Question
Asked 29th Aug, 2014
  • Bethesda, Duisburg, Germany

Is vitamin D a hormone or vitamin?

There have been several reports from Europe and North America stating vitamin D as a hormone or like a hormone. Do you think vitamin D should be concerned as a hormone or vitamin? 

Most recent answer

19th Jul, 2019
Jos Wielders
retired from Meander Medisch Centrum, Amersfoort, the Netherlands
Enclosed is a recent nice review about vitamin D, its actions, its measurements and the treatment of deficiencies.
1 Recommendation

Popular answers (1)

1st Sep, 2014
Constantine Kaniklidis
No Surrender Breast Cancer Foundation (NSBCF)
What is Vitamin D?: Untangling the Confusions
Although some carelessly worded studies and official nutrition committee reports in both the US and Europe casually claim that Vitamin D is more of a hormone than a nutrient, this is in error and regrettably an all too common misconception, and stems from failure to differentiate the nature and function of various Vitamin D-related compounds like ergocalciferol, cholecalciferol, 1,25-dihydroxyvitamin D, 25-hydroxy-VitaminD, and the shorthand terms calcitriol and calcidiol (distinguished below).
The preeminent Vitamin D researcher and expert Ronald Vieth, one of the "fathers" of modern Vitamin D theory, at the University of Toronto, critically shed light on these issues in his now landmark paper "Why "Vitamin D" is Not a Hormone"1, and I have extended and adopted his distinctions below for the sake of accessibility and clarity. However definite his analysis is, I will nonetheless before closing this discussion introduce one non-trivial point of disagreement that I think deserves mention as a compromise perspective that more fully and clinically realistically captures the current sense of Vitamin D..
The Facts
First we have Vitamin D which is referent to either Vitamin D3 (cholecalciferol) or Vitamin D2 (ergocalciferol). Vitamin D is the structural raw material that one or more hormones or prehormones (not prohormones) are made from, and meets the strict definition of a vitamin, namely an organic substance present in minute amounts in the natural diet (foodstuffs, not supplements) that is essential to normal metabolism, and insufficient amounts of which in the diet may cause deficiency diseases. Vitamin D itself (whether D3 or D2) is not a hormone which is strictly defined as a substance formed in one organ but transported in the blood to another organ and capable of altering the functional activity of that target organ1. In addition, the set of compounds derived from the cholecalciferol (Vitamin D3) molecule are known as secosteroids.
The Vitamin D process involves roughly that:
(1) the liver readily hydroxylates vitamin D – using cytochrome P450 enzymes –in to 25(OH)D, the primary circulating form of vitamin D,
(2) then the kidney further hydroxylates 25(OH)D into the active form 1,25-dihydroxyvitamin D which is also referred to as 1,25(OH)2D, which then acts to maintain serum calcium through sequential direct effects on calcium absorption and excretion, and through a complex series of inter-relationships with serum phosphate and parathyroid hormone.
But there are two hormonally-active substances, known as (fat-soluble) secosteroids, derived - and distinct - from Vitamin D (either D2 or D3), these being:
