3 ms·

It's both isn't? In pill form it's a vitamin... from the sun it's a hormone

ashtonkem 6y ago
Same compound. The definition of vitamin includes the inability of the organism to synthesize it itself, so vitamin D can’t be an actual vitamin
- ska 6y ago
  I suspect that is an idiosyncratic definition.
  - ashtonkem 6y ago
    “A vitamin is an organic molecule (or related set of molecules) that is an essential micronutrient which an organism needs in small quantities for the proper functioning of its metabolism. Essential nutrients cannot be synthesized in the organism, either at all or not in sufficient quantities, and therefore must be obtained through the diet.” https://en.wikipedia.org/wiki/Vitamin https://en.wikipedia.org/wiki/Vitamin
    - beagle3 6y ago
      By this definition you might argue that it's a vitamin north of some geographic line and a hormone south of that line .... Also, nicotinamide (one form of Vitamin B3) is a metabolite of niacin (nicotinic acid, another form of Vitamin B3). Humans can produce the former from the latter, but require at least one of them from the diet. Does that make niacin a vitamin, but nicotinamide a hormone? They are not equivalent, but as far as "being essential", they are substitutes. (No idea myself, just rumbling thoughts)
      - ashtonkem 6y ago
        I believe the capability of humans to synthesize sufficient amounts of D3 under many circumstances makes it a hormone, not whether or not I’m synthesizing it right now. It doesn’t suddenly go from being a hormone to a vitamin once I took up an office job, I just stopped doing the activities required to self-synthesize it. I think things get very tricky to define when you need at least one compound that can complete some biological process, but there are several different potential compounds that could do the job, some of which have to come from diet and others can by synthesized by the human body.
        Melting_Harps 6y ago
        > I believe the capability of humans to synthesize sufficient amounts of D3 under many circumstances makes it a hormone Its molecular structure precursor is cholesterol, a steroid hormone which by convention is a molecule with 3 hexanes attached to pentane and an R group, it under goes a series of cleaves in the presence of UV light to yield D3. D3 and its known analogue's behavioiur and bioactivety also behaves like a steroid/hormone in that it can passively diffuse across a membrane. and helps down-regulate other metabolic reactions. Its effects on reducing inflammation in IG patients is well documented and worth checking out. Here is a good review on Corticosteroids, specifically on there effects on inflammation treatment. https://www.medicinenet.com/corticosteroids_vs_nsaids/article.htm#what_are_corticosteroids_and_nsaids https://www.medicinenet.com/corticosteroids_vs_nsaids/articl...
- msclrhd 6y ago
  Then what about vitamin A? Our body can synthesize it from beta-carotene.
  - ashtonkem 6y ago
    Then it’s probably not a vitamin if we can synthesize enough of it to function fine. The definition of vitamin is that it’s gotta be organic, necessary for healthy functioning, and we must be incapable of synthesizing enough of it to survive, even if it’s also available in our food. This is why cholesterol isn’t a vitamin; it’s necessary for us to live, but we’re fully capable of synthesizing enough of it on our own.

Same compound. The definition of vitamin includes the inability of the organism to synthesize it itself, so vitamin D can’t be an actual vitamin

ska 6y ago
I suspect that is an idiosyncratic definition.
- ashtonkem 6y ago
  “A vitamin is an organic molecule (or related set of molecules) that is an essential micronutrient which an organism needs in small quantities for the proper functioning of its metabolism. Essential nutrients cannot be synthesized in the organism, either at all or not in sufficient quantities, and therefore must be obtained through the diet.” https://en.wikipedia.org/wiki/Vitamin https://en.wikipedia.org/wiki/Vitamin
  - beagle3 6y ago
    By this definition you might argue that it's a vitamin north of some geographic line and a hormone south of that line .... Also, nicotinamide (one form of Vitamin B3) is a metabolite of niacin (nicotinic acid, another form of Vitamin B3). Humans can produce the former from the latter, but require at least one of them from the diet. Does that make niacin a vitamin, but nicotinamide a hormone? They are not equivalent, but as far as "being essential", they are substitutes. (No idea myself, just rumbling thoughts)
    - ashtonkem 6y ago
      I believe the capability of humans to synthesize sufficient amounts of D3 under many circumstances makes it a hormone, not whether or not I’m synthesizing it right now. It doesn’t suddenly go from being a hormone to a vitamin once I took up an office job, I just stopped doing the activities required to self-synthesize it. I think things get very tricky to define when you need at least one compound that can complete some biological process, but there are several different potential compounds that could do the job, some of which have to come from diet and others can by synthesized by the human body.
      - Melting_Harps 6y ago
        > I believe the capability of humans to synthesize sufficient amounts of D3 under many circumstances makes it a hormone Its molecular structure precursor is cholesterol, a steroid hormone which by convention is a molecule with 3 hexanes attached to pentane and an R group, it under goes a series of cleaves in the presence of UV light to yield D3. D3 and its known analogue's behavioiur and bioactivety also behaves like a steroid/hormone in that it can passively diffuse across a membrane. and helps down-regulate other metabolic reactions. Its effects on reducing inflammation in IG patients is well documented and worth checking out. Here is a good review on Corticosteroids, specifically on there effects on inflammation treatment. https://www.medicinenet.com/corticosteroids_vs_nsaids/article.htm#what_are_corticosteroids_and_nsaids https://www.medicinenet.com/corticosteroids_vs_nsaids/articl...
msclrhd 6y ago
Then what about vitamin A? Our body can synthesize it from beta-carotene.
- ashtonkem 6y ago
  Then it’s probably not a vitamin if we can synthesize enough of it to function fine. The definition of vitamin is that it’s gotta be organic, necessary for healthy functioning, and we must be incapable of synthesizing enough of it to survive, even if it’s also available in our food. This is why cholesterol isn’t a vitamin; it’s necessary for us to live, but we’re fully capable of synthesizing enough of it on our own.