3 studies	691 people
High-density lipoprotein (HDL)	Improves (the measure goes up)			691 people
Total cholesterol	Improves (the measure goes down)			691 people
Triglycerides	Improves (the measure goes down)			691 people
vLDL-C	Improves (the measure goes down)			691 people

Graves’ Disease

Bone Mineral Density: improves

Graves’ Disease: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Bone Mineral Density Small Improvement	Improves (the measure goes up)	Small effect	2 studies	86 people

Bone Health

Bone turnover markers: improves
Calcium Absorption: improves
Fracture Risk: changes; see studies

Bone Health: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Bone turnover markers Small Improvement	Improves (the measure goes down)	Small effect	1 study	91 people
Calcium Absorption	Improves (the measure goes up)		1 study	64 people
Fracture Risk	Changes; see studies		1 study	42,279 people
Parathyroid Hormone	Improves (the measure goes up)		1 study	64 people

Breast Cancer

Aromatase-Inhibitor Related Joint Pain: improves
Breast Cancer Risk: changes; see studies

Breast Cancer: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Aromatase-Inhibitor Related Joint Pain Small Improvement	Improves (the measure goes down)	Small effect	1 study	60 people
	Breast Cancer Risk	Changes; see studies		2 studies	3,861 people

Primary Dysmenorrhea (Menstrual Cramps)

Cramps: improves
Pelvic Pain: improves
PMS Symptoms: improves

Primary Dysmenorrhea (Menstrual Cramps): outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Cramps Small Improvement	Improves (the measure goes down)	Small effect	1 study	897 people
Pelvic Pain	Improves (the measure goes down)		1 study	510 people
PMS Symptoms	Improves (the measure goes down)			897 people

Muscle Size Strength

Interleukin 5: improves
Power Output: improves

Muscle Size Strength: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Interleukin 5 Small Increase	Improves (the measure goes up)	Small effect	1 study	30 people
	Power Output	Improves (the measure goes up)		1 study	20 people

General Athletic Performance

Interleukin 5: improves
Power Output: improves

General Athletic Performance: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Interleukin 5 Small Increase	Improves (the measure goes up)	Small effect	1 study	30 people
	Power Output	Improves (the measure goes up)		1 study	20 people

Infant Health

Liver Enzymes: improves
Upper Respiratory Tract Infection Risk: changes; see studies
Parathyroid Hormone: improves

Infant Health: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Liver Enzymes Moderate Improvement	Improves (the measure goes down)	Moderate effect	1 study	230 people
Upper Respiratory Tract Infection Risk	Changes; see studies		13 studies	230 people
Parathyroid Hormone	Improves (the measure goes up)		1 study	230 people

Muscle Size & Strength

Interleukin 5: improves
Power Output: improves

Muscle Size & Strength: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Interleukin 5 Small Increase	Improves (the measure goes up)	Small effect	1 study	30 people
	Power Output	Improves (the measure goes up)		1 study	20 people

Upper Respiratory Tract Infection

Bacterial Infection: improves
Body Fat: improves
Upper Respiratory Tract Infection Risk: changes; see studies

Upper Respiratory Tract Infection: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Bacterial Infection Moderate Improvement	Improves (the measure goes up)	Moderate effect		140 people
Body Fat Small Decrease	Improves (the measure goes down)	Small effect		25 people
Upper Respiratory Tract Infection Risk	Changes; see studies		13 studies	18,909 people
Upper Respiratory Tract Infection Symptoms	Improves (the measure goes down)		13 studies	2,971 people
Influenza Risk	Changes; see studies		2 studies	2,003 people
Weight	Improves (the measure goes down)		2 studies	25 people
Fever	Improves (the measure goes up)		1 study	164 people
Muscle Mass	Improves (the measure goes up)		1 study	25 people
Cough	Changes; see studies			164 people
Lower Respiratory Tract Infection Risk	Changes; see studies			5,110 people

Immune Health

Body Fat: improves
Upper Respiratory Tract Infection Risk: changes; see studies
Upper Respiratory Tract Infection Symptoms: improves

Immune Health: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Body Fat Small Decrease	Improves (the measure goes down)	Small effect		165 people
Upper Respiratory Tract Infection Risk	Changes; see studies		13 studies	152 people
Upper Respiratory Tract Infection Symptoms	Improves (the measure goes down)		13 studies	68 people
Low-density lipoprotein (LDL)	Improves (the measure goes down)		3 studies	165 people
Interleukin 5	Improves (the measure goes up)		1 study	30 people
Parathyroid Hormone	Improves (the measure goes up)		1 study	165 people
Tuberculosis Symptoms	Improves (the measure goes down)		1 study	120 people
Metabolic Rate	Improves (the measure goes up)			165 people
TNF-Alpha	Improves (the measure goes down)			165 people
Triglycerides	Improves (the measure goes down)			165 people

Coronary Artery Disease (CAD)

Body Fat: improves
Low-density lipoprotein (LDL): improves
Risk Of Cardiovascular Disease: improves

Coronary Artery Disease (CAD): outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Body Fat Small Decrease	Improves (the measure goes down)	Small effect		165 people
Low-density lipoprotein (LDL)	Improves (the measure goes down)		3 studies	165 people
Risk Of Cardiovascular Disease	Improves (the measure goes down)		3 studies	2,988 people
Weight	Improves (the measure goes down)		2 studies	165 people
Parathyroid Hormone	Improves (the measure goes up)		1 study	165 people
Metabolic Rate	Improves (the measure goes up)			165 people
TNF-Alpha	Improves (the measure goes down)			165 people
Triglycerides	Improves (the measure goes down)			165 people

Tuberculosis (TB)

Height: improves
Tuberculosis risk: changes; see studies
Tuberculosis Symptoms: improves

Tuberculosis (TB): outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Height Small Increase	Improves (the measure goes up)	Small effect		120 people
Tuberculosis risk	Changes; see studies		1 study
Tuberculosis Symptoms	Improves (the measure goes down)		1 study	120 people

