Talk:Vitamin D

Preparation for nominating for GA

Reviewing all references for compliance with WP:MEDRS, old versus new editions, old and potentially replacable by more recent, duplications, etc. David notMD (talk) 09:11, 21 November 2024 (UTC)

There quite a lot of times the articles fails to WP:MEDSAY. Bon courage (talk) 09:16, 21 November 2024 (UTC)

I agree, and will attempt to address that as part of my review process. David notMD (talk) 09:38, 21 November 2024 (UTC)

The closer I look, the worse it looks (including that there were two bone health sections, now consolidated). David notMD (talk) 03:41, 22 November 2024 (UTC)

Either copying or moving sections to my Sandbox to edit there, and then return to article. Example: History. David notMD (talk) 12:05, 23 November 2024 (UTC)

Moved COVID-19 to Health effects and removed WP:MEDSAY text. Need to check for new lit on government or non-gov organizations issuing statements on D and COVID. David notMD (talk) 14:26, 23 November 2024 (UTC)

Completely rewrote Excess section and moved to after Deficiency. David notMD (talk) 14:16, 27 November 2024 (UTC)

You're doing a great job reviewing this for the GA nomination. Thanks. However do you think the section of Excess should be longer than the one on Deficiency? The magnitudes of these problems is very different. I think the current version has lost the problem of incorrect measurement/contamination as a cause.Jrfw51 (talk) 18:07, 27 November 2024 (UTC)

Jrfw51 I addressed Excess first because I thought the quality was worse that Deficiency, but D definitely needs work!!! I expect Vitamin D deficiency will provide useful content and references. David notMD (talk) 23:38, 27 November 2024 (UTC)

Working on the Evolution section and last paragraph of Lead. The entire Lead will likely need work after all the other content is revised. David notMD (talk) 13:18, 4 December 2024 (UTC)

Added paragraph to History on cod liver oil as treatment for rickets predating identification of vitamin D as the active by 100 years. David notMD (talk) 09:28, 6 December 2024 (UTC)

Addod three images and removed a global map image. David notMD (talk) 03:56, 8 December 2024 (UTC)

Jrfw51 Almost ready to replace the Deficiency section, with some references removed and others added. David notMD (talk) 06:28, 17 December 2024 (UTC)

Replaced Deficiency and Fortification sections David notMD (talk) 19:58, 20 December 2024 (UTC)

Added Infant deficiency subsection. David notMD (talk) 20:27, 28 December 2024 (UTC)

Added Dark skin deficiency subsection. David notMD (talk) 17:23, 30 December 2024 (UTC)

Purging more of the pre-2000 refs and will install newer when those sections are revised.David notMD (talk) 19:43, 1 January 2025 (UTC)

Added Treatment subsection to Deficiency David notMD (talk) 12:05, 2 January 2025 (UTC)

Replaced Sources subsection. David notMD (talk) 13:54, 3 January 2025 (UTC)

Started to revise Biosynthesis. David notMD (talk) 05:24, 12 January 2025 (UTC)

Biology, Biosynthesis, Mechanism of action somewhat overhauled, but Intracellular mechanisms stll needs work. David notMD (talk) 08:34, 20 January 2025 (UTC)

Nomination timing

The GA guidelines recommend that an article content be relatively stable before the nomination. For this reason, after I have completed what I see as the changes needed prior to the nomination, I intend to wait several months to see if there are major reverts, revisions or additions by other editors. May request a peer review before the GA nomination. David notMD (talk) 20:13, 22 December 2024 (UTC)

Nominated 9 February 2025. David notMD (talk) 14:27, 9 February 2025 (UTC)

Value of the Biology section?

