Vitamin D

Last Updated: September 28 2022

Vitamin D is a fat-soluble vitamin that our skin synthesizes when exposed to the sun. It benefits us in many ways, from bone health to mood.

Vitamin D is most often used for

What is vitamin D?

Vitamin D is a fat-soluble nutrient. It is one of the 24 micronutrients critical for human survival. The sun is the major natural source through eliciting vitamin D production in the skin, but vitamin D is also found naturally in oily fish and eggs and is added to milk and milk alternatives.

What are vitamin D’s main benefits?

Supplemental vitamin D is associated with a range of benefits, including improved immune health, bone health, and well-being. Supplementation may also reduce the risk of cancer mortality, diabetes, and multiple sclerosis.

The effects of vitamin D likely depend on a person’s circulating levels of 25-hydroxyvitamin D (25(OH)D; a form of vitamin D that is measured in blood samples to determine vitamin D status), and many of its benefits will only be seen when a deficiency is reversed.

What are vitamin D’s main drawbacks?

Extremely high doses of vitamin D can lead to vitamin D toxicity, which causes hypercalcemia (excess calcium in the blood) and can result in a wide variety of health problems. Vitamin D supplementation may also have risks independent of vitamin D toxicity. A few trials on older adults have found that vitamin D increased the risk of falling,[1][2] and one study observed a decrease in bone mineral density among women taking high doses of vitamin D.[3]

How does vitamin D work?

Vitamin D exerts its effects by binding to and activating the vitamin D receptor (VDR). VDR is located inside various cells, and its activation can lead to a change in the expression of dozens, if not hundreds, of genes.

What else is Vitamin D known as?
Note that Vitamin D is also known as:
  • Cholecalciferol (Vitamin D3)
  • Ergocalciferol (Vitamin D2)
Vitamin D should not be confused with:
  • Calcitriol or 1
  • 25-Dihydroxyvitamin D (Hormonally active yet not directly supplemented form)
Dosage information

The recommended daily allowance for Vitamin D is currently set at 400–800 IU/day, but this may be too low for many adults. For moderate supplementation, a 1,000–2,000 IU dose of vitamin D3 is sufficient to meet the needs of most of the population. Higher daily doses are in the range of 20–80 IU per kilogram of body weight.

The Upper Tolerable Intake Level in the United States and Canada is 4,000 IU per day (IU/day). It’s been suggested that the true Upper Tolerable Intake Level may actually be as high as 10,000 IU/day, but there are limited data on health outcomes using doses near this amount.

Vitamin D3 supplementation (cholecalciferol) is recommended over D2 supplementation (ergocalciferol) because D3 tends to raise blood levels more effectively.

Vitamin D should be taken daily, with meals or a source of fat.

