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Not a single mention of it's use/overuse in practically every product in the cosmetics industry related to skin care... really, nothing? — Preceding unsigned comment added by (talk) 14:14, 25 November 2020 (UTC)


Vitamin A is stored in hepatic stellate cells, not in hepatocytes. — Preceding unsigned comment added by (talk) 14:17, 20 January 2015 (UTC)


Is retinol pronounced the same as retinal? Or does the latter rhyme with 'pal' while the former rhymes with 'all'? Are these two words treated as homonyms for the most part? Dexter Nextnumber (talk) 06:30, 25 June 2010 (UTC)


vitamin A is no longer measured in international units, rather, currently we use retinol equivalents to account for the lower retinol actually usable in the body from carontenoids. so 1 retinol equivalent (RE) is 1ug of retinol or 3.33 IU of vitamin A from retinyl ester sources (retinol) and 10 IU from beta-carotene sources like vegetables. i think you should change the "units of measurement" section to reflect this.

I think IU should be put back, perhaps in parenthesis after RE. Somebody wondering if they're, I don't know, taking too much cod liver oil is going to know anything about RE when all supplements use IU. I think it defeats the purpose of having easily accessible and understandable information.

Retinoid metabolism figure[edit]

my graduate advisor made a good retinoid metabolism figure for her review paper: Lane, MA and Bailey SJ. Role of retinoid signalling in the adult brain. Progress in Neurobiology, Volume 75, Issue 4, March 2005, Pages 275-293 [1]


Older post

Vitamine A so useful for polar animals and top philosophical question[edit]

1) Anybody knows why Vitamine A seems to be so useful for polar animals ? 2) about the paragraph "Danger" : "... The media and the medical establishment work together to vilify the very substances that can prevent suffering and disease ..." I must add a bit of personal reasoning for that : in these days of agressive economic rules, it seems that business promotion covers up most moral issues, so the medical establishment is logically implicated, but for the corporates medias, it seems to be a bit different, so the first goal being to survive and grow, they'll tend : a)to carefully consider the opinion of their most usefull and critical customers (other corporates doing some advertissments). b)multiply business occasions, therefore push publication numbers through a careful choice of the news to publish, ironically in that field crimes got a hight paidload, and unluckily for humanity it generate some more crime through copycat behaviour. Therefore not be too keen about vitamins could makes sense, because it could boost medical busisness and related advertising! So the conclusion is that the economic system really need to evolve some more, full liberalism does not work anywhere, especially not when commecrcial success is directly corelated with the customer distress, this is frankly crazy to let such a system evolve by itself (a bit like Dr. Jekil leading the way), last question is where does it stop ? There must be some sort of automatic regulation at work, the probable worst one is when so many people are sick that the whole system colapses, and the best one appears when a majority of people become sudently more aware on many things and take action that are really good for them, but the reallity is probably inbetween, but where ? Following entropic laws, we got a bias toward the worst, but following evolution of living organisms, we got a bias toward improvment! The solution is probably found through information and culture, please keep writing, and sorry for the topic switch (feel free to move this paragraph at the end).

More recent posts not placed under the older one[edit]

According to an article at, vitamin A overdose did not kill any explorers:

The warnings against vitamin A usually include mention of Arctic explorers who died from vitamin A overdose because they consumed polar bear livers. Actually, the early explorers did not die from eating polar bear liver. They did suffer from exfoliative dermatitis and hair loss. In 1988, a team of Swedish scientists discovered that polar bear and seal livers tend to accumulate the metal cadmium. The symptoms for cadmium poisoning are exfoliative dermatitis and hair loss, but don't expect to hear about this on the evening news. Rather, expect continuing stories about the alleged dangers of vitamins A and D. The media and the medical establishment work together to vilify the very substances that can prevent suffering and disease.

