Talk:Vitamin C/Archive 3

Term and label confusion
The terms Vit-C and Ascorbic Acid are often used interchangeably and it appears this is quite misleading. From what I am learning Vit-C is properly called L-ascorbate or L-ascorbic acid, and is a specific ion of ascorbic acid. The difference referred to only by the readily overlooked "L" (referring to the specific ion) appears to me to be quite significant. However, the article seems to (perhaps high-handedly in my opinion) promote the muddling by adopting a (probably academically correct) typography (upper case "L" in smaller point size and different typeface with an upper case "A") that makes the necessary distinction almost invisible to a non-technical/academic reader. I've made a minor change to the first paragraph to calrify the distinction from the outset but in my opinion the typography in general should changed from the academic/technical to the general, to align with the mission and readership of Wiki. I also think that the term L-ascorbate could be used, in preference to L-ascorbic acid (assuming that would still techically correct), to avoid promoting the muddle. Thes minor quasi-typographic changes in my opinion would maintain the distinction between the ion (Vit-C) and the base chemical (ascorbic acid). LookingGlass (talk) 07:23, 6 July 2012 (UTC)
 * Okay, this is complicated. The capital A "Ascorbate" is never correct, as this is not a proper noun. So unless there's some other reason to capitalize it, it's ascorbate. Ascorbate and ascorbic acid are different substances, as one is the anion of the acid, like nitric acid and nitrate. Both of them are present in the body in equilibrium acording to the pKa and the body's pH inside cells. All soluble salts of ascorbic acid, as well as the free acid itself, have vitamin C activity and thus are vitamers of vitamin C. Probably this article should try to use "ascorbate" whereever it uses the "a" word since it is simply shorter. As the article details, Szent-Györgyi suspected that hexuronic acid from adrenals might be the vitamin C known from animal assays, but he didn't know the stereochemistry even of this substance, although he had a sample made from adrenals. That was finally proven when Haworth synthesized L-hexuronic acid, a sugar, in 1933, and proved that THIS was vitamin C, not D-hexuronic acid (this chemist was the great Haworth of Haworth projections, so he surely knew what steroisomer he was working with). The L comes from the stereochem in D-glucose (dextrose) which carries over, when this stuff is made enzymatically in the body from dextrose (D-glucose), as D-glucose goes to L-gulonolactone. Szent-Györgyi and Haworth proposed that this stuff be called ascorbic acid (in honor of its vitamin activity, which the D-ascorbate largely lacks) and so when you see ascorbic acid, it means L-ascorbic acid and not D-ascorbic acid. Just as "glucose" means D-glucose and not L-glucose. However, the conventions of sugar chemistry demand that when there are enantiomers possible for any chemical, you should write which enantiomer is meant. Thus, chemically, the stuff is L-ascorbic acid. D-ascorbic acid is not found in nature, but can be made, and (interestingly) is nearly worthless as a vitamin (although of course just as good as an antioxidant, since oxygen and free radicals don't care about enantiomerism). So D-ascorbate is NOT a vitamer, and is not vitamin C. We probably should not write L-ascorbic acid except when defining this (as in the lede) and when talking about the chemistry of the molecule. It's also a proper name for the Ascorbic acid wiki, but they decided not to do it, due to problems with the D, which should be capitalized but small case and bolded. So the Wiki is Ascorbic acid but only because Wikis titles are capitalized AS titles. The term ascorbic acid links fine, since links are not cap sensitive. Finally, with all sugars it is standard that the D or L for mirror-image sugar stereoisomers (enantiomers) to be bolded and written upper-case, but a type-size smaller. So, technically, we should always write  L -ascorbate. But this is a lot of trouble, and it hasn't been done even in all the instances where  L -ascorbate is proper, since the chemical is being discussed. Okay? I'll try to fix some of this in the article, so some problems may be gone when you read this. I'll refer to here on TALK for the rationale.  S  B Harris 00:02, 12 July 2012 (UTC)