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1.^Bischoff-Ferrari HA, Dawson-Hughes B, Orav EJ, Staehelin HB, Meyer OW, Theiler R, Dick W, Willett WC, Egli AMonthly High-Dose Vitamin D Treatment for the Prevention of Functional Decline: A Randomized Clinical TrialJAMA Intern Med.(2016 Feb)
2.^Lawrence J Appel, Erin D Michos, Christine M Mitchell, Amanda L Blackford, Alice L Sternberg, Edgar R Miller 3rd, Stephen P Juraschek, Jennifer A Schrack, Sarah L Szanton, Jeanne Charleston, Melissa Minotti, Sheriza N Baksh, Robert H Christenson, Josef Coresh, Lea T Drye, Jack M Guralnik, Rita R Kalyani, Timothy B Plante, David M Shade, David L Roth, James Tonascia, STURDY Collaborative Research GroupThe Effects of Four Doses of Vitamin D Supplements on Falls in Older Adults : A Response-Adaptive, Randomized Clinical TrialAnn Intern Med.(2021 Feb)
3.^Lauren A Burt, Emma O Billington, Marianne S Rose, Richard Kremer, David A Hanley, Steven K BoydAdverse Effects of High-Dose Vitamin D Supplementation on Volumetric Bone Density Are Greater in Females than MalesJ Bone Miner Res.(2020 Dec)
4.^Wolpowitz D, Gilchrest BAThe vitamin D questions: how much do you need and how should you get itJ Am Acad Dermatol.(2006 Feb)
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8.^Bartolucci G, Giocaliere E, Boscaro F, Vannacci A, Gallo E, Pieraccini G, Moneti GVitamin D3 quantification in a cod liver oil-based supplementJ Pharm Biomed Anal.(2011 Apr 28)
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16.^Prosser DE, Jones GEnzymes involved in the activation and inactivation of vitamin DTrends Biochem Sci.(2004 Dec)
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25.^Manson JE, Rexrode KM, Garland FC, Garland CF, Weinstock MAThe case for a comprehensive national campaign to prevent melanoma and associated mortalityEpidemiology.(2000 Nov)
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28.^Matsuoka LY, Wortsman J, Hollis BWUse of topical sunscreen for the evaluation of regional synthesis of vitamin D3J Am Acad Dermatol.(1990 May)
29.^Matsuoka LY, Ide L, Wortsman J, MacLaughlin JA, Holick MFSunscreens suppress cutaneous vitamin D3 synthesisJ Clin Endocrinol Metab.(1987 Jun)
30.^Matsuoka LY, Wortsman J, Hanifan N, Holick MFChronic sunscreen use decreases circulating concentrations of 25-hydroxyvitamin D. A preliminary studyArch Dermatol.(1988 Dec)
32.^Holick MF, MacLaughlin JA, Clark MB, Holick SA, Potts JT Jr, Anderson RR, Blank IH, Parrish JA, Elias PPhotosynthesis of previtamin D3 in human skin and the physiologic consequencesScience.(1980 Oct 10)
35.^Binkley N, Gemar D, Engelke J, Gangnon R, Ramamurthy R, Krueger D, Drezner MKEvaluation of ergocalciferol or cholecalciferol dosing, 1,600 IU daily or 50,000 IU monthly in older adultsJ Clin Endocrinol Metab.(2011 Apr)
36.^Houghton LA, Vieth RThe case against ergocalciferol (vitamin D2) as a vitamin supplementAm J Clin Nutr.(2006 Oct)
37.^Holick MF, Biancuzzo RM, Chen TC, Klein EK, Young A, Bibuld D, Reitz R, Salameh W, Ameri A, Tannenbaum ADVitamin D2 is as effective as vitamin D3 in maintaining circulating concentrations of 25-hydroxyvitamin DJ Clin Endocrinol Metab.(2008 Mar)
38.^Biancuzzo RM, Young A, Bibuld D, Cai MH, Winter MR, Klein EK, Ameri A, Reitz R, Salameh W, Chen TC, Holick MFFortification of orange juice with vitamin D(2) or vitamin D(3) is as effective as an oral supplement in maintaining vitamin D status in adultsAm J Clin Nutr.(2010 Jun)
39.^Glendenning P, Chew GT, Seymour HM, Gillett MJ, Goldswain PR, Inderjeeth CA, Vasikaran SD, Taranto M, Musk AA, Fraser WDSerum 25-hydroxyvitamin D levels in vitamin D-insufficient hip fracture patients after supplementation with ergocalciferol and cholecalciferolBone.(2009 Nov)