(1) 1,25-dihydroxyvitamin D (calcitriol) which is a calcium-regulating hormone, an adaptive hormone produced in response to calcium deficiency, it functions the same way as other steroid hormones, namely by interacting with its cognate vitamin D receptor (VDR);
(2) 25-hydroxy-VitaminD which is a prehormone (not a prohormone), a glandular secretory product, having minimal or no inherent biologic potency, that is converted peripherally to an active hormone.
However, 1,25-dihydroxyvitamin D (calcitriol) which is the metabolic product of vitamin D, is itself a potent, pleiotropic repair and maintenance secosteroid hormone acting as a a molecular switch targeting over two hundred known human genes across a wide variety of tissues2, and functions as an adaptive hormone (being produced in response to calcium deficiency).
The actions of 1,25-dihydroxyvitamin D (calcitriol) are mediated by the Vitamin D receptor (VDR), a ligand-activated transcription factor that functions to control gene expression, 1,25-dihydroxyvitamin D (calcitriol) thus serving as a transcriptional regulator of various genes2. Indeed, recent data shows that 1,25-dihydroxyvitamin D (aka, 1,25(OH)2D)-activated VDR modulates the expression of genes at both single gene loci and also at the level of gene networks3,4,5.
Given, as I have demonstrated above, that:
(1) Vitamin D is a vitamin, with
(2) 25-hydroxy-VitaminD being a prehormone (a glandular secretory product converted peripherally to an active hormone, namely 1,25-dihydroxyvitamin D (calcitriol); while
(3) 1,25-dihydroxyvitamin D (calcitriol) is a secosteroid hormone functioning as a a molecular switch which is known to target over two hundred known human genes, and thus serves as a transcriptional gene regulator,
then I would argue that we need to construe Vitamin D itself as something more than a vitamin but less than a strict hormone (that function being reserved for 1,25-dihydroxyvitamin D (calcitriol)), in order to reflect and accommodate its gene transcriptional regulator functions, and so it would be more clarifying to speak of Vitamin D as not a simple vitamin, but rather as a biomodulator vitamin, a vitamin which exerts transcriptional regulation of genes at the molecular pathway level.
Summary
- Vitamin D itself - neither cholecalciferol (Vitamin D3) nor ergocalciferol (Vitamin D2) - is not a hormone, but rather a biomodulator vitamin (capable of gene regulation);
- the primary active form 1,25-dihydroxyvitamin D (calcitriol) is a calcium-regulating hormone;
- the primary circulating non-active form 25-hydroxy-VitaminD is a prehormone, converted peripherally to the active hormone 1,25-dihydroxyvitamin D (calcitriol).
References
  1. Vieth R. Why "Vitamin D" is not a hormone, and not a synonym for 1,25-dihydroxy-vitamin D, its analogs or deltanoids. J Steroid Biochem Mol Biol 2004; 89-90(1-5):571-3.
  2. Cannell JJ, Hollis BW, Zasloff M, Heaney RP. Diagnosis and treatment of vitamin D deficiency. Expert Opin Pharmacother 2008; 9(1):107-18.
  3. Pike JW, Meyer MB. The vitamin D receptor: new paradigms for the regulation of gene expression by 1,25-dihydroxyvitamin D(3). Endocrinol Metab Clin North Am 2010; 39(2):255-69.
  4. Pike JW, Meyer MB, Martowicz ML, et al. Emerging regulatory paradigms for control of gene expression by 1,25-dihydroxyvitamin D3. J Steroid Biochem Mol Biol 2010; 121(1-2):130-5.
  5. Sutton AL, MacDonald PN. Vitamin D: more than a "bone-a-fide" hormone. Mol Endocrinol 2003; 17(5):777-91.
12 Recommendations