Unfortunately it contains no references. The same information is used at (defunct)

Another vitamin that Americans have been caused to become concerned about is vitamin-A. Its ridiculously low RDA is 5000 I.U.. A person eating a modest meal of carrots and liver consumes at least 100,000 I.U. of vitamin-A, and he does it without a doctor's prescription, and each spoonful is in violation of the RDA's. Spinach, sweet peas, potatoes, red peppers and dried apricots would also be disallowed from the doctor's prescription if the FDA ever is allowed to enforce the RDAs. In February 2001, UNICEF reported that a program that began in 1988 giving high-dose capsules of vitamin-A to strengthen the body's immune system has averted one million child deaths. If vitamin-A is so abundant in common food then how could the medical authorities convince the doctors to warn the public about the dangers of taking too much and that it could be poisonous ? The answer most frequently cited is that eating polar bear livers, which contain as much as 8,000,000 I.U. of vitamin-A, was fatal for the early arctic explorers. My God ! When was the last time that you ate polar bear liver ? The tragedy behind this ridiculous stance is that it is based on misinformation. To begin with, the early explorers did not die from eating the polar bear liver which was so delicious that they devoured large amounts at each meal, but rather became sick, suffering from dermatitis and defoliation. Then, ironically, in the late 1980's, a team of Swedish scientists discovered that polar bear liver adsorbs large amounts of cadmium metal found in the arctic water. The symptoms of cadmium metal poisoning are dermatitis and defoliation. Thus, the ailments of the early explorers were caused by the cadmium in the polar bear liver, and not the large amount of vitaminn-A. The tragedy is that despite the scientific evidence, "too much" vitamin-A still remains "toxic" in the doctors minds.

But again, no references.


I see no reason to lend any of this credence. —Casey J. Morris 07:39, July 22, 2005 (UTC)
What reason do you have to lend credence to the point of view they're arguing against, other than the fact that you've been preconditioned with it? -- 13:18, 18 October 2005 (UTC)
That article deliberately mixes and confuses carotenes with retinoids. They are NOT the same thing. Much of the 'vitamin A' in a carrot and liver meal is carotenes, but carotenes aren't really toxic. On the other hand there are concerns about eating a lot of liver, because it does contain significant retinoids.WolfKeeper 16:31, 30 December 2005 (UTC)

By God, the section on vitamin A overdosing is so ingrained in the traditional thinking. Shouldn't it at least present the alternate point of view? It's the synthetic form of vitamin A (included inside most supplements) which gets toxic very quickly. The only damage that the natural version of vitamin A (liver, et al) can cause is short-lived, and clears up as soon as the high dosage is withdrawn. Dr. Joseph Mercola's view on the subject: [unreliable fringe source?] "Natural Vitamin A Found in These Foods is Superior to Synthetic Form"] One of the many Weston A. Price Foundation articles on the topic: "Vitamin A: The Forgotten Bodybuilding Nutrient"

Okay, I've also added a short paragraph to express this.

The Dr. Mercola article can no longer be found. In addition, he has been cited by the FDA for making false claims before. He really should not be considered a reliable source. — Preceding unsigned comment added by Angmar09 (talkcontribs) 17:23, 30 October 2011 (UTC)


In 2003-4 about thirty children died in North East India after an overdose of Vitamin A drops, raising concerns about the programme. Will try to get references soon.
"One of the suspected causes for the deaths was the unilateral switch by UNICEF to the use of a 5 ml dispenser. The Government of India's stated norm is a 2 ml dose. The dispensing health workers were reportedly not warned of this or trained adequately. The Report, however, takes cognisance of the fact that a change in methods of dispensing in some areas might have resulted in the administration of a higher dose and that some children may have suffered side effects due to the plastic cup measuring out a mega dose."