41.^Trang HM, Cole DE, Rubin LA, Pierratos A, Siu S, Vieth REvidence that vitamin D3 increases serum 25-hydroxyvitamin D more efficiently than does vitamin D2Am J Clin Nutr.(1998 Oct)
42.^Armas LA, Hollis BW, Heaney RPVitamin D2 is much less effective than vitamin D3 in humansJ Clin Endocrinol Metab.(2004 Nov)
43.^Romagnoli E, Mascia ML, Cipriani C, Fassino V, Mazzei F, D'Erasmo E, Carnevale V, Scillitani A, Minisola SShort and long-term variations in serum calciotropic hormones after a single very large dose of ergocalciferol (vitamin D2) or cholecalciferol (vitamin D3) in the elderlyJ Clin Endocrinol Metab.(2008 Aug)
44.^Tripkovic L, Lambert H, Hart K, Smith CP, Bucca G, Penson S, Chope G, Hyppönen E, Berry J, Vieth R, Lanham-New SComparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysisAm J Clin Nutr.(2012 Jun)
50.^Visser M, Deeg DJ, Puts MT, Seidell JC, Lips PLow serum concentrations of 25-hydroxyvitamin D in older persons and the risk of nursing home admissionAm J Clin Nutr.(2006 Sep)
51.^Bischoff-Ferrari HA, Giovannucci E, Willett WC, Dietrich T, Dawson-Hughes BEstimation of optimal serum concentrations of 25-hydroxyvitamin D for multiple health outcomesAm J Clin Nutr.(2006 Jul)
52.^Ginde AA, Liu MC, Camargo CA JrDemographic differences and trends of vitamin D insufficiency in the US population, 1988-2004Arch Intern Med.(2009 Mar 23)
53.^Brock K, Huang WY, Fraser DR, Ke L, Tseng M, Stolzenberg-Solomon R, Peters U, Ahn J, Purdue M, Mason RS, McCarty C, Ziegler RG, Graubard BLow vitamin D status is associated with physical inactivity, obesity and low vitamin D intake in a large US sample of healthy middle-aged men and womenJ Steroid Biochem Mol Biol.(2010 Jul)
54.^Tangpricha V, Pearce EN, Chen TC, Holick MFVitamin D insufficiency among free-living healthy young adultsAm J Med.(2002 Jun 1)
56.^Kull M Jr, Kallikorm R, Tamm A, Lember MSeasonal variance of 25-(OH) vitamin D in the general population of Estonia, a Northern European countryBMC Public Health.(2009 Jan 19)
57.^Hovsepian S, Amini M, Aminorroaya A, Amini P, Iraj BPrevalence of vitamin D deficiency among adult population of Isfahan City, IranJ Health Popul Nutr.(2011 Apr)
58.^Levis S, Gomez A, Jimenez C, Veras L, Ma F, Lai S, Hollis B, Roos BAVitamin d deficiency and seasonal variation in an adult South Florida populationJ Clin Endocrinol Metab.(2005 Mar)
59.^van der Mei IA, Ponsonby AL, Engelsen O, Pasco JA, McGrath JJ, Eyles DW, Blizzard L, Dwyer T, Lucas R, Jones GThe high prevalence of vitamin D insufficiency across Australian populations is only partly explained by season and latitudeEnviron Health Perspect.(2007 Aug)
60.^Thomas MK, Lloyd-Jones DM, Thadhani RI, Shaw AC, Deraska DJ, Kitch BT, Vamvakas EC, Dick IM, Prince RL, Finkelstein JSHypovitaminosis D in medical inpatientsN Engl J Med.(1998 Mar 19)
61.^Melamed ML, Michos ED, Post W, Astor B25-hydroxyvitamin D levels and the risk of mortality in the general populationArch Intern Med.(2008 Aug 11)
62.^Vieth R, Bischoff-Ferrari H, Boucher BJ, Dawson-Hughes B, Garland CF, Heaney RP, Holick MF, Hollis BW, Lamberg-Allardt C, McGrath JJ, Norman AW, Scragg R, Whiting SJ, Willett WC, Zittermann AThe urgent need to recommend an intake of vitamin D that is effectiveAm J Clin Nutr.(2007 Mar)
63.^Heaney RP, Davies KM, Chen TC, Holick MF, Barger-Lux MJHuman serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferolAm J Clin Nutr.(2003 Jan)
66.^Mastaglia SR, Mautalen CA, Parisi MS, Oliveri BVitamin D2 dose required to rapidly increase 25OHD levels in osteoporotic womenEur J Clin Nutr.(2006 May)
67.^Corless D, Dawson E, Fraser F, Ellis M, Evans SJ, Perry JD, Reisner C, Silver CP, Beer M, Boucher BJ, et alDo vitamin D supplements improve the physical capabilities of elderly hospital patientsAge Ageing.(1985 Mar)