High Cholesterol

Body Fat: improves
Low-density lipoprotein (LDL): improves
Weight: improves

High Cholesterol: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Body Fat Small Decrease	Improves (the measure goes down)	Small effect		165 people
Low-density lipoprotein (LDL)	Improves (the measure goes down)		3 studies	165 people
Weight	Improves (the measure goes down)		2 studies	165 people
Parathyroid Hormone	Improves (the measure goes up)		1 study	165 people
Metabolic Rate	Improves (the measure goes up)			165 people
TNF-Alpha	Improves (the measure goes down)			165 people
Triglycerides	Improves (the measure goes down)			165 people

Sleep Health

Fatigue Symptoms: improves
Sleep Duration: improves
Sleep Latency: improves

Sleep Health: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Fatigue Symptoms Small Improvement	Improves (the measure goes down)	Small effect		93 people
Sleep Duration	Improves (the measure goes up)		1 study	93 people
Sleep Latency	Improves (the measure goes down)			93 people
Sleep Quality	Improves (the measure goes up)			93 people

Weight Loss & Maintenance

Body Fat: improves
Low-density lipoprotein (LDL): improves
Weight: improves

Weight Loss & Maintenance: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Body Fat Small Decrease	Improves (the measure goes down)	Small effect		165 people
Low-density lipoprotein (LDL)	Improves (the measure goes down)		3 studies	165 people
Weight	Improves (the measure goes down)		2 studies	165 people
Parathyroid Hormone	Improves (the measure goes up)		1 study	165 people
Metabolic Rate	Improves (the measure goes up)			165 people
TNF-Alpha	Improves (the measure goes down)			165 people
Triglycerides	Improves (the measure goes down)			165 people

Menopause

Inflammation
Vascular Function: improves

Menopause: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Inflammation No effect		NoneNo effect	2 studies	34 people
	Vascular Function	Improves (the measure goes up)			34 people

COVID-19

All-Cause Mortality
COVID-19 Severity: improves
Length of hospitalization: improves

COVID-19: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
All-Cause Mortality No effect		NoneNo effect	1 study	5,806 people
COVID-19 Severity	Improves (the measure goes down)		3 studies	385 people
Length of hospitalization	Improves (the measure goes down)		2 studies	944 people
Need for mechanical ventilation	Changes; see studies		2 studies	2,435 people
C-Reactive Protein (CRP)	Improves (the measure goes down)			1,492 people
Ferritin	Improves (the measure goes up)			1,492 people
Hemoglobin	Improves (the measure goes up)			1,492 people
intensive care unit admission risk	Changes; see studies			4,936 people
intubation risk	Changes; see studies			4,936 people
Lymphocyte Count	Improves (the measure goes up)			1,492 people
Neutrophil Count	Improves (the measure goes up)			1,492 people
Serum Platelets	Improves (the measure goes up)			447 people

Irritable Bowel Syndrome (IBS)

Irritable Bowel Syndrome Symptoms
Plasma Vitamin D: improves
Quality of Life: improves

Irritable Bowel Syndrome (IBS): outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Irritable Bowel Syndrome Symptoms No effect		NoneNo effect	1 study	685,802 people
Plasma Vitamin D	Improves (the measure goes up)			780 people
Quality of Life	Improves (the measure goes up)			685,802 people

Pneumonia

Pneumonia Symptoms
Upper Respiratory Tract Infection Risk: changes; see studies
Upper Respiratory Tract Infection Symptoms: improves

Pneumonia: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Pneumonia Symptoms No effect		NoneNo effect	1 study	653 people
Upper Respiratory Tract Infection Risk	Changes; see studies		13 studies	453 people
Upper Respiratory Tract Infection Symptoms	Improves (the measure goes down)		13 studies	453 people

Cardiovascular Disease

All-Cause Mortality
Risk Of Cardiovascular Disease: improves

Cardiovascular Disease: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	All-Cause Mortality No effect		NoneNo effect	1 study	3,258 people
	Risk Of Cardiovascular Disease	Improves (the measure goes down)		3 studies	3,258 people

Chronic Liver Disease

All-Cause Mortality
Insulin: changes; see studies
Insulin Resistance: improves

Chronic Liver Disease: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
All-Cause Mortality No effect		NoneNo effect	1 study	4,084 people
Insulin	Changes; see studies		3 studies	4,084 people
Insulin Resistance	Improves (the measure goes down)		1 study	4,084 people
Liver Enzymes	Changes; see studies		1 study	4,084 people
High-density lipoprotein (HDL)	Improves (the measure goes up)			4,084 people
Liver Fat	Improves (the measure goes down)			4,084 people
Liver Fibrosis	Improves (the measure goes down)			4,084 people
Triglycerides	Improves (the measure goes down)			4,084 people

Obesity

Arterial Stiffness
Glycemic Control: improves
Insulin: changes; see studies

Obesity: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Arterial Stiffness No effect		NoneNo effect		225 people
Glycemic Control	Improves (the measure goes up)		4 studies	112 people
Insulin	Changes; see studies		3 studies	1 person
Low-density lipoprotein (LDL)	Improves (the measure goes down)		3 studies	70 people
Blood glucose	Improves (the measure goes down)		2 studies	1 person
Blood Pressure	Improves (the measure goes down)		2 studies	225 people
Inflammation	Improves (the measure goes down)		2 studies	225 people
Weight	Improves (the measure goes down)		2 studies	307 people
HbA1c	Improves (the measure goes down)		1 study	1 person
Insulin Resistance	Improves (the measure goes down)		1 study	1 person
Muscle Mass	Improves (the measure goes up)		1 study	100 people
Parathyroid Hormone	Improves (the measure goes up)		1 study	100 people
Type 2 Diabetes Incidence	Changes; see studies		1 study	27,425 people
Body Fat	Improves (the measure goes down)			184 people
Body Mass Index (BMI)	Improves (the measure goes down)			337 people
Food Intake	Changes; see studies			77 people
High-density lipoprotein (HDL)	Improves (the measure goes up)			70 people
Pulse Wave Velocity	Improves (the measure goes down)			225 people
Total cholesterol	Improves (the measure goes down)			1 person
Triglycerides	Improves (the measure goes down)			93 people
Vascular Function	Improves (the measure goes up)			225 people
Waist circumference	Improves (the measure goes down)			290 people