-- 23:08, 29 December 2005 (UTC)jclements (not original commenter above)

Source for cadmium buildup in polar bear livers...[edit]

Don't know if this proves anything, just throwing it in there. -- 23:09, 29 December 2005 (UTC) jclements

"Polar bear (Ursus maritimus) livers (67) from six Management Zones in the western and central Canadian Arctic were analysed for 22 elements. Several, Ba, Be, Co, Mo, Ti, V and Zr, were near the detection limit in all cases. Baseline data were obtained for the remaining elements, Ag, As, Ca, Cd, Cu, Fe, Hg, K, Mg, Mn, Na, P, Se, Sr and Zn. No statistically significant effect of age, sex or geographical location was found for any of the elements, except Cd, Hg and Se, for which age and geographical location effects were found. The frequency distribution of Zn levels was bimodal. The second peak in the distribution appeared to be related to elevated levels of Cu. The average level of Cu was 104 mg kg-1 (dry wt.), higher than other marine mammals. Average levels of Cd were significantly higher in the eastern zones, but were always less than 1.0 mg kg-1 (dry wt.), significantly lower than their prey species. This may be due to the preference of polar bears for eating seal skin and fat which is low in Cd. Mercury levels tended to be higher in the western zones bordering the Beaufort Sea, which may be related to a higher proportion of bearded seal in their diet."

Genetically engineered rice[edit]

Due to the high prevalence of vitamin A deficiency in rice-eating societies,

I changed that to

Due to the high prevalence of vitamin A deficiency in developing countries,

because the old version suggested (probably involuntarily) that consumption of rice may lead to vitamin A deficiency. The problem is not what the people eat, but what they don't eat in sufficient quantities, of course. (E.g. green leafy vegetables, root vegetables like carrots and sweet potatoes, carotene-rich fruit, eggs, liver, green peas etc.) Of course rice was chosen because rice is a staple in many developing countries, and thus will find more acceptance than other grains.

Full retinol synthesis[edit]

Does anyone have a link to an article or a website that has full retinol synthesis scheme?

What enzyme or pathway is responsible for the cleavage of beta-cartene into retinol? —Preceding unsigned comment added by (talk) 04:38, 23 November 2010 (UTC)

growth hormone[edit]

Vitamin A affects the production of human growth hormone.

How exactly? It inhibits it? Promotes it? Does it affect its synthesis, or does it attack it once it is made? Does it affect the enzymes used to synthesis it? How? Is it a competitive inhibitor or non-competitive? Or a co-enzyme, or even a substrate? This has to be one of the most amibiguous sentences i've come across on wikipedia. Which is especially bad as it seems it may describe a rather important process. Someone fix it, and get a source too - mastodon 23:05, 1 May 2006 (UTC)

Fat-man factor-A[edit]

What's with the fat-man factor-A reference? Is that a joke, a piece of disinformation? Should it be removed?

I've removed it for now. If someone can find a reference for it, it can be added back in. --Ed (Edgar181) 12:26, 7 May 2006 (UTC)

Usage Against Acne[edit]

I read about the potential for eliminating acne in a very small, local magazine (which has since been thrown out), and it said that dietary supplements, ie daily vitamin tabs, could also fight acne, not just the topical ones. So I started taking a Vitamin A and D mixture I got at the grocery store, and sure enough, it works. Someone might want to emphasize that it is not necessarily just topical.

I wish I had that article..... (it cited a "recent" research study in the area. I don't know what "recent" means in terms of medicine)

You probably don't want to mess with that. Retinyl parmitate (and isotretinoin) are both fairly toxic in the doses needed to deal with acne and require medical checks and advice to undertake safely.WolfKeeper 20:58, 10 July 2006 (UTC)
Is this also true of topical application of retinol on the skin? Is it dangerous to the skin, or does it get passed further into the system if it is applied topically? What about people who have acne in and around the ears, or just inside the edge of the nose, or on the eyelids, shoulders, scalp, armpits, and the pits of the elbows? In the United States, is retinol a controlled substance, and subject to seizure by Federal authorities? If it is dangerous, how dangerous? Are there any studies that can be cited in the main page of this article? Dexter Nextnumber (talk) 09:49, 23 June 2010 (UTC)

Vitamin A redirects here; should it?[edit]