68.^Cranney A, Weiler HA, O'Donnell S, Puil LSummary of evidence-based review on vitamin D efficacy and safety in relation to bone healthAm J Clin Nutr.(2008 Aug)
69.^Grant WB, Schuitemaker GEHealth benefits of higher serum 25-hydroxyvitamin D levels in The NetherlandsJ Steroid Biochem Mol Biol.(2010 Jul)
70.^Barger-Lux MJ, Heaney RP, Dowell S, Chen TC, Holick MFVitamin D and its major metabolites: serum levels after graded oral dosing in healthy menOsteoporos Int.(1998)
73.^Pepper KJ, Judd SE, Nanes MS, Tangpricha VEvaluation of vitamin D repletion regimens to correct vitamin D status in adultsEndocr Pract.(2009 Mar)
74.^Dawson-Hughes B, Harris SS, Palermo NJ, Ceglia L, Rasmussen HMeal conditions affect the absorption of supplemental vitamin D3 but not the plasma 25-hydroxyvitamin D response to supplementationJ Bone Miner Res.(2013 Aug)
75.^Dawson-Hughes B, Harris SS, Lichtenstein AH, Dolnikowski G, Palermo NJ, Rasmussen HDietary fat increases vitamin D-3 absorptionJ Acad Nutr Diet.(2015 Feb)
77.^Papaioannou A, Kennedy CC, Giangregorio L, Ioannidis G, Pritchard J, Hanley DA, Farrauto L, DeBeer J, Adachi JDA randomized controlled trial of vitamin D dosing strategies after acute hip fracture: no advantage of loading doses over daily supplementationBMC Musculoskelet Disord.(2011 Jun 20)
79.^Kritchevsky SB1, Tooze JA, Neiberg RH, Schwartz GG, Hausman DB, Johnson MA, Bauer DC, Cauley JA, Shea MK, Cawthon PM, Harris TB, Rubin SM, Tylavsky FA, Houston DK; Health ABC Study25-Hydroxyvitamin D, parathyroid hormone, and mortality in black and white older adults: the health ABC studyJ Clin Endocrinol Metab.(2012 Nov)
80.^Smit E, Crespo CJ, Michael Y, Ramirez-Marrero FA, Brodowicz GR, Bartlett S, Andersen REThe effect of vitamin D and frailty on mortality among non-institutionalized US older adultsEur J Clin Nutr.(2012 Jun 13)
81.^Bjelakovic G1, Gluud LL, Nikolova D, Whitfield K, Wetterslev J, Simonetti RG, Bjelakovic M, Gluud CVitamin D supplementation for prevention of mortality in adultsCochrane Database Syst Rev.(2014 Jan 10)
83.^Noordam R, de Craen AJ, Pedram P, Maier AB, Mooijaart SP, van Pelt J, Feskens EJ, Streppel MT, Slagboom PE, Westendorp RG, Beekman M, van Heemst DLevels of 25-hydroxyvitamin D in familial longevity: the Leiden Longevity StudyCMAJ.(2012 Dec 11)
86.^Blomberg Jensen M, Dissing SNon-genomic effects of vitamin D in human spermatozoaSteroids.(2012 Aug)
87.^Nemere I1, Farach-Carson MC, Rohe B, Sterling TM, Norman AW, Boyan BD, Safford SERibozyme knockdown functionally links a 1,25(OH)2D3 membrane binding protein (1,25D3-MARRS) and phosphate uptake in intestinal cellsProc Natl Acad Sci U S A.(2004 May 11)
88.^Sequeira VB1, Rybchyn MS, Tongkao-On W, Gordon-Thomson C, Malloy PJ, Nemere I, Norman AW, Reeve VE, Halliday GM, Feldman D, Mason RSThe role of the vitamin D receptor and ERp57 in photoprotection by 1α,25-dihydroxyvitamin D3Mol Endocrinol.(2012 Apr)
89.^Simpson ER1, Clyne C, Rubin G, Boon WC, Robertson K, Britt K, Speed C, Jones MAromatase--a brief overviewAnnu Rev Physiol.(2002)
90.^Yanase T1, Suzuki S, Goto K, Nomura M, Okabe T, Takayanagi R, Nawata HAromatase in bone: roles of Vitamin D3 and androgensJ Steroid Biochem Mol Biol.(2003 Sep)
91.^Krishnan AV, Swami S, Peng L, Wang J, Moreno J, Feldman DTissue-selective regulation of aromatase expression by calcitriol: implications for breast cancer therapyEndocrinology.(2010 Jan)
93.^Barrera D, Avila E, Hernández G, Halhali A, Biruete B, Larrea F, Díaz LEstradiol and progesterone synthesis in human placenta is stimulated by calcitriolJ Steroid Biochem Mol Biol.(2007 Mar)
94.^Kinuta K, Tanaka H, Moriwake T, Aya K, Kato S, Seino YVitamin D is an important factor in estrogen biosynthesis of both female and male gonadsEndocrinology.(2000 Apr)