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Vitamin D isn’t technically a vitamin in the strict sense, because unlike the other vitamins the human body can produce it itself (by exposure to sunlight).

by layer8 1y ago

slow_typist 1y ago
Dogs can synthesise vitamin C…
- delecti 1y ago
  And humans aren't dogs.
  - wongarsu 1y ago
    Most definitions of the word vitamin are not specific to humans. Wikipedia talks about "organisms", Britannica about "higher animal life", Webster about "most animals and some plants"
    - lxgr 1y ago
      What is and isn't a vitamin by definition varies from species to species.
- Aldipower 1y ago
  Wow, that is interesting. They can synthesise it in their liver?
  - bluGill 1y ago
    Many animals can. There are a gene for it, humans don't have it. There is a lot of speculation as to why, but nothing really stands out (possibly just random chance - if you eat enough there is no advantage to keeping the gene and in turn no loss from losing it. However I'm unable to rule out other possibilities) https://pmc.ncbi.nlm.nih.gov/articles/PMC3145266/ https://pmc.ncbi.nlm.nih.gov/articles/PMC3145266/ is a really interesting survey of the issue across many different species.
    - marbro 1y ago
      [dead]
    - schuyler2d 1y ago
      From the article: > Another argument supporting the suggestion that species which have lost their GLO gene were under no selective pressure to keep it, is that all species which have lost their GLO gene have very different diets but all of them have diets rich in vitamin C What would a diet poor in vitamin C be considering that "everything else" makes it? I guess root vegetables? It feels like, if anything, this would imply a GLO gene decay more often than has happened, no?
      - bluGill 1y ago
        That is probably a question for a nutritionist not me. My understanding is Grains, root vegetables, and meat are all low in vitamin C. Likely other things as well. But I'm not a nutritionist (I've read enough that I think I'm right here, but not enough to state it with confidence), so take the above with plenty of salt.
- lxgr 1y ago
  Sure, many things are vitamins for one species but not another. (In fact, every vitamin must be able to be produced by at least one species – where else would it come from?)
rhdunn 1y ago
The body can also synthesize vitamin A from beta-carotene which is effectively two vitamin A molecules joined together (one rotated 180deg relative to the other).

Vitamin D isn’t technically a vitamin in the strict sense, because unlike the other vitamins the human body can produce it itself (by exposure to sunlight).

by layer8 1y ago

Vitamin D isn’t technically a vitamin in the strict sense, because unlike the other vitamins the human body can produce it itself (by exposure to sunlight).

slow_typist 1y ago

Dogs can synthesise vitamin C…

delecti 1y ago
And humans aren't dogs.
- wongarsu 1y ago
  Most definitions of the word vitamin are not specific to humans. Wikipedia talks about "organisms", Britannica about "higher animal life", Webster about "most animals and some plants"
  - lxgr 1y ago
    What is and isn't a vitamin by definition varies from species to species.
Aldipower 1y ago
Wow, that is interesting. They can synthesise it in their liver?
- bluGill 1y ago
  Many animals can. There are a gene for it, humans don't have it. There is a lot of speculation as to why, but nothing really stands out (possibly just random chance - if you eat enough there is no advantage to keeping the gene and in turn no loss from losing it. However I'm unable to rule out other possibilities) https://pmc.ncbi.nlm.nih.gov/articles/PMC3145266/ https://pmc.ncbi.nlm.nih.gov/articles/PMC3145266/ is a really interesting survey of the issue across many different species.
  - marbro 1y ago
    [dead]
  - schuyler2d 1y ago
    From the article: > Another argument supporting the suggestion that species which have lost their GLO gene were under no selective pressure to keep it, is that all species which have lost their GLO gene have very different diets but all of them have diets rich in vitamin C What would a diet poor in vitamin C be considering that "everything else" makes it? I guess root vegetables? It feels like, if anything, this would imply a GLO gene decay more often than has happened, no?
    - bluGill 1y ago
      That is probably a question for a nutritionist not me. My understanding is Grains, root vegetables, and meat are all low in vitamin C. Likely other things as well. But I'm not a nutritionist (I've read enough that I think I'm right here, but not enough to state it with confidence), so take the above with plenty of salt.
lxgr 1y ago
Sure, many things are vitamins for one species but not another. (In fact, every vitamin must be able to be produced by at least one species – where else would it come from?)

rhdunn 1y ago

The body can also synthesize vitamin A from beta-carotene which is effectively two vitamin A molecules joined together (one rotated 180deg relative to the other).