As I understand it, the term "vitamin A" refers not just to retinol, but to any nutrient that permits its synthesis or the synthesis of bioequivalent substances (carotenoids, for example). Maybe there should be a quasi-disambiguation page at Vitamin A, rather than a redirect to this article? --Trovatore 17:55, 17 October 2006 (UTC)

I went ahead and made the disambig page. An accuracy check would be welcome (this is not my field). --Trovatore 06:18, 4 November 2006 (UTC)
No, vitamine A is beta carotene from plants. Retinol is a product of its enzymatic processing in animals. They are different things. Should not merge. Biophys 04:42, 5 February 2007 (UTC)
Well, come on, there's no question that retinol counts as vitamin A. The question is whether carotenoids are also vitamin A; that is, whether vitamin A is a more general term than any one chemical. I think it is. Retinol is a chemical; vitamin A is any one of several chemicals. --Trovatore 06:13, 5 February 2007 (UTC)

No one has responded to me directly on the question of whether my formulation is accurate, but neither has there been any apparent objection to my changes. I was really hoping to get some expert comment.

Anyway, if I'm correct that "retinol" is a specific molecule whereas "vitamin A" is a group of substances having a similar biochemical role, then it occurs to me that most of the info in this article should be at vitamin A. What the "sources" have in common, for example, is not being sources of retinol, but being sources of vitamin A. And it's not possible to have a diet specifically deficient in retinol, because you don't need any, provided you get vitamin A in other forms.

So my revised proposal is that most of the content of this article should move to vitamin A; then a small retinol article should also exist, with the chemical properties specific to retinol, and any biological information that doesn't apply to other forms of vitamin A. Probably the cleanest approach is to delete the dab page currently at vitamin A, move retinol there (to preserve the edit history), and then split out the retinol-specific information to a new retinol article.

Comments? --Trovatore 07:53, 20 December 2006 (UTC)

I agree with everything you said. Dekimasu 09:12, 31 December 2006 (UTC)
I also agree with the changes you propose. --Coppertwig 03:24, 1 January 2007 (UTC)
Why don't you start doing that?--Alnokta 11:51, 9 January 2007 (UTC)
Please note that in line with medical drug articles being named as per International Nonproprietary Name, I have merged All-trans retinoic acid and the clinical usage parts of retinoic acid to Tretinoin. Retinoic acid also discussed its role in embryological development, and this I have moved to expan retinol's coverage of Vitamin A's normal endogenous roles & functions. With Retinoic acid thus covering a endogenous substance having various roles and also a specific drug, I have left this as a disambiguation page. David Ruben Talk 02:44, 14 January 2007 (UTC)
Hm, I'm not quite sure I follow the rationale there. Shouldn't the retinoic acid page be about the specific chemical substance, just as retinol should be, with the common physiological information moved to vitamin A? --Trovatore 06:28, 14 January 2007 (UTC)
I would agree that the common physiological information should in due course be moved to vitamin A. What I tried to achieve was the initial process of collecting the normal physiological actions of the group in the one place and, for now, the retinol article was far more extensive than the vitamin A. Similarly the clinical drug information needed to be under the standard international medicinal term (International Nonproprietary Name) of Tretinoin.
The retinol/vitamin A merger was a separate proposal (as agreed above, but yet to be enacted). I'm not sure that physiologically there is any (real) difference (that is known) between retinol & its acid retinoic acid, and I agree description of function under the collective term of Vitamin A is more appropriate. I can forsee then that there will be almost no (or at least no more than a very short article) specific information to state about retinol, and retinoic acid will likewise remain very short and in large part point to both Vitamin A (rather than current pionting to retinol) for the physiological information and tretinoin for the clinical information.
I am happy to do this next stage, but it seemed from the discussion above that Trovatore, Coppertwig or Alnokta might be in the process of doing this themselves, and there was no point my jumping in and duplicate a task that might be in progress by others.... David Ruben Talk 08:54, 14 January 2007 (UTC)
I was hoping to get someone with more expert knowledge than I to do the actual content moves. My point about "retinoic acid" is that it still deserves a (short) article about its chemical properties. Yes, the physiological stuff probably belongs at vitamin A. --Trovatore 18:49, 14 January 2007 (UTC)
In other words, please go ahead and do the next stage, Mr. Ruben. (^^) Dekimasu 14:28, 16 January 2007 (UTC)
I've (hopefully) fixed most of the interwikis, anything that is called the equivalent of "Vitamin A" now interwikis to Vitamin A whereas articles called Retinol still link to this article. Hopefully that will reduce bot overwrites. I couldn't fix languages that don't use Latin or Cyrillic alphabets, as those are the only alphabets I can read. People might be interested that Vit A was about twice as popular a name as Retinol, though the German WP uses Retinol. Also, as far as I saw, other languages only have one article on this topic. Someone took the Merge notice of this page, presumably because nothing has happened - but the merge notice is still on the Vitamin A page. I don't have an opinion on the merge. Walkerma 06:32, 6 February 2007 (UTC)
There was an apparent consensus for the merge (it won't result in a redirect, I believe), although I have had some trouble contacting David Ruben, who seemed most qualified to make the move. Dekimasuが... 12:22, 6 February 2007 (UTC)
As I read the discussion, the consensus is not exactly for merging, but for refactoring -- roughly speaking, the chemical information to stay at retinol, and the physiological information to move to vitamin A (though retinol-specific physiological information might at least be repeated at retinol). --Trovatore 22:33, 6 February 2007 (UTC)
Yes, that's what I meant as far as not resulting in a redirect. The main result is that Vitamin A will have some actual content. I suppose that someone else can perform the move, but David seemed to have the most technical knowledge. Since you initiated the discussion, are you interested in doing it? Or I'll do it myself, but I'm not sure what should be moved over besides the sections on nutrition and genetically engineered rice. Dekimasuが... 03:20, 8 February 2007 (UTC)