Antidepressant?
This article belongs to the "Antidepressants" category, however the article itself doesn't say anything about this except that depression may arise as a symptom from scurvy. I think either the category tag should be removed, or some info regarding vitamin C as an antidepressant should be added to the text. ✎ HannesP · talk 20:59, 1 November 2012 (UTC)


 * Agreed, category removed. --Daffydavid (talk) 05:54, 2 November 2012 (UTC)

Heat
Heat destroys Vitamin C ? — Preceding unsigned comment added by Vwalvekar (talk • contribs)
 * You'll probably have to be more specific with your question. Is this related to specific content of the article?  Are you asking if vitamin C can be burned?  Deli nk (talk) 19:40, 12 December 2012 (UTC)

Antioxidant vs Enzymatic cofactor
The article states "However, the fact that the enantiomer D-ascorbate (not found in nature) has identical antioxidant activity to L-ascorbate, yet far less vitamin activity,[3] underscores the fact that most of the function of L-ascorbate as a vitamin relies not on its antioxidant properties, but upon enzymic reactions that are stereospecific."

Ascorbate is used to regenerate Vit E and glutatione. Granted, this is an enzymatically mediated process. But it seems like its result is also to improve the body's anti-oxidant activity. The current wording, while technically accurate, is potentially confusing.

Interaction of ascorbate and alpha-tocopherol. http://www.ncbi.nlm.nih.gov/pubmed/3304060

Tocopherol and glutathione also rely on AA for regeneration back to their active isoforms. http://www.exrx.net/Nutrition/Antioxidants/VitaminC.html

--Ryan W (talk) 12:48, 3 April 2013 (UTC)

Should the reference be removed
Reference 132 isn't relevant and I think it might need to be removed. I may be wrong so I am asking for someone to check it out. Basically the link is working perfectly fine but doesn't seem relevant to what it is referencing. Richboy999 (talk) 02:52, 17 September 2013 (UTC)
 * No, the reference is fine, the article uses the latin name not the common name. The latin name can be found at the common name page by clicking on the link. --Daffydavid (talk) 08:22, 17 September 2013 (UTC)

Error in article

 * As vitamin C enhances iron absorption, [114] iron poisoning can become an issue to people with rare iron overload disorders, such as haemochromatosis. A genetic condition that results in inadequate levels of the enzyme glucose-6-phosphate dehydrogenase (G6PD) can cause sufferers to develop hemolytic anemia after ingesting specific oxidizing substances, such as very large dosages of vitamin C.

It's not vitamin C that increases iron absorption, only ascorbic acid does. Otherwise please add sources describing the iron uptake with e.g. sodium ascorbate (that is also vitamin C!). Or change above sentence into "As ascorbic acid enhances iron absorption..." --178.197.236.179 (talk) 02:14, 21 October 2013 (UTC)

Toxicity of ascorbic acid and "Upper Intake Level"
Am I right that animals produce not ascorbic acid but only sodium ascorbat in their liver? This would explain why some people have toxic effect by taking several grams of ascorbic acid: They should take sodium ascorbate instead, because only ascorbate is bioavailable. --178.197.236.179 (talk) 02:22, 21 October 2013 (UTC) By the way the described "Tolerable Upper Intake Level" is for ascorbic acid and not sodium ascorbate. You can take about 25 grams sodium ascorbate daily without any problems. The amount of sodium ascorbate produced in a human without the genetic mutation would be 15-25 grams for an adult. --178.197.236.179 (talk) 02:30, 21 October 2013 (UTC)

New study on Vitamin C intravenous therapy seems to confirm efficiency
-- megA (talk) 22:45, 9 February 2014 (UTC)
 * Actually, the study says it warrants further study in clinical trials, not that it has any proven efficacy (I assume you meant efficacy, not efficiency). Yobol (talk) 22:54, 9 February 2014 (UTC)
 * Yes, I just noticed that. Leave it to BBC News to raise hopes... -- megA (talk) 23:03, 9 February 2014 (UTC)