The Biology section has four refs unique to it (one for the figure). Does the section - with the figure - add significant benefit to the article, or can it be removed, with any useful content and refs moved to other sections? Is the figure itself useful? David notMD (talk) 16:08, 13 January 2025 (UTC)

The lede is well-organized and introduces the biology section in a way that impresses as concise and educational for the common user about how vitamin D is formed and works. Could the biology and biosynthesis sections (and its figures) be combined with the calcium figure (yes, useful) to better introduce the physiological roles for vitamin D early in the article? Zefr (talk) 16:57, 13 January 2025 (UTC)

I will consider that before submitting to GA. The major part I still intend to revise/re-reference is Mechanism of action (and somewhere cover pharmacokinetics). All contributions welcome. David notMD (talk) 19:28, 13 January 2025 (UTC)

A puzzle

For several diseases and health conditions, there are observations of vitamin D deficiency being more prevalent than in healthy populations. For a few, there is additional evidence that supplementation at the amounts tested did not improve the diseases. Is low D a risk factor for these diseases and conditions, or is it something as simple that having these diseases or conditions cause people to have less exposure to UVB from sunlight? Clearly for age, and likely for obesity, these conditions can lead to less skin sun exposure. Without supplements or food fortification, sun exposure is much more of a contributor than diet. David notMD (talk) 18:29, 17 January 2025 (UTC)

For 20+ years, Holick has made the case of increased disease risk due to vitamin D deficiency. A 2019 update here and one from 2023 (unfortunately in an MDPI journal, likely predatory). But is there a WP:MEDASSESS review or clinical guideline to support it? Zefr (talk) 23:19, 17 January 2025 (UTC)

There are literally thousands of nuclear receptors for vitamin D, and therefore thousands of genes either being turned on or off. All this makes vitamin D the Swiss Army Knife of vitamins. Clearly, calcium metabolism is directly affected in ways that have clinical consequences, and I am of the opinion that any involvement of immune and autoimmune conditions is also probably directly related to vitamin D actions. The question remains in my mind as to whether non-calcium, non-immune disease observations are linked to vitamin D deficiency due to direct action, or do these myriad disease states have the indirect commonality of causing less exposure to sunlight, i.e., Occam's Razor. The true test would be whether vitamin D supplementation reverses the diseases. David notMD (talk) 14:37, 18 January 2025 (UTC)

Slight clarification. There is one and only one vitamin D receptor, but this single receptor binds to thousands of response elements, and hence regulates the expression of thousands of genes. Here are two WP:MEDASSESS sources that support that vitamin D deficiency results in increased disease risk:

• Demay MB, Pittas AG, Bikle DD, Diab DL, Kiely ME, Lazaretti-Castro M, Lips P, Mitchell DM, Murad MH, Powers S, Rao SD, Scragg R, Tayek JA, Valent AM, Walsh JM, McCartney CR (July 2024). "Vitamin D for the Prevention of Disease: An Endocrine Society Clinical Practice Guideline". The Journal of Clinical Endocrinology and Metabolism. 109 (8): 1907–1947. doi:10.1210/clinem/dgae290. PMID 38828931.
• Sizar O, Khare S, Goyal A, Givler A (July 2023). "Vitamin D Deficiency.". StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing.

Boghog (talk) 20:25, 19 January 2025 (UTC)

Although a preventive effect for vitamin D on rickets is established, the Endocrine Society guideline states that the "certainty of evidence" for prevention is low-moderate for a) preeclampsia, b) intra-uterine mortality, c) preterm birth, d) small-for-gestational-age birth, and e) neonatal mortality. Other potential effects or associations with lower disease risk remain uncertain due to the evidence that "a causal link between serum 25(OH)D concentrations and many disorders has not been clearly established." The guideline doesn't specify a dose-effect relationship that would justify using this source to say anything about prevention in the article.

The StatPearls short review doesn't give any up-to-date evidence of causality between vitamin D supplementation and disease prevention. All references under Pertinent studies are out-of-date, WP:MEDDATE.

Both reviews state that monitoring vitamin D levels in the general population is not justified, except in high-risk people. Further stated in the Endocrine Society report: "the optimal vitamin D intake and the role of testing for 25(OH)D for disease prevention remain uncertain."