Please keep these unmergered as yes Retinol is from Vitamin A as much as Plastic is from Petroleum or Bread is from Flour. All these items are worthy of their own articles. Fellow Wikies, please stop being so "Delete Happy" and "Merge Manic". Wikipedia is a paperless format that can store information ad naseum. One persons "unneeded article" for deletion is another Wiki's hard work. —Preceding unsigned comment added by (talkcontribs)

The proposal is not really to merge, but to redistribute information. You say that retinol and Vitamin A are very different, but now all of the information on Vitamin A is shown on the retinol page. That's the issue we are discussing here. Dekimasuよ! 12:09, 4 March 2007 (UTC)

Synthetic Sources[edit]

I added a list of synthetic source trade names. They are all available from the FDA's lists of approved drugs; however I got the original list from Lists are not subject to copyright in the U.S. under Feist Publications, Inc. v. Rural Telephone Service Co., 499 U.S. 340

--Selket 06:05, 21 January 2007 (UTC)

Reference number 6[edit]

I followed the link to the reference "Stone, Brad. Vitamin A and Birth Defects, 6 October 1995, retrieved 20 June 2007" and discovered that this does not appear to be the high-quality sort of source that you would expect to be used in an encyclopedia. It bases its information on "the forthcoming New England Journal of Medicine article" but does not even say what article this is. I believe this is the same famous 1995 piece by Rothman, et. al. on which nearly every subsequent warning about retinol has been based. In my understanding, the conclusions of the Rothman piece do not support the recommendations made in reference 6, and especially not the extreme statement made here that references 6:

Even twice the daily recommended amount can cause severe birth defects.[6]

This erroneous statement needs to be changed, and whatever replaces it needs to be based on a careful reading of the Rothman NEJM 1995 article. Neoprote (talk) 10:45, 29 May 2008 (UTC)

about CAS No.[edit]

It is confused me that i find 2 kind of CAS No.11103-57-4 and 68-26-8 of which the structures are same.And what confuse me more is that it is different between the english vision and chinese vision of the same article. And i can only seach CAS No. of 68-26-8 in sigma-aldrich.i donot know which one is the corrected one. (talk) 15:45, 17 November 2008 (UTC)Cheney