Overweight

Arterial Stiffness
Glycemic Control: improves
Insulin: changes; see studies

Overweight: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Arterial Stiffness No effect		NoneNo effect		225 people
Glycemic Control	Improves (the measure goes up)		4 studies	89 people
Insulin	Changes; see studies		3 studies	181 people
Low-density lipoprotein (LDL)	Improves (the measure goes down)		3 studies	70 people
Blood glucose	Improves (the measure goes down)		2 studies	225 people
Blood Pressure	Improves (the measure goes down)		2 studies	225 people
Inflammation	Improves (the measure goes down)		2 studies	225 people
Weight	Improves (the measure goes down)		2 studies	307 people
HbA1c	Improves (the measure goes down)		1 study	92 people
Insulin Resistance	Improves (the measure goes down)		1 study	225 people
Muscle Mass	Improves (the measure goes up)		1 study	77 people
Parathyroid Hormone	Improves (the measure goes up)		1 study	77 people
Testosterone	Improves (the measure goes up)		1 study	165 people
Body Fat	Improves (the measure goes down)			184 people
Body Mass Index (BMI)	Improves (the measure goes down)			337 people
Food Intake	Changes; see studies			77 people
High-density lipoprotein (HDL)	Improves (the measure goes up)			70 people
Pulse Wave Velocity	Improves (the measure goes down)			225 people
Triglycerides	Improves (the measure goes down)			93 people
Vascular Function	Improves (the measure goes up)			225 people
Waist circumference	Improves (the measure goes down)			290 people

Asthma

Acute Respiratory Tract Infection Symptoms
Upper Respiratory Tract Infection Risk: changes; see studies
Upper Respiratory Tract Infection Symptoms: improves

Asthma: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Acute Respiratory Tract Infection Symptoms No effect		NoneNo effect		2,461 people
Upper Respiratory Tract Infection Risk	Changes; see studies		13 studies	3,958 people
Upper Respiratory Tract Infection Symptoms	Improves (the measure goes down)		13 studies	658 people
Asthma Symptoms	Improves (the measure goes down)		2 studies	2,461 people
Allergy Symptoms	Improves (the measure goes down)			2,461 people
Eczema Symptoms	Improves (the measure goes down)			2,461 people
Immunoglobulin E	Improves (the measure goes up)			2,461 people
Lung Function	Improves (the measure goes up)			156 people

Prediabetes

Beta-cell function
Glycemic Control: improves
Insulin: changes; see studies

Prediabetes: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Beta-cell function No effect		NoneNo effect		66 people
Glycemic Control	Improves (the measure goes up)		4 studies	97 people
Insulin	Changes; see studies		3 studies	89 people
Insulin Resistance	Improves (the measure goes down)		1 study	66 people
Type 2 Diabetes Incidence	Changes; see studies		1 study	27,425 people

Infertility

Seminal Motility
Sperm Count: improves
Testosterone: improves

Infertility: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Seminal Motility No effect		NoneNo effect
Sperm Count	Improves (the measure goes up)		1 study
Testosterone	Improves (the measure goes up)		1 study	449 people
Sex Hormone Binding Globulin	Improves (the measure goes up)			449 people
Sperm Quality	Improves (the measure goes up)

Lower Respiratory Tract Infection

Lower Respiratory Tract Infection Risk
Upper Respiratory Tract Infection Risk: changes; see studies
Upper Respiratory Tract Infection Symptoms: improves

Lower Respiratory Tract Infection: outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Lower Respiratory Tract Infection Risk No effect		NoneNo effect		5,110 people
Upper Respiratory Tract Infection Risk	Changes; see studies		13 studies	10,220 people
Upper Respiratory Tract Infection Symptoms	Improves (the measure goes down)		13 studies	156 people

Eczema (Atopic Dermatitis)

Acute Respiratory Tract Infection Symptoms
Asthma Symptoms: improves
Allergy Symptoms: improves

Eczema (Atopic Dermatitis): outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Acute Respiratory Tract Infection Symptoms No effect		NoneNo effect		2,461 people
Asthma Symptoms	Improves (the measure goes down)		2 studies	2,461 people
Allergy Symptoms	Improves (the measure goes down)			2,461 people
Eczema Symptoms	Improves (the measure goes down)			2,461 people
Immunoglobulin E	Improves (the measure goes up)			2,461 people

Osteoarthritis (OA)

Collagen Content
Pain: improves
Osteoarthritis Symptoms: improves

Osteoarthritis (OA): outcomes studied for Vitamin D
Outcome	Effect	Size	Studies	People
Collagen Content No effect		NoneNo effect		146 people
Pain	Improves (the measure goes down)		2 studies	146 people
Osteoarthritis Symptoms	Improves (the measure goes down)			146 people

Respiratory Health

Lower Respiratory Tract Infection Risk
Upper Respiratory Tract Infection Risk: changes; see studies

Respiratory Health: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Lower Respiratory Tract Infection Risk No effect		NoneNo effect		5,724 people
	Upper Respiratory Tract Infection Risk	Changes; see studies		13 studies	5,724 people

Multiple Sclerosis (MS)

Multiple Sclerosis Symptoms: improves

Multiple Sclerosis (MS): outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Multiple Sclerosis Symptoms	Improves (the measure goes down)		6 studies	719 people

Fibromyalgia

Fibromyalgia Symptoms: improves

Fibromyalgia: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Fibromyalgia Symptoms	Improves (the measure goes down)		4 studies	176 people

Pain: improves

High Blood Pressure

Blood Pressure: improves

High Blood Pressure: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Blood Pressure	Improves (the measure goes down)		2 studies	545 people

Traumatic Brain Injury

Inflammation: improves

Traumatic Brain Injury: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Inflammation	Improves (the measure goes down)		2 studies	35 people

Graves’ Disease

Bone Mineral Density: improves

Graves’ Disease: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Bone Mineral Density	Improves (the measure goes up)		2 studies	86 people

Acne

Acne Symptoms: improves

Acne: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Acne Symptoms	Improves (the measure goes down)		1 study	44 people

Alzheimer’s Disease

Alzheimer's Disease Symptoms: improves

Alzheimer’s Disease: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Alzheimer's Disease Symptoms	Improves (the measure goes down)		1 study	210 people

Chronic Obstructive Pulmonary Disease (COPD)