This would suggest we are a long way from using vitamin D to prevent most diseases. Zefr (talk) 21:13, 19 January 2025 (UTC)

Straw man argument. No one is claiming that vitamin D prevents most diseases. That is an absurd assertion. However, there are strong associations between low vitamin D levels and certain diseases. Additionally, vitamin D plays a well-established role in regulating gene expression related to calcium uptake, metabolism, as well as the cardiovascular and immune systems. A plausible mechanism helps demonstrate that the observed association is not coincidental. Moreover, when vitamin D levels are low, supplementation is generally recommended to maintain overall health. Boghog (talk) 07:11, 20 January 2025 (UTC)

Once I am done revising section by section I intend to pause for several months before nominating for Good Article review. During that time I ask all interested editors to amend the article for completeness, gaps, contradictions, neutral point of view, references, etc. I then intend to look at everything with refreshed eyes and proceed. David notMD (talk) 08:28, 20 January 2025 (UTC)

Vitamin D and COVID-19

All of the refs need to be checked. Some are no longer active, or perhaps newer versions have been published. David notMD (talk) 14:52, 18 January 2025 (UTC)

Update completed. Most recent (2024) meta-analyses of supplement trials (large dose oral on hospital admission) concluded significant reductions in ICU admissions and mortality. David notMD (talk) 13:16, 19 January 2025 (UTC)

Nominated for Good Article

Nominating for Good Article. Everyone welcome to review/improve the article while waiting for and during review. David notMD (talk) 14:26, 9 February 2025 (UTC)

Looking at Vitamin C as a model, this article could benefit from an animal synthesis section/subsection within Evolution. It appears that most but not all amphibians, reptiles, birds and mammals have the capacity for skin synthesis, but not dogs, cats, others (?). For example, nocturnal but not diurnal fruit-consuming bats have very low serum D but maintain plasma calcium and bone mineralization. PMID 20804612 has been incorporated into the History section, as it describes lion cubs in London zoo in 1889 being vitamin D deficient and dying from a diet fed to their nursing mothers and the weaned cubs of lean horse meat, treated by changing to goat - including bones - supplemented with cod liver oil, the latter based on observations that CLO treated rickets in human children. David notMD (talk) 15:04, 9 February 2025 (UTC)

Here is an article that describes dermal synthesis of vitamin D in the North Island brown kiwi (Apteryx mantelli), tuatara (Sphenodon punctatus), and New Zealand sea lion (Phocarctos hookeri), and another article describing it in some insects. Reconrabbit 16:10, 10 February 2025 (UTC)

In my Sandbox I am drafting a subsection to cover in general amphibians, reptiles, birds, mammals and fish, plus a few exceptions that do not skin-synthesize (dogs, cats, horses, other?). I doubt that there is merit in this being species-exhaustive (!!!!), but I will look at those links. I do not intend to delve into non-vertebrates, but other editors may choose to go there. David notMD (talk) 17:09, 10 February 2025 (UTC)

Subsection added. David notMD (talk) 04:51, 11 February 2025 (UTC)

GA review

This review is transcluded from Talk:Vitamin D/GA1. The edit link for this section can be used to add comments to the review.

Nominator: David notMD (talk · contribs) 14:24, 9 February 2025 (UTC)

Reviewer: Szmenderowiecki (talk · contribs) 13:19, 7 April 2025 (UTC)

Hello there, I am going to spend the next couple of hours reviewing this article. Because this is the first time I am reviewing a topic under MEDRS, I will welcome others' input into the review. I will also refer the article for a second opinion so that the second reviewer catches stuff that I may have missed. I also think a double review is appropriate because this is a vital article and may directly concern the health of readers, who will for the large part take what's written on Wikipedia for granted.