Animal Form?[edit]

The article states that Retinol is the "animal form of vitamin A" is this correct? I do not understand animal form, is it supposed to say "Acid form" instead? DiscoElf (talk) 14:38, 19 October 2009 (UTC)

No, it's supposed to say "animal form", as opposed to vitamin A from plant sources, which are carotenoids. Whether this phrase is a good way of expressing that is another question, of course. Do you have an alternative suggestion? --Trovatore (talk) 20:56, 19 October 2009 (UTC)

Much material should be moved to vitamin A[edit]

I hadn't looked at this article for a while, and it appears to me that a great deal of material is creeping in that would be better handled at vitamin A. The whole reason for having two separate articles is that vitamin A comprises quite a few different molecules (arguably including carotenoids, which are referred to as pro-vitamin A by some sources, but just vitamin A by others). On the other hand, retinol is one specific chemical.

So I think the retinol article should be primarily about retinol's chemical properties. If there are physiologic properties specific to retinol, as opposed to other forms of vitamin A, then I suppose those are also reasonable to treat here. But material about the physiological effects of vitamin A in general, as opposed to retinol specifically, should be moved to vitamin A. --Trovatore (talk) 23:45, 11 December 2009 (UTC)

I just came here to make the exact same comment. Glad you agree! I'll move some stuff about vitamin A vitamers other than retinol to the vitamin A article, leaving one-line summaries and main article redirects behind. SBHarris 23:48, 21 July 2010 (UTC)

Controlled substance?[edit]

Does anyone know if the United States treats retinol as a controlled substance to be made available only to those who have a prescription? Whatever the thrust of the main page of this article, there should be an easy way for ordinary people to look up the chemical's availability, especially as it is available for purchase online, or through the "web". Dexter Nextnumber (talk) 17:22, 23 June 2010 (UTC)

I don't think it's controlled. Products containing it are readily available here over-the-counter. Dmarquard (talk)

Retinol skin treatments[edit]

I'm seeing retinol and or retinoids being mentioned all over the internet as an 'anti-ageing' skin treatment yet not a single mention of retinol being used for skin treatment either topically or as a supplement on the wikipedia page... Seems to be worth a section by someone knowledgeable on the topic to either support or debunk this usage. — Preceding unsigned comment added by (talk) 10:56, 6 February 2018 (UTC)

I agree. I don't know where that section belongs, but there are citations to support it (e.g., [[2]]). Dmarquard (talk)
In the interest of public health I think this section is very important to add, even in a limited form. I tried to draft a paragraph a year ago but the references were considered too weak. Is there any reason not to use the above reference suggestion with a "there is limited evidence..." type of paragraph? Mentor Talk Contributions 14:42, 13 July 2020 (UTC)
Medical content should be supported by WP:MEDRS reviews, which mainly are absent from the literature. This study mentioned above is a small study on just 30 subjects, so is unuseable primary research. PMID 26969582 is a 2016 review showing efficacy of retinoids for photodamaged skin; it references PMID 20633013 as an earlier review on this topic, but otherwise there isn't much review literature to support further discussion about skin treatments. Zefr (talk) 15:53, 13 July 2020 (UTC)
I think the point is that the majority of humans that encounter the word 'retinol' will do so by being marketed skin products to. Having no reference at all to it on it's wikipedia page leads people to blogs and youtube videos that often spout nonsense. I would contend that the use in consumer products does not count as a medical application and should thus not be subject to WP:MEDRS. I strongly believe the public would benefit from even a marginal reference that states "Retinol is used in skin care products often marketed towards anti-ageing. There is currently no evidence to support it as a medical treatment". Mentor Talk Contributions 08:18, 14 July 2020 (UTC)
'Antiaging' is a medical effect. The content you wish to add - "no evidence to support it as a medical treatment" - is appropriate if supported by a reputable source. There is this page from the Mayo Clinic which may be useful, as it mentions retinol and other ingredients common in cosmetics products, and provides an FDA statement: "Food and Drug Administration (FDA) classifies creams and lotions as cosmetics, which are defined as having no medical value". Zefr (talk) 16:06, 14 July 2020 (UTC)
I believe 'ageing' is not yet a medical indication. And as you indicate yourself cosmetic has "no medical value" and should in my opinion thus not be subject to WP:MEDRS. Would you agree that a heading on cosmetic usage would be fine so long as it is clear that it's not a medical application? Mentor Talk Contributions 14:19, 15 July 2020 (UTC)