Cathelicidin: improves

Chronic Obstructive Pulmonary Disease (COPD): outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Cathelicidin	Improves (the measure goes up)		1 study	23 people

Low Testosterone

Testosterone: improves

Low Testosterone: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Testosterone	Improves (the measure goes up)		1 study	165 people

Type 1 Diabetes

Type 1 Diabetes Incidence: changes; see studies

Type 1 Diabetes: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Type 1 Diabetes Incidence	Changes; see studies		1 study	51 people

Cystic Fibrosis

Bone turnover markers: changes; see studies

Cystic Fibrosis: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Bone turnover markers	Changes; see studies		1 study	91 people

Diabetic Foot Ulcers

Wound Healing: improves

Diabetic Foot Ulcers: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Wound Healing	Improves (the measure goes up)		1 study

Frailty

Fracture Risk: changes; see studies

Frailty: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Fracture Risk	Changes; see studies		1 study	42,279 people

Longer Lifespan

All-Cause Mortality: improves

Longer Lifespan: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	All-Cause Mortality	Improves (the measure goes down)		1 study	94,148 people

Metabolic Health

HbA1c: improves

Metabolic Health: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	HbA1c	Improves (the measure goes down)		1 study	9 people

Muscle Recovery

Power Output: improves

Muscle Recovery: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Power Output	Improves (the measure goes up)		1 study	20 people

Otitis Media

Otitis Media Risk: changes; see studies

Otitis Media: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Otitis Media Risk	Changes; see studies		1 study	116 people

Pancreatic Cancer

Pancreatic Cancer Risk: changes; see studies

Pancreatic Cancer: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Pancreatic Cancer Risk	Changes; see studies		1 study	46 people

Surgical Recovery

Risk of Hypocalcemia: improves

Surgical Recovery: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Risk of Hypocalcemia	Improves (the measure goes up)		1 study	645 people

Uremic Pruritus

Itching: improves

Uremic Pruritus: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Itching	Improves (the measure goes up)		1 study	1,085 people

Thyroid Cancer

Risk of Hypocalcemia: improves

Thyroid Cancer: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Risk of Hypocalcemia	Improves (the measure goes up)		1 study	645 people

Alzheimer’s Disease

Alzheimer's Disease Symptoms: changes; see studies

Alzheimer’s Disease: outcomes studied for Vitamin D
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Alzheimer's Disease Symptoms	Changes; see studies		1 study	210 people

What the published studies found

6 automated readings

Automated reading of the published studies (Decosa evidence engine), for outcomes Dr. Grey has not graded yet. It is not a Dr. Grey grade and does not change one. How it is read