Reliability of the plant source table
I removed an entry stating that the "Mica Muro" contained 500mg/100g. The entry was added in |this edit from August 2011, by an IP that has never made any other edits, and was unsourced. The term does not exist on Wikipedia, and a search for this term elsewhere only seems to bring up lists taken from Wikipedia itself. The entry has been widely cited over the past few years. It appears to be a fake entry that has remained unspotted for 3 years. The source given for the list itself is no longer at the link provided, so the entire table may contain dubious info. Greenman (talk) 19:12, 14 August 2014 (UTC)

Severe error on animal products.
It has huge amounts of C, the issue is that when cooked it loses some of it. Most of these "studies" fail to realize that. --193.92.17.25 (talk) 13:03, 31 August 2014 (UTC)


 * That depends on how it's cooked. Why don't you do done research instead of repeating misconceptions? Nobody ever got scurvy from living on cooked fresh meat. They got it from just hardtack, or rice, or long dried or jerked meat, or canned food, which is far more severely treated.  S  B Harris 18:56, 31 August 2014 (UTC)

Reorganization of article suggested
I suggest to reorganize this article. There should be main sections about Biosynthesis and Physiology. I would also merge 2.5 Supplementation, 5 Daily requirements,  and 8 Dietary sources into one section such as "Vitamin C in (human?) diet". Alternatively, 2.5 Supplementation could be combined with 7 Adverse effects as the former almost exclusively deals with medical conditions. The section on Evolution doesn't make sense as Vitamin C doesn't evolve. The only thing that does evolve are the enzymes (or their encoding genes) that are involved in Vitamin C metabolism. Peteruetz (talk) 23:46, 19 November 2014 (UTC)
 * The section you propose on physiology by the same logic also does not makes sense. Vitamin C is a chemical. It is not alive and has no physiology. Do you want to waste our time being super-literal? S  B Harris 02:33, 20 November 2014 (UTC)

Where to put E number?
The E number for Vitamin C (E300) is missing. What would be a good place to put it? Under "identifiers", maybe? --Benimation (talk) 16:19, 4 April 2015 (UTC)

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confusing wording: possible side effects
in the Possible Side Effects section this sentence: " ingesting specific oxidizing substances, such as very large dosages of vitamin C" seems to me both unclearly worded and in contradiction with the antioxidant property of vitamin-C (which is mentioned in the first section of the article). 178.164.137.95 (talk) 09:40, 15 September 2014 (UTC)

The statement in question is no longer in the possible side effects section. In the Dietary Reference Intake text there is speculation about whether vitamin C in large amounts can act as a pro-oxidant, but the evidence was very weak.David notMD (talk) 09:52, 8 May 2016 (UTC)

Deleting two sentences and a reference?
How do people feel about a proposal to delete the two sentences and a reference (see below) from Daily Requirements? The recommendation from the reference (1000 mg) is radically different from every government position on this vitamin. The journal in question has a low Impact Factor.David notMD (talk) 15:02, 22 March 2017 (UTC)

"There is continuing debate within the scientific community over the best dose schedule (the amount and frequency of intake) of vitamin C for maintaining optimal health in humans. A 2008 review recommended 1,000 mg/day as a supplement, in addition to what is consumed from food.


 * I suggest toning down the language to:
 * Not all agree about the amount and frequency of Vitamin C supplementation.
 * Best Regards,
 * Barbara (WVS) ✐   ✉  15:45, 22 March 2017 (UTC)