"Aging" or "antiaging" are medical effects, as shown here where the editor community has deemed the topic with a B rating of high importance in WP:MED. People use retinol skin creams with intent to change the biology of their skin, a medical effect. We should follow the FDA guide and MEDRS-quality sources. This could be clarified in a subsection on cosmetics. You could go ahead with an edit, or post it here for review first by other editors. Zefr (talk) 14:35, 15 July 2020 (UTC)

I am not sure where on that page (anti)ageing is defined as a medical effect, but that is probably a fault on my part. I will try to formulate a thoughtful yet compliant paragraph that stresses the lack of medical evidence. — Preceding unsigned comment added by MPalokaj (talkcontribs) 15:08, 15 July 2020 (UTC)

This article is still mostly about vitamin A[edit]

Rising vote of thanks to Turjan for removing actually false claims related to carotenoids being retinoids.

That said, this article still seems to be mostly about vitamin A and not about retinol per se. We have a whole article on vitamin A, and that is where most of the material belongs.

If this article is to remain separate, it should be drastically scaled back so that it is primarily a chemistry article. The biology and nutrition component should all be moved to vitamin A. Otherwise, we should consider a merge into vitamin A. --Trovatore (talk) 22:52, 3 March 2019 (UTC)

I agree -- this article requires a lot of work. There are already extensive articles on Vitamin A and Carotenoids and that is where much of this information belongs. I tried to remove the most blatantly false information I could find, but there is still a lot more information here that is equally relevant to all forms of "Vitamin A", a term which sloppily includes both actual Vitamin A and its precursors (carotenoids). I don't think a merge is appropriate. There is enough good information specific to each of these things (Vit A, retinoids, carotenoids) that separate articles are more appropriate. I think what happened here is actually the result of conflating the common (incorrect, imo) understanding of "Vitamin A" which includes beta-carotene, by originally making Vitamin A a redirect to this retinol article. This resulted in a lot of junk related to carotenoids being added to this article, which only causes confusion.
It is actively dangerous and harmful to people for this article to contain false information claiming that retinoids are found in plants. From what I've read, conversion rates for carotenoids within the human body are widely variable, as low as 0% in some cases depending on health status, genetics, age, and various co-factors involved in digestion (presence of fat in a meal containing carotenoids). The estimates for conversion rates for carotenoids have been repeatedly revised downwards, and are still mostly guesswork. Pre-formed vitamin A (retinol) doesn't create a risk of Vitamin A deficiency caused by people making false assumptions about how well they, or their children are able to convert beta-carotene. It is highly undesirable for people to start thinking they can get true Vitamin A (retinol) from things like fruit, green leafy vegetables, or carrots based on misinformation in this wikipedia article! Turjan (talk) 23:37, 3 March 2019 (UTC)
Well, whether "vitamin A" includes carotenoids or not seems to be largely an question of English usage, and I gather that it varies somewhat by discipline, with nutritionists tending to include them and physiologists tending not to. Whether they count as "vitamin A" or merely "pro-vitamin A" is an issue that I think can reasonably be discussed at the vitamin A article, with references. I am not an expert in the issues that you raise.
My concern here is that retinol is only one chemical. Not only does it not include carotenoids; it does not include even closely related substances derived from animal sources. Therefore I think it's inappropriate to host the nutritional/physiological information, which applies to a wide spectrum of chemicals, at an article titled by the name only one of those chemicals. --Trovatore (talk) 00:52, 4 March 2019 (UTC)