LDL cholesterol
The best available review (2024, 12 studies) found little or no difference in LDL cholesterol. That review studied patients with obesity or type 2 diabetes. 4 of the 6 studies read agree; 1 found no clear answer, 1 found an improvement. The evidence is limited.
6 studies counted of 9 read: 5 reviews and 1 trial (1,521 people in the trials).
1. Meta-analysis, 2024; 12 studies; patients with obesity or type 2 diabetes: no clear difference (the review the verdict rests on). had no effect on any of the outcomes analyzed Effects of vitamin D supplementation on metabolic syndrome parameters in patients with obesity or diabetes in Brazil, Europe, and the United States: A systematic review and meta-analysisPubMed 38992391
2. Meta-analysis, 2026; 7 studies; patients with metabolic syndrome: no clear difference. no significant differences were observed in Effect of vitamin D supplementation on blood lipids in patients with metabolic syndrome: a meta-analysisPubMed 42004716
3. Meta-analysis, 2021; 9 studies; children and adolescents: no clear difference. did not affect the changes of cardiometabolic risk markers Effect of vitamin D supplementation on markers of cardiometabolic risk in children and adolescents: A meta-analysis of randomized clinical trialsPubMed 34353700
4. Meta-analysis, 2016; 17 studies; patients with type 2 diabetes: improves. significant lowering effect of vitamin D on LDL Effects of vitamin D on serum lipid profile in patients with type 2 diabetes: A meta-analysis of randomized controlled trialsPubMed 27020528
5. Meta-analysis, 2012; 12 studies, 1,346 people: unclear: evidence too weak to tell. Influence of vitamin D supplementation on plasma lipid profiles: a meta-analysis of randomized controlled trialsPubMed 22433171
6. Randomised trial, 2017; 1,521 people: no clear difference. for LDL-C, compared with placebo, was -1.6 Effects of Calcium, Vitamin D, and Hormone Therapy on Cardiovascular Disease Risk Factors in the Women's Health Initiative: A Randomized Controlled TrialPubMed 27926633
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Cardiovascular events
The best available review (2026, 9 studies, 114,379 people) found little or no difference in cardiovascular events. All 5 studies read agree. The evidence is moderate.
5 studies counted of 11 read: 5 reviews.
1. Meta-analysis, 2026; 9 studies, 114,379 people: no clear difference (the review the verdict rests on). vitamin D did not reduce any CVD events Vitamin D supplementation and cardiovascular disease events: a systematic review and pooled meta-analysis of randomized clinical trialsPubMed 41183312
2. Meta-analysis, 2024; 36 studies, 493,389 people: no clear difference. no significant difference between vitamin D supplementation and placebo Cardiovascular and Cerebrovascular Outcomes With Vitamin D Supplementation: A Systematic Review and Meta-AnalysisPubMed 37802169
3. Meta-analysis, 2022: no clear difference. no significant effects on the primary outcomes, including cancer, cardiovascular events Critical Appraisal of Large Vitamin D Randomized Controlled TrialsPubMed 35057483
4. Meta-analysis, 2020; 22 studies, 83,200 people: no clear difference. CHD events (RR 1.00, CI 0.91-1.10) Vitamin D supplementation, cardiac events and stroke: A systematic review and meta-regression analysisPubMed 32462077
5. Meta-analysis, 2019: no clear difference. regarding CVD events and mortality from Vitamin D and Cardiovascular Disease: An UpdatePubMed 31519560
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Mood
The 2 studies read (20,470 people in all) mostly found little or no difference in mood. The evidence is limited.
Side effects: 1 of the 3 studies that reported on them found more with Vitamin D (nephrolithiasis, hypercalcaemia).
2 studies counted of 11 read: 2 trials (20,470 people in the trials).
1. Randomised trial, 2020; 18,353 people; adults aged 50 years or older: no clear difference. mean difference for change in mood scores, 0.01 points Effect 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 TrialPubMed 32749491
2. Randomised trial, 2006; 2,117 people; older women aged 70 years or more: no clear difference. showed there was no significant difference between the two scores Can vitamin D supplementation prevent winter-time blues? A randomised trial among older womenPubMed 16554952
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Respiratory infections
A Cochrane review (2026, 107 studies, 31,521 people) found a small improvement in respiratory infections. That review studied children up to five years of age. 5 of the 8 studies read agree; 2 found no clear difference, 1 found no clear answer. The evidence is limited.
8 studies counted of 10 read: 5 reviews and 3 trials (540 people in the trials).
1. Meta-analysis, 2026; 107 studies, 31,521 people; children up to five years of age: improves (the review the verdict rests on). slight reduction in the proportion of children who make ARI-related healthcare visits Vitamin D for preventing acute respiratory infections in children up to five years of agePubMed 42037591
2. Meta-analysis, 2025; 40 studies, 61,589 people: no clear difference. did not statistically significantly affect overall ARI risk Vitamin D supplementation to prevent acute respiratory infections: systematic review and meta-analysis of stratified aggregate dataPubMed 39993397
3. Meta-analysis, 2025; 37 studies, 16,000 people: unclear: evidence too weak to tell. SOR was 0.92 (0.86-0.99) for all trials Vitamin D, acute respiratory infections, and Covid-19: The curse of small-size randomised trials. A critical review with meta-analysis of randomised trialsPubMed 39808630
4. Systematic review, 2025; 38 studies; offspring of mothers given vitamin D in pregnancy: improves. vitamin D supplementation reduced respiratory tract infections Effects of Maternal Vitamin D Supplementation on Childhood HealthPubMed 41129483
5. Meta-analysis, 2016; 4 studies, 3,198 people; children under five years of age: no clear difference. episodes of 'radiologically confirmed' first or only episode of pneumonia were little different Vitamin D supplementation for preventing infections in children under five years of agePubMed 27826955
6. Randomised trial, 2026; 80 people; ICU patients with traumatic lung contusion, VAP, sepsis: improves. faster recovery from lung contusion, VAP, and sepsis Effect of vitamin D as Nutrition Supplement on Patients with Prolonged Ventilation due to Ventilator Associated Pneumonia and Sepsis Followed Severe Traumatic Lung Contusion: A Randomized Controlled TrialPubMed 41525115
7. Randomised trial, 2025; 200 people; healthy 6-8-year-old children: improves. had 17% fewer sick days due to ARTI Effects of vitamin D supplementation on acute respiratory tract infections in 6-8-year-old children: a randomized clinical trialPubMed 40310565
8. Randomised trial, 2015; 260 people; pregnant women and their infants: improves. proportion of children making any ARI visits was smaller in the higher-dose Reduced primary care respiratory infection visits following pregnancy and infancy vitamin D supplementation: a randomised controlled trialPubMed 25283480
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Sleep quality
The best available review (2022, 19 studies) found an improvement in sleep quality. 7 of the 8 studies read agree; 1 found a worse result. The evidence is moderate.
Possible harm: 1 study read reported a worse result for sleep quality with Vitamin D. One abstract says: "overall worse sleep quality (ptrend<0.01). Women who became vitamin D replete (≥32ng/mL) also showed a deterioration in total PSQI sleep quality score" Check the studies below, and ask a doctor or pharmacist if this applies to you.
8 studies counted of 10 read: 5 reviews and 3 trials (301 people in the trials).
1. Meta-analysis, 2022; 19 studies: improves (the review the verdict rests on). statistically significant decrease in the Pittsburgh Sleep Quality Index Vitamin D Supplementation and Sleep: A Systematic Review and Meta-Analysis of Intervention StudiesPubMed 35268051
2. Meta-analysis, 2022; 31 studies: improves. Efficacy of dietary supplements on improving sleep quality: a systematic review and meta-analysisPubMed 33441476
3. Meta-analysis, 2022; 5 studies; people with poor sleep quality: improves. significantly improves sleep quality (MD: -1.32; 95%CI: -2.55 to -0.09; P = 0.04) The effect of vitamin D on sleep quality: A systematic review and meta-analysisPubMed 35578558
4. Meta-analysis, 2020; people with sleep disorders: improves. A meta-analysis: Does vitamin D play a promising role in sleep disorders?PubMed 33133571
5. Meta-analysis, 2019; 2 studies; patients with psychiatric disorders: improves. The effects of vitamin D supplementation on mental health, and biomarkers of inflammation and oxidative stress in patients with psychiatric disorders: A systematic review and meta-analysis of randomized controlled trialsPubMed 31095994
6. Randomised trial, 2024; 212 people; chinese individuals with prediabetes: improves. total PSQI score in vitamin D + calcium group was lower Effects of vitamin D and/or calcium intervention on sleep quality in individuals with prediabetes: a post hoc analysis of a randomized controlled trialPubMed 38366270
7. Randomised trial, 2018; 89 people; 20-50 year-old people with sleep disorders: improves. sleep score (PSQI) reduced significantly in vitamin recipients The effect of vitamin D supplement on the score and quality of sleep in 20-50 year-old people with sleep disorders compared with control groupPubMed 28475473
8. Randomised trial, 2016; overweight postmenopausal women with low vitamin D: worsens. deterioration in total PSQI sleep quality score Repletion of vitamin D associated with deterioration of sleep quality among postmenopausal womenPubMed 27687537
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Stress
The best available review (2024, 6 studies, 445 people) found an improvement in stress. That review studied iranian women with polycystic ovary syndrome. 4 of the 6 studies read agree; 2 found no clear answer. The evidence is moderate.
6 studies counted of 11 read: 6 reviews.
1. Meta-analysis, 2024; 6 studies, 445 people; iranian women with polycystic ovary syndrome: improves (the review the verdict rests on). Vitamin D effectively reduced malondialdehyde (P=0.002) Effects of vitamin D supplementation on oxidative stress biomarkers of Iranian women with polycystic ovary syndrome: a meta-analysis studyPubMed 38994457
2. Systematic review, 2023; 11 studies; people undergoing exercise-induced muscle damage: unclear: evidence too weak to tell. effects on muscle function, muscle pain and oxidative stress need to be confirmed Effects of vitamin D supplementation on muscle function and recovery after exercise-induced muscle damage: A systematic reviewPubMed 36149089
3. Meta-analysis, 2022; 23 studies: improves. Efficacy of vitamin D supplementation as an adjunct therapy for improving inflammatory and oxidative stress biomarkers: An umbrella meta-analysisPubMed 36206958
4. Meta-analysis, 2021; 18 studies, 1,060 people; patients with polycystic ovary syndrome: improves. Vitamin D improves levels of hormonal, oxidative stress and inflammatory parameters in polycystic ovary syndrome: a meta-analysis studyPubMed 33545754
5. Systematic review, 2019: unclear: evidence too weak to tell. controversial effects about the ability of cholecalciferol The controversial role of vitamin D as an antioxidant: results from randomised controlled trialsPubMed 30326975
6. Meta-analysis, 2018; 7 studies; women with polycystic ovary syndrome: improves. The Effects of Vitamin D Supplementation on Biomarkers of Inflammation and Oxidative Stress Among Women with Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled TrialsPubMed 29475212
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.