All Answers (16)

30th Aug, 2014
Hashem Adnan Kilani
University of Jordan
It is a vitamin that can be manufactured when the  sunlight stimulate the skin. On the other hand, can be utilized from food and can be added as supplements. 
2 Recommendations
30th Aug, 2014
Vincent Bloks
University of Groningen
Nice paper,dealing with this subject
1 Recommendation
30th Aug, 2014
Jamshid Farahati
Bethesda, Duisburg, Germany
thanks Vincent for the nice paper.
so, u prefer to state it as Hormone D?
1st Sep, 2014
Constantine Kaniklidis
No Surrender Breast Cancer Foundation (NSBCF)
What is Vitamin D?: Untangling the Confusions
Although some carelessly worded studies and official nutrition committee reports in both the US and Europe casually claim that Vitamin D is more of a hormone than a nutrient, this is in error and regrettably an all too common misconception, and stems from failure to differentiate the nature and function of various Vitamin D-related compounds like ergocalciferol, cholecalciferol, 1,25-dihydroxyvitamin D, 25-hydroxy-VitaminD, and the shorthand terms calcitriol and calcidiol (distinguished below).
The preeminent Vitamin D researcher and expert Ronald Vieth, one of the "fathers" of modern Vitamin D theory, at the University of Toronto, critically shed light on these issues in his now landmark paper "Why "Vitamin D" is Not a Hormone"1, and I have extended and adopted his distinctions below for the sake of accessibility and clarity. However definite his analysis is, I will nonetheless before closing this discussion introduce one non-trivial point of disagreement that I think deserves mention as a compromise perspective that more fully and clinically realistically captures the current sense of Vitamin D..
The Facts
First we have Vitamin D which is referent to either Vitamin D3 (cholecalciferol) or Vitamin D2 (ergocalciferol). Vitamin D is the structural raw material that one or more hormones or prehormones (not prohormones) are made from, and meets the strict definition of a vitamin, namely an organic substance present in minute amounts in the natural diet (foodstuffs, not supplements) that is essential to normal metabolism, and insufficient amounts of which in the diet may cause deficiency diseases. Vitamin D itself (whether D3 or D2) is not a hormone which is strictly defined as a substance formed in one organ but transported in the blood to another organ and capable of altering the functional activity of that target organ1. In addition, the set of compounds derived from the cholecalciferol (Vitamin D3) molecule are known as secosteroids.
The Vitamin D process involves roughly that:
(1) the liver readily hydroxylates vitamin D – using cytochrome P450 enzymes –in to 25(OH)D, the primary circulating form of vitamin D,
(2) then the kidney further hydroxylates 25(OH)D into the active form 1,25-dihydroxyvitamin D which is also referred to as 1,25(OH)2D, which then acts to maintain serum calcium through sequential direct effects on calcium absorption and excretion, and through a complex series of inter-relationships with serum phosphate and parathyroid hormone.
But there are two hormonally-active substances, known as (fat-soluble) secosteroids, derived - and distinct - from Vitamin D (either D2 or D3), these being:
(1) 1,25-dihydroxyvitamin D (calcitriol) which is a calcium-regulating hormone, an adaptive hormone produced in response to calcium deficiency, it functions the same way as other steroid hormones, namely by interacting with its cognate vitamin D receptor (VDR);
(2) 25-hydroxy-VitaminD which is a prehormone (not a prohormone), a glandular secretory product, having minimal or no inherent biologic potency, that is converted peripherally to an active hormone.
However, 1,25-dihydroxyvitamin D (calcitriol) which is the metabolic product of vitamin D, is itself a potent, pleiotropic repair and maintenance secosteroid hormone acting as a a molecular switch targeting over two hundred known human genes across a wide variety of tissues2, and functions as an adaptive hormone (being produced in response to calcium deficiency).
The actions of 1,25-dihydroxyvitamin D (calcitriol) are mediated by the Vitamin D receptor (VDR), a ligand-activated transcription factor that functions to control gene expression, 1,25-dihydroxyvitamin D (calcitriol) thus serving as a transcriptional regulator of various genes2. Indeed, recent data shows that 1,25-dihydroxyvitamin D (aka, 1,25(OH)2D)-activated VDR modulates the expression of genes at both single gene loci and also at the level of gene networks3,4,5.