 * Delete both sentences. The citation is unreliable, and I see no need for the replacement sentence at all. -Roxy the dog. bark 16:11, 22 March 2017 (UTC)
 * Given how emotional editors get about vitamin C, thinking I will wait a week to see who else weighs in before going through with a change.David notMD (talk) 16:16, 22 March 2017 (UTC)
 * I agree the content and source should be removed as weak and unreliable. Although the US-Canada RDI of 60 mg/day is based on conservative, expert review by the US Institute of Medicine on behalf of the FDA, it is low compared to the 80-90 mg/day by EFSA, while other vitamin C expert opinion by the Linus Pauling Institute of Oregon State University recommends 400 mg/day which can be achieved by combining fresh fruit and vegetable consumption with a dietary supplement. --Zefr (talk) 16:23, 22 March 2017 (UTC)
 * Zefr - take care not to conflate DRIs (which include RDAs) with RDIs, the latter being what food and supplement label % Daily Values are based on. RDAs have been changed over years, but until May 2016 RDIs were stuck at what was set in 1979. For vitamin C, male RDA is 90 mg, female RDA 75 mg, the old RDI was 60 mg, the new RDI 90 mg. As a general rule, the new RDIs match the highest RDA. Companies have until July 2018 for labels to comply with the new RDIs.David notMD (talk) 01:04, 23 March 2017 (UTC)
 * Understood, . From the FDA guidance for labeling here, the statement reads "In order to limit consumer confusion, however, the label includes a single term (i.e., Daily Value (DV)), to designate both the DRVs and RDIs" where the Daily Value for vitamin C is 60 mg/day. Given the quantitative different vitamin C recommendations of DRV-DRI-RDA-RDI-DV, it's as clear as mud. But the DV is the value consumers see on product labels, and so is arguably the easiest guidance to understand in an encyclopedia. --Zefr (talk) 01:18, 23 March 2017 (UTC)
 * And in 16 months 100% DV will be 90 mg. Where it's confusing is that some companies with long shelf life products are already implementing the changeover.David notMD (talk) 03:04, 23 March 2017 (UTC)
 * Done. Point is now moot. Thx. -Roxy the dog. bark 16:25, 22 March 2017 (UTC)

Nominate as a Good Article?
Vitamin C became a Good article in 2007, then delisted in 2010. Has there been enough improvement that it should be reconsidered? David notMD (talk) 15:32, 2 September 2017 (UTC)
 * Working through the citations to collapse duplicated referencing, improve on old, revive or replace dead links, etc. Complying with MEDRS. David notMD (talk) 15:48, 5 October 2017 (UTC)
 * Would be nice if there was an animal kingdom biosynthesis image. Commons has an industrial synthesis image, but not appropriate for this article. David notMD (talk) 18:44, 6 October 2017 (UTC)
 * COI issue: Today, nominated Vitamin C for Good Article. As a science consultant to dietary supplement companies I have clients that sell vitamin C containing products. None of them have asked me to edit the vitamin C article, nor are aware that I am doing so. This is true for all of my actions on nutrition articles. David notMD (talk) 13:17, 13 October 2017 (UTC)

Refs
Generally I put the full ref in the lead to make translation easier. Therefore returned. Doc James (talk · contribs · email) 00:53, 27 November 2017 (UTC)

Mechanism of action
Is important for both dietary and supplement use. Therefore it should go later in the article in my opinion, similar to what we do with vitamin D. Doc James  (talk · contribs · email) 01:05, 27 November 2017 (UTC)

Ref
"The history of vitamin C is closely tied to seagoing voyage. After months at sea, sailors became afflicted with a disease that came to be named scurvy. Navy surgeons, among them James Lind of the British Navy, confirmed that foods such as lemons, limes, oranges and cabbage would prevent the disease. From 1928 to 1932, Albert Szent-Györgyi and others worked to isolate the antiscorbutic compound and identify its chemical structure. "

A ref more recent than 1932 would be useful. Doc James (talk · contribs · email) 02:38, 28 November 2017 (UTC)

Biology
We place a section on "biology" for substances that are both an important molecule normally within humans and are a medication.

In this situation this substance is not make within humans but is either dietary or a supplement. Doc James (talk · contribs · email) 03:33, 28 November 2017 (UTC)

Does not belong as the first paragraph
IMO this should not be the first paragraph of the the article.

"The loss of biosynthesis capacity occurred multiple times in evolution, as it is lacking in humans, some primates, most fish, most bats, some birds and guinea pigs. Species unable to synthesize vitamin C get it from food. Vitamin C performs numerous physiological functions, including the synthesis of collagen, carnitine, and neurotransmitters. Vitamin C is found in high concentrations in cells of the immune system and is depleted quickly during infections, implying an essential role in immunity.

The Linus Pauling Institute is slightly controversial in that he promoted high dose vitamin C.