Key findings

Fall RiskFall PreventionImproves (the measure goes down)
Pre-Eclampsia RiskPreeclampsiaImproves (the measure goes down)
Depression SymptomsVitamin D DeficiencyImproves (the measure goes down)

Shop the evidence-backed picks

Fullscript collections

Fullscript collectionStress and mood: evidence-graded picksOpen on Fullscript Fullscript collectionMuscle, performance and healthy ageing: evidence-graded picksOpen on Fullscript Fullscript collectionJoints and bones: evidence-graded picksOpen on Fullscript Fullscript collectionImmune support: evidence-graded picksOpen on Fullscript

Each collection holds the supplements we grade A or B for its theme, in third-party tested products where the catalog has them. It opens in our Fullscript store. You can look through it without signing in; Fullscript asks for a free account to order.

Or shop one supplement

Third-party tested Vitamin D products, in the forms the graded studies used where we can match them.

Grade A

We earn from purchases made in our Fullscript store, and links to Fullscript, iHerb or Thorne carry our referral, so we may earn a commission at no extra cost to you. Grades come from the research and never change based on what we earn. Full disclosure

Studies cited

100 studies from PubMed

Effect of vitamin D supplementation for major adverse cardiovascular events: a meta-analysis based on randomised controlled trials.Br J Nutr, 2025 · PMID 40685646
Optimal Vitamin D Status: Evidence and GuidelinesEndocr Connect, 2019 · PMID 30697582
Vitamin D and Cancer Prevention: A Comprehensive ReviewNat Rev Cancer, 2019 · PMID 30612257
Effects of Vitamin D Supplementation on Musculoskeletal Health: A Systematic Review and Meta-AnalysisLancet Diabetes Endocrinol, 2018 · PMID 30445434
Vitamin D and Prevention of Respiratory Tract Infections: A Systematic Review and Meta-AnalysisBMJ, 2018 · PMID 29878139
Effects of Vitamin D Supplementation on Depression: A Systematic Review and Meta-AnalysisNutrients, 2018 · PMID 29481980
Vitamin D and Immune Function: A ReviewJ Investig Med, 2018 · PMID 30125852
Vitamin D Supplementation for Prevention of Mortality: A Meta-AnalysisCochrane Database Syst Rev, 2018 · PMID 29789217
Vitamin D Supplementation During Pregnancy: Safety and Efficacy ReviewNutr Rev, 2018 · PMID 29459995
Vitamin D Supplementation: A Comprehensive Review of Efficacy for Various Health OutcomesLancet Diabetes Endocrinol, 2017 · PMID 28768407
Vitamin D Deficiency: Global Health PerspectiveMed Clin North Am, 2017 · PMID 27986512
Vitamin D and Cardiovascular Disease: A Review of EvidenceAnn Intern Med, 2017 · PMID 28440249
Vitamin D and Bone Health in Adults: A Systematic ReviewLancet, 2017 · PMID 28212022
Vitamin D3 supplementation does not modify cardiovascular risk profile of adults with inadequate vitamin D statusEur J Nutr, 2015 · PMID 26621634
Association of A1C levels with vitamin D status in U.S. adults: data from the National Health and Nutrition Examination SurveyDiabetes Care, 2010 · PMID 20215453
Serum 25-hydroxyvitamin D, ethnicity, and blood pressure in the Third National Health and Nutrition Examination SurveyAm J Hypertens, 2007 · PMID 17586404
Effects of selected dietary supplements on migraine prophylaxis: A systematic review and dose-response meta-analysis of randomized controlled trials.Neurol Sci · PMID 39404918
Safety, tolerability, and efficacy of orally administered cannabinoids in MSNeurology · PMID 12011290
Smoked cannabis for spasticity in multiple sclerosis: a randomized, placebo-controlled trialCMAJ · PMID 22586334
The effect of cannabis on tremor in patients with multiple sclerosisNeurology · PMID 15079008
Supplementation with vitamin D or ω-3 fatty acids in adolescent girls and young women with endometriosis (SAGE): a double-blind, randomized, placebo-controlled trialAm J Clin Nutr · PMID 32453393
Double-blind randomised placebo-controlled trial of bolus-dose vitamin D3 supplementation in adults with asthma (ViDiAs)Thorax · PMID 25724847
Vitamin D Supplementation and the Risk of Colds in Patients with AsthmaAm J Respir Crit Care Med · PMID 26540136
Association between prenatal vitamin D supplementation and respiratory diseases in children: a systematic review and meta-analysis.BMC Pediatr · PMID 41204244
Vitamin D supplementation decrease asthma exacerbations in children: a systematic review and meta-analysis of randomized controlled trials.Ann Med · PMID 39421966
The effects of prenatal vitamin D supplementation on respiratory and allergy-related outcomes in children: A systematic review and meta-analysis of randomized controlled trials.World Allergy Organ J · PMID 40535465
Effects of Vitamin D on Endometriosis-Related Pain: A Double-Blind Clinical TrialMed Sci Monit · PMID 27986972
The effect of vitamin D supplementation on clinical symptoms and metabolic profiles in patients with endometriosisGynecol Endocrinol · PMID 33508990
Vitamin D for primary dysmenorrhea and endometriosis-related pain - A systematic review of registered RCTs.PLoS One · PMID 40257970
High-Dose Monthly Vitamin D for Prevention of Acute Respiratory Infection in Older Long-Term Care Residents: A Randomized Clinical TrialJ Am Geriatr Soc · PMID 27861708
Randomized trial of vitamin D supplementation and risk of acute respiratory infection in MongoliaPediatrics · PMID 22908115
Reduced primary care respiratory infection visits following pregnancy and infancy vitamin D supplementation: a randomised controlled trialActa Paediatr · PMID 25283480
Vitamin D supplementation to prevent acute respiratory infections: individual participant data meta-analysisHealth Technol Assess · PMID 30675873
Therapeutic effect of vitamin D3 in multiple sclerosis patientsImmunol Invest · PMID 21542721