Pinging all editors who have substantially contributed to the article or who have edited the talk page within the last 6 months : Reconrabbit, Boghog, Zefr, Bon courage

Overall progress

GA review – see WP:WIAGA for criteria

1. Is it well written?

   A. The prose is clear and concise, and the spelling and grammar are correct:

   B. It complies with the manual of style guidelines for lead sections, layout, words to watch, fiction, and list incorporation:

2. Is it verifiable with no original research, as shown by a source spot-check?

   A. It contains a list of all references (sources of information), presented in accordance with the layout style guideline:

   B. Reliable sources are cited inline. All content that could reasonably be challenged, except for plot summaries and that which summarizes cited content elsewhere in the article, must be cited no later than the end of the paragraph (or line if the content is not in prose):

   C. It contains no original research:

   D. It contains no copyright violations nor plagiarism:

3. Is it broad in its coverage?

   A. It addresses the main aspects of the topic:

   B. It stays focused on the topic without going into unnecessary detail (see summary style):

4. Is it neutral?

   It represents viewpoints fairly and without editorial bias, giving due weight to each:

5. Is it stable?

   It does not change significantly from day to day because of an ongoing edit war or content dispute:

6. Is it illustrated, if possible, by images?

   A. Images are tagged with their copyright status, and valid non-free use rationales are provided for non-free content:

   B. Images are relevant to the topic, and have suitable captions:

7. Overall:

   Pass or Fail:

Lead

• Unlike the other twelve vitamins, vitamin D is only conditionally essential - in a preindustrial society people had adequate exposure to sunlight and the vitamin was a hormone, as the primary natural source of vitamin D was the synthesis of cholecalciferol in the lower layers of the skin's epidermis, triggered by a photochemical reaction with ultraviolet B (UVB) radiation from sunlight. - IDK where to start. I'd put a source near conditionally essential. What changed since the beginning of the Industrial Revolution? Did people change so much that vitamin D stopped being a hormone? I don't think I see it anywhere and the lead doesn't say anything about it. I think you can just say how it's generated - sunlight and all that, and that because we can generate some vitamin D from UV radiation, vitamin D is not strictly essential.
• Foods such as the flesh of fatty fish are good natural sources of vitamin D; there are few other foods where it naturally appears in significant amounts - Flesh of fatty fish is among the few significant natural food sources of vitamin D
• are fortified -> add wikilink to Food fortification

Generally

• There's this book called Feldman and Pike’s Vitamin D, which appears to be a comprehensive reference on all things Vitamin D. The fifth edition from 2024 is available on the internet, but the Wikipedia Library does not carry it. I'd strongly advise you check this out.
• There's so much chaos in this article. The order of things I'd expect from a good article is this: what this is, varieties of this thing, how we make it, what it does, how it does what it does, how much of it we need, what happens if there is too much/too little of it, efforts to prevent these problems, if any; other regulations surrounding it, like "allowed health claims", and how it was discovered. Compare with e.g. Nicotinamide adenine dinucleotide (an FA), where the order is roughly the same.

Types

• Vitamin D3 was shown to result from the ultraviolet irradiation of 7-dehydrocholesterol. -> Who showed it? When? There is no source to that effect.

Biosynthesis

• Move up biosynthesis to this section.
• You describe D3 synthesis. Is there any info on D2 synthesis? Are there organisms that can synthetise one but not the other? What's the effect of such change?