Usually we put stuff about importance in other animals lower in the article. That the ability to make the substance was lost multiple times during evolution is also not key

We already mention it is important in tissue repair in the second paragraph. Doc James (talk · contribs · email) 02:48, 28 November 2017 (UTC)
 * We should get over this apprehension that Pauling's eccentricity is somehow still influencing LPI article content per this. Pauling has been dead for 23 years, and the current LPI faculty who write the nutrient and phytochemical articles compete for and evidently win grants like other university research faculty. There are few/no other university research centers that publish similar high-quality, comprehensive and updated reviews on nutrients. --Zefr (talk) 03:18, 28 November 2017 (UTC)
 * Okay, reading and agree it is a decent review. Doc James  (talk · contribs · email) 03:46, 28 November 2017 (UTC)

Smoking and the RDA
The increased dietary requirement of vitamin C in smokers should be mentioned in this article.  Seppi  333  (Insert 2¢) 06:39, 31 December 2017 (UTC)
 * Just to clarify, indicates that pregnant smokers may require double the RDA; both refs indicate that smokers need an additional 35 mg of vitamin C per day relative to non-smokers. Both refs are currently cited in the article.  Seppi  333  (Insert 2¢) 01:34, 1 January 2018 (UTC)
 * Interesting question. As noted, the U.S. IOM states that smoking lowers plasma vitamin C concentration, and suggests that an additional 35 mg/day is warranted. But this is not formally recognized as a separate RDA for smokers. Japan acknowledged the same topic, but does not specify the amount needed to compensate. For India, EU and World Health Organization no mention of smokers. The article PMID 25145261 concluded that higher vitamin C intake lowers risk of lung cancer. David notMD (talk) 03:14, 1 January 2018 (UTC)
 * Added text on smokers, citing U.S. DRI and that meta-analysis. David notMD (talk) 10:11, 1 January 2018 (UTC)
 * Looks good! Thanks.  Seppi  333  (Insert 2¢) 22:35, 2 January 2018 (UTC)

Did You Know
A DYK for Vitamin C is now in Prep: "...that in 1934 vitamin C was the first synthetic vitamin to be trademarked (as Redoxon) and marketed?" So for any further editing of the first paragraph in the Discovery section. please don't delete the text and citations that support this. David notMD (talk) 01:26, 5 January 2018 (UTC)

"Made" versus "synthesized"
Both mean the same and thus IMO the first is fine in the lead. Doc James (talk · contribs · email) 08:14, 5 January 2018 (UTC)
 * The verb "made" without context is too ambiguous. It could be "made" internally in humans (biosynthesized), "made" in a plant or other non-animal species (e.g., a bacteria or fungus) and extracted, "made" via chemical reactions, or via another method.  The context needs to be clarified if you're going to use that verb instead.  Seppi  333  (Insert 2¢) 08:30, 5 January 2018 (UTC)
 * Disagree... Synthesized is more apt to be interpreted as biosynthesis versus externally synthesized.


 * Your thought on this "Vitamin C was discovered in 1912, isolated in 1928, and in 1933 was the first vitamin to be chemically produced." ? Doc James (talk · contribs · email) 08:52, 5 January 2018 (UTC)
 * IMO, with the Wikilink to chemical synthesis there should be no confusion. In the Discovery section, first paragraph, I deleted the word "semi-synthetic" as a description of mass production. While true (there is a bacterial fermentation step), it was confusing following so closely after the sentence about vitamin C being the first vitamin to be synthesized. David notMD (talk) 15:52, 5 January 2018 (UTC)
 * I like the phrasing from your most recent revised version more than any of the previous revisions, so I'm happy to keep it as is. It's clear and concise.  Seppi  333  (Insert 2¢) 03:39, 6 January 2018 (UTC)

I also suggest we all study the definition of pilpul David notMD (talk) 19:21, 5 January 2018 (UTC)
 * Writing in easier to understand English is an entire profession... Doc James  (talk · contribs · email) 06:55, 6 January 2018 (UTC)