Given, as I have demonstrated above, that:
(1) Vitamin D is a vitamin, with
(2) 25-hydroxy-VitaminD being a prehormone (a glandular secretory product converted peripherally to an active hormone, namely 1,25-dihydroxyvitamin D (calcitriol); while
(3) 1,25-dihydroxyvitamin D (calcitriol) is a secosteroid hormone functioning as a a molecular switch which is known to target over two hundred known human genes, and thus serves as a transcriptional gene regulator,
then I would argue that we need to construe Vitamin D itself as something more than a vitamin but less than a strict hormone (that function being reserved for 1,25-dihydroxyvitamin D (calcitriol)), in order to reflect and accommodate its gene transcriptional regulator functions, and so it would be more clarifying to speak of Vitamin D as not a simple vitamin, but rather as a biomodulator vitamin, a vitamin which exerts transcriptional regulation of genes at the molecular pathway level.
Summary
- Vitamin D itself - neither cholecalciferol (Vitamin D3) nor ergocalciferol (Vitamin D2) - is not a hormone, but rather a biomodulator vitamin (capable of gene regulation);
- the primary active form 1,25-dihydroxyvitamin D (calcitriol) is a calcium-regulating hormone;
- the primary circulating non-active form 25-hydroxy-VitaminD is a prehormone, converted peripherally to the active hormone 1,25-dihydroxyvitamin D (calcitriol).
References
  1. Vieth R. Why "Vitamin D" is not a hormone, and not a synonym for 1,25-dihydroxy-vitamin D, its analogs or deltanoids. J Steroid Biochem Mol Biol 2004; 89-90(1-5):571-3.
  2. Cannell JJ, Hollis BW, Zasloff M, Heaney RP. Diagnosis and treatment of vitamin D deficiency. Expert Opin Pharmacother 2008; 9(1):107-18.
  3. Pike JW, Meyer MB. The vitamin D receptor: new paradigms for the regulation of gene expression by 1,25-dihydroxyvitamin D(3). Endocrinol Metab Clin North Am 2010; 39(2):255-69.
  4. Pike JW, Meyer MB, Martowicz ML, et al. Emerging regulatory paradigms for control of gene expression by 1,25-dihydroxyvitamin D3. J Steroid Biochem Mol Biol 2010; 121(1-2):130-5.
  5. Sutton AL, MacDonald PN. Vitamin D: more than a "bone-a-fide" hormone. Mol Endocrinol 2003; 17(5):777-91.
12 Recommendations
1st Sep, 2014
Hashem Adnan Kilani
University of Jordan
Dear Constantine
Thank you for your clarification
15th Jan, 2016
Maurizio Liverani
Bioforce Italia
Very clear and helpful
15th Jun, 2018
Eunice Toko
Maseno University
Much appreciation to the father of mordern vitamin D, Ronald Vieth. Constantine Kaniklidis you have driven the point home. Vitamin D is a micronutriet and homones are components derived from it.
1 Recommendation
15th Oct, 2018
Béatrice Marianne Ewalds-Kvist
Stockholm University University of Turku Finland
Vitamin D system comprises hormone precursors, active metabolites, carriers, enzymes, and receptors involved in genomic and non-genomic effects.
6th Feb, 2019
Karen A. Darbinyan
Scientific and Production Center Armbiotechnology
If we look in chemical structure Vit D dose not have amin group. So trivial name used long time but finally Vitamin D is a hormone the kidneys produce that controls blood calcium concentration and impacts the immune system. It is also known as calcitriol, ergocalciferol, calcidiol and cholecalciferol. Of those, calcidiol is the form doctors most commonly focus on when measuring vitamin D levels in the blood.
2 Recommendations
24th Mar, 2019
Jos Wielders
retired from Meander Medisch Centrum, Amersfoort, the Netherlands
The original answer of Constantine Kaniklidis was very good. No further answer needed.
16th May, 2019
Jos Wielders
retired from Meander Medisch Centrum, Amersfoort, the Netherlands
Just for short
Vitamin D is not a hormone, it is even not a vitamin since we can produce it in our skin when sun-exposed. It becomes a vitamin if we are not enough sun-exposed and need to supplement it.
Then as Kaniklidis explained: 25-OH vitamin D could be consodered as a prohormnone. After the next hydroxylation it becomes 1,25 vitamin D and behaves as a true hormone
2 Recommendations
19th Jul, 2019
Jos Wielders
retired from Meander Medisch Centrum, Amersfoort, the Netherlands
Enclosed is a recent nice review about vitamin D, its actions, its measurements and the treatment of deficiencies.
1 Recommendation

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