Effect of vitamin D3 supplementation on relapses, disease progression, and measures of function in persons with multiple sclerosis: exploratory outcomes from a double-blind randomised controlled trialMult Scler · PMID 22354743
Relationship between 25-OH-D serum level and relapse rate in multiple sclerosis patients before and after vitamin D supplementationTher Adv Neurol Disord · PMID 22783368
Randomized trial of daily high-dose vitamin D 3 in patients with RRMS receiving subcutaneous interferon β-1aNeurology · PMID 31594857
Cholecalciferol in relapsing-remitting MS: A randomized clinical trial (CHOLINE)Neurol Neuroimmunol Neuroinflamm · PMID 31454777
Effects of adjunct low-dose vitamin d on relapsing-remitting multiple sclerosis progression: preliminary findings of a randomized placebo-controlled trialMult Scler Int · PMID 22567287
Vitamin D supplementation and upper respiratory tract infections in adolescent swimmers: a randomized controlled trialPediatr Exerc Sci · PMID 25050610
Effect of vitamin D3 supplementation on upper respiratory tract infections in healthy adults: the VIDARIS randomized controlled trialJAMA · PMID 23032549
Vitamin D3 and gargling for the prevention of upper respiratory tract infections: a randomized controlled trialBMC Infect Dis · PMID 24885201
Intake of 25-Hydroxyvitamin D3 Reduces Duration and Severity of Upper Respiratory Tract Infection: A Randomized, Double-Blind, Placebo-Controlled, Parallel Group Comparison StudyJ Nutr Health Aging · PMID 29582888
Vitamin D₃ Supplementation Reduces the Symptoms of Upper Respiratory Tract Infection during Winter Training in Vitamin D-Insufficient Taekwondo Athletes: A Randomized Controlled TrialInt J Environ Res Public Health · PMID 30223447
A randomized controlled trial of vitamin D3 supplementation for the prevention of symptomatic upper respiratory tract infectionsEpidemiol Infect · PMID 19296870
Vitamin D supplementation for the prevention of acute respiratory tract infection: a randomized, double-blinded trial among young Finnish menJ Infect Dis · PMID 20632889
Effect of High-Dose vs Standard-Dose Wintertime Vitamin D Supplementation on Viral Upper Respiratory Tract Infections in Young Healthy ChildrenJAMA · PMID 28719693
Vitamin D supplementation to prevent infections: a sub-study of a randomised placebo-controlled trial in older people (RECORD trial, ISRCTN 51647438)Age Ageing · PMID 17702768
Vitamin D3 supplementation and upper respiratory tract infections in a randomized, controlled trialClin Infect Dis · PMID 24014734
Effect of monthly high-dose vitamin D supplementation on acute respiratory infections in older adults: A randomized controlled trialClin Infect Dis · PMID 31420647
Vitamin D3 supplementation in patients with frequent respiratory tract infections: a randomised and double-blind intervention studyBMJ Open · PMID 23242238
Effect of Vitamin D supplementation to reduce respiratory infections in children and adolescents in Vietnam: A randomized controlled trialInfluenza Other Respir Viruses · PMID 30328294
Winter cholecalciferol supplementation at 55°N has little effect on markers of innate immune defense in healthy children aged 4-8 years: a secondary analysis from a randomized controlled trialEur J Nutr · PMID 29572676
Vitamin D supplementation enhances the beneficial effects of weight loss on cardiovascular disease risk markersAm J Clin Nutr · PMID 19321573
Different doses of supplemental vitamin D maintain interleukin-5 without altering skeletal muscle strength: a randomized, double-blind, placebo-controlled study in vitamin D sufficient adultsNutr Metab · PMID 22405472
Vitamin D, tuberculin skin test conversion, and latent tuberculosis in Mongolian school-age children: a randomized, double-blind, placebo-controlled feasibility trialAm J Clin Nutr · PMID 22760564
Double-blind randomised controlled trial of vitamin D3 supplementation for the prevention of acute respiratory infection in older adults and their carers (ViDiFlu)Thorax · PMID 26063508
Effects of vitamin D supplementation to children diagnosed with pneumonia in Kabul: a randomised controlled trialTrop Med Int Health · PMID 20723187
Vitamin D supplementation for severe pneumonia--a randomized controlled trialIndian Pediatr · PMID 21992858
Systematic review: Vitamin D and calcium supplementation in prevention of cardiovascular eventsAnn Intern Med · PMID 20194238
Effect of vitamin D supplementation on progression of knee pain and cartilage volume loss in patients with symptomatic osteoarthritis: a randomized controlled trialJAMA · PMID 23299607
Impact of vitamin D supplementation during a resistance training intervention on body composition, muscle function, and glucose tolerance in overweight and obese adultsClin Nutr · PMID 23034474
A randomized, placebo-controlled trial of vitamin D supplementation to improve glycaemia in overweight and obese African AmericansDiabetes Obes Metab · PMID 22486948
A 12-week double-blind randomized clinical trial of vitamin D3 supplementation on body fat mass in healthy overweight and obese womenNutr J · PMID 22998754
Can Vitamin D supplementation enhance the effectiveness of exercise-induced weight loss in overweight or obese adults? Evidence from integrated transcriptomic and meta-analysisFront Nutr · PMID 41098796
Effect of vitamin D supplementation on body composition, lipid profile, and glycemic indices in patients with obesity-associated metabolic syndrome: a systematic review and meta-analysis.Diabetol Metab Syndr · PMID 40682197
Effect of vitamin D3 supplementation on vascular and metabolic health of vitamin D-deficient overweight and obese children: a randomized clinical trial.Am J Clin Nutr · PMID 31950134
Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial.Nat Commun · PMID 40199888
Effects of vitamin D on patients with fibromyalgia syndrome: a randomized placebo-controlled trialPain · PMID 24438771
Vitamin D Supplementation Seems to Improve Fibromyalgia Symptoms: Preliminary ResultsIsr Med Assoc J · PMID 29911760
Effects of Vitamin D Therapy on Quality of Life in Patients with FibromyalgiaEurasian J Med · PMID 28638253
Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildrenAm J Clin Nutr · PMID 20219962
Preventive Effects of Vitamin D on Seasonal Influenza A in Infants: A Multicenter, Randomized, Open, Controlled Clinical TrialPediatr Infect Dis J · PMID 29315160
Vitamin D supplementation did not prevent influenza-like illness as diagnosed retrospectively by questionnaires in subjects participating in randomized clinical trialsScand J Infect Dis · PMID 22026455
Effects of vitamin D supplements on influenza A illness during the 2009 H1N1 pandemic: a randomized controlled trialFood Funct · PMID 25088394
Effects of vitamin D and calcium supplementation on pancreatic β cell function, insulin sensitivity, and glycemia in adults at high risk of diabetes: the Calcium and Vitamin D for Diabetes Mellitus (CaDDM) randomized controlled trialAm J Clin Nutr · PMID 21715514
Effect of vitamin D supplementation on testosterone levels in menHorm Metab Res · PMID 21154195
Independent association of low serum 25-hydroxyvitamin d and 1,25-dihydroxyvitamin d levels with all-cause and cardiovascular mortalityArch Intern Med · PMID 18574092
Effect of a Single High Dose of Vitamin D3 on Hospital Length of Stay in Patients With Moderate to Severe COVID-19: A Randomized Clinical TrialJAMA · PMID 33595634
Effects of a 2-Week 5000 IU versus 1000 IU Vitamin D3 Supplementation on Recovery of Symptoms in Patients with Mild to Moderate Covid-19: A Randomized Clinical TrialNutrients · PMID 34202578
"Effect of calcifediol treatment and best available therapy versus best available therapy on intensive care unit admission and mortality among patients hospitalized for COVID-19: A pilot randomized clinical study"J Steroid Biochem Mol Biol · PMID 32871238
Therapeutic effects of vitamin D supplementation on COVID-19 aggravation: a systematic review and meta-analysis of randomized controlled trials.Front Pharmacol · PMID 38860175
Vitamin D supplementation for managing COVID-19 in patients with vitamin D deficiency: a systematic review and meta-analysis of randomised controlled trials.BMJ Open · PMID 40139702
Effect of vitamin D supplementation on clinical outcomes in adult patients with COVID-19: A GRADE-assessed systematic review and meta-analysis of randomized controlled trials.Pharmacol Res Perspect · PMID 39350561
The Effect of Vitamin D Supplementation Post COVID-19 Infection and Related Outcomes: A Systematic Review and Meta-Analysis.Nutrients · PMID 39599582
Vitamin D and prevention of breast cancer: pooled analysisJ Steroid Biochem Mol Biol · PMID 17368188
Association between plasma 25-hydroxyvitamin D and breast cancer riskCancer Prev Res · PMID 19470790
Effect of vitamin D supplementation on serum 25-hydroxy vitamin D levels, joint pain, and fatigue in women starting adjuvant letrozole treatment for breast cancerBreast Cancer Res Treat · PMID 19655244
A prospective randomized controlled trial of the effects of vitamin D supplementation on cardiovascular disease riskPLoS One · PMID 22586483
The effect of vitamin D supplement on the score and quality of sleep in 20-50 year-old people with sleep disorders compared with control groupNutr Neurosci · PMID 28475473
Correlation of symptoms with vitamin D deficiency and symptom response to cholecalciferol treatment: a randomized controlled trialEndocr Pract · PMID 19364687
Efficacy of vitamin D supplementation on depressive symptoms in older patients: a meta-analysis of randomized controlled trials.Front Med · PMID 39450108
Effect of vitamin D supplementation, directly or via breast milk for term infants, on serum 25 hydroxyvitamin D and related biochemistry, and propensity to infection: a randomised placebo-controlled trialBr J Nutr · PMID 27184759
Supplementation with 1000 IU vitamin D/d leads to parathyroid hormone suppression, but not increased fractional calcium absorption, in 4-8-y-old children: a double-blind randomized controlled trialAm J Clin Nutr · PMID 23151536
Prevention of nonvertebral fractures with oral vitamin D and dose dependency: a meta-analysis of randomized controlled trialsArch Intern Med · PMID 19307517
Changes in bone turnover after high-dose vitamin D supplementation during acute pulmonary exacerbation in cystic fibrosis.Bone · PMID 37390941
Vitamin D Supplementation for Premenstrual Syndrome-Related inflammation and antioxidant markers in students with vitamin D deficient: a randomized clinical trialSci Rep · PMID 31624297
The Effect of Vitamin D Supplement Consumption on Premenstrual Syndrome in Vitamin D-Deficient Young Girls: A Randomized, Double-Blind, Placebo-Controlled Clinical TrialComplement Med Res · PMID 31104056
Vitamin D Supplementation for Premenstrual Syndrome-Related Mood Disorders in Adolescents with Severe Hypovitaminosis DJ Pediatr Adolesc Gynecol · PMID 26724745
High dose vitamin D supplementation can improve menstrual problems, dysmenorrhea, and premenstrual syndrome in adolescentsGynecol Endocrinol · PMID 29447494

Evidence by condition

General Cardiovascular Health

Muscle Size Strength

Graves’ Disease

Alzheimer’s Disease

What the published studies found

LDL cholesterol

Cardiovascular events

Mood

Respiratory infections

Sleep quality

Stress

Key findings

Shop the evidence-backed picks

Studies cited

Related supplements

Protocols that include Vitamin D