Evolution

• For at least 1.2 billion years, eukaryotes - a classification of life forms that includes single-cell species, fungi, plants, and animals, but not bacteria - have been able to synthesize 7-dehydrocholesterol. When this molecule is exposed to UVB light from the sun it absorbs the energy in the process of being converted to vitamin D. The function was to prevent DNA damage, the converted molecule being an end product without vitamin function. - this doesn't appear to be substantiated by an inline source. If it is hidden in the 2000 source, let me know, but as far as I can see from its abstract, it's not there. The other two cited sources do not confirm this passage. In general, I'd simply put citations at the end of each sentence so that we avoid the appearance of improper editorial synthesis or just sloppy citation practices.
• Ditto some species of not exactly an encyclopedic style of writing
• Only circa 500 million years ago, when animals began to leave the oceans for land, did the UV-converted molecule take on a hormone function as a promoter of calcium regulation. - this is contradicted by the 2022 source cited, which says this: Since the levels of 1,25(OH)2D3 in lamprey are similar to that in higher vertebrates, respective enzymes, such as CYP2R1 and CYP27B1, must have co-evolved with VDR [22]. Similar co-evolution also happened for the vitamin D transport protein vitamin D binding protein (encoded by the GC gene) [25]. This indicates that some 150 million years before the first species left the ocean and had the need for a stable skeleton, vitamin D endocrinology was already established. Thus, from an evolutionary perspective, the control of calcium homeostasis was rather a secondary than a primary goal for establishing the vitamin D endocrine system. The article does say that animals left the ocean, but that was 385Mya, not 500Mya.
• See Evolutionary Biology: Mysteries of Vitamin D in Fish in this book
• Wikilink amphibians, osteoclast
• The second paragraph of evolution is a copyvio from the abstract of this paper, with word-for-word copying of the last sentence which doesn't make much grammatical sense; I have no idea why the other two papers are cited here.

Animal biosynthesis and food sources

• Carnivores and omnivores also get the vitamins from their diets, and herbivores can get some vitamins from fungi that are consumed along with plant foods. I'd like you to expand a bit on this source; however, the source cited to this sentence does not even contain the word "fungi", "mushrooms" or similar.
• In captivity, artificial lighting that provides UVB light is preferred to fortified food -> the only passage that somewhat approaches what is said here is this Dietary sources of vitamin D may not be sufficient to prevent rickets and osteomalacia. Diets with as much as 3,000 IU vitamin D3/kg did not prevent bone fractures and cortical thinning in green iguanas. Bulbs emitting UVB placed over the lizards at ~12–18 in. for 12 hours/day appeared to reverse the signs in the least severely affected lizards. That's not a recommendation. I can't read it from there. The same applies to the following sentence. I can't see this recommendation in birds, which basically says "give supplements or a UV-B source" or in amphibians, where point 6 of the cited paper just says that it's hard to breed amphibians in captivity, which could be due to vitamin D deficiency.
• Unlike land-based vertebrates, large amounts of vitamin D3 are stored in the liver -> Unlike land-based vertebrates, fish store large amounts of vitamin D3...}}
• How much of vitamin D is being produced annually? In which forms is it normally produced?

Biology

• This section appears to be duplicating the Mechanism of action section. I'd like to understand why. Maybe move up the mechanism of action section to this place.

Mechanism of action

• Calcitriol exerts its effects primarily by binding -> Calcitriol, the biologically active form of vitamin D, exerts...
• In the absence of calcitriol, the VDR is mainly located in the cytoplasm of cells. - No source for this statement, ref 207 does not say this. While I know that everything is either inside the nucleus or in the cytoplasm, it could be for example that it is attached to some sort of organelle while it is inactivated (not how it works, but you need to write for the layman who doesn't have a background in biochemistry or cell biology.
• active vitamin D - no full stop after D
• These include TNFSF11 (RANKL), crucial for bone metabolism; SPP1 (Osteopontin), which is important for bone metabolism - weird formulation in this sentence

Metabolism

• The regulation section should be generally incorporated into this section. It may be that you should rename it, but the whole point is, this replies to the "what does it do" and "how does it do what it does" part. You could even put it before the mechanism of action section, as it is now.
• Ref 206 could be updated to the version from 2024. Check if it still says the same thing; maybe add some info that could be new.
• This hydroxylation also leads to a greater degree of inactivation: the activity of calcitriol decreases to 60% of original after 24-hydroxylation, whereas ercalcitriol undergoes a 10-fold decrease in activity on conversion to ercalcitetrol. - source?