Significance section under Biology needs rewrite
The Significance section is poorly written. I had intended to do a complete rewrite as part of the Good Article process, but there was a push to bring that to closure. Still my intention. I have posted the replaced version below (yes, I know I wrote I was going to post the proposed text here first, but I didn't). A reminder - as I stated when I began the GA process, I have a COI, in that I am a science consultant to companies in the dietary supplement industry (none of whom are aware that I am a Wikipedia editor). My approach here is to adhere to NPOV. David notMD (talk) 16:01, 5 January 2018 (UTC)


 * Deep breath. Significance section shortened to get rid of repetition of information. Replaced text saved below. Only ref not kept in this section or elsewhere was Padayatty. Levine and Pollack now referenced only elsewhere. Please do not revert without discussing here in Talk first. David notMD (talk) 01:46, 8 January 2018 (UTC)

Vitamin C is an essential nutrient for certain animals including humans. Vitamin C describes several vitamers that have vitamin C activity in animals, including ascorbic acid and its salts, and some oxidized forms of the molecule like dehydroascorbic acid. Ascorbate and ascorbic acid – represented by the collective term, vitamin C – are both naturally present in the body when either of these is introduced into cells, since the forms interconvert according to pH. Vitamin C is a cofactor in at least eight enzymatic reactions, including several collagen synthesis reactions that, when dysfunctional, cause the most severe symptoms of scurvy. In animals, these reactions are especially important in wound-healing and in preventing bleeding from capillaries.

The biological role of vitamin C is to act as a reducing agent, donating electrons to various enzymatic and non-enzymatic reactions. The one- and two-electron oxidized forms of vitamin C, semidehydroascorbic acid and dehydroascorbic acid, respectively, can be reduced in the body by glutathione and NADPH-dependent enzymatic mechanisms. The presence of glutathione in cells and extracellular fluids helps maintain ascorbate in a reduced state.

In humans, adequate vitamin C intake results from consumption of raw plant foods or fortified foods, providing antioxidant functions from its ability to donate electrons, and so lessen oxidative stress. Vitamin C is an enzyme cofactor for the biosynthesis of many biochemicals required for normal metabolism. It is a substrate for ascorbate peroxidase in plants. This enzyme utilizes ascorbate to neutralize toxic hydrogen peroxide (H2O2) by converting it to water (H2O).

Vitamin C is required for a range of essential metabolic reactions in all animals and plants. Although it is made internally by almost all vertebrates, there are exceptions which do not synthesize it, including humans, tarsiers, and monkeys.

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D-ascorbic acid
The redirect, which currently targets Vitamin C, has been nominated for deletion at Redirects for discussion/Log/2018 May 19. You are invited to contribute to that discussion as comments from those who understand the subject would be beneficial. Thryduulf (talk) 12:58, 19 May 2018 (UTC)

Pharmacodynamics
I was trying to verify the number of enzymes that vitamin C acts as a cofactor for, so I went to a random enzyme page which utilizes it as a cofactor (DA beta-hydroxylase) and checked the GO terms for ones that appeared relevant. Correct me if I'm wrong, but don't the definitions for ("L-ascorbic acid binding") describe activity as a cofactor and  (really long descriptor) describe a specific form of activity as a substrate?

If the former GO term does describe a cofactor interaction, then it looks like there's 20 human enzymes or enzyme subunits for which vitamin C serves as a cofactor, not just the 8 that are listed in this article in Vitamin C. Based upon Cofactor (biochemistry), I'd assume it acts as an electron donor at all of those enzymes/subunits, although I'm not sure how to easily verify that.  Seppi  333  (Insert 2¢) 13:15, 23 December 2018 (UTC)
 * Actually, I just noticed is listed under, so I guess that answers my question about the former GO term. Edit: My question about the second GO term is sort of moot considering that there's only 2 other human genes listed under it (PAM and MOXD2P). Is there an easy way to verify whether or not ascorbate acts as an electron donor for the 20 enzymes/subunits listed for Homo sapiens in ?  Seppi  333  (Insert 2¢) 13:26, 23 December 2018 (UTC); edited 13:58, 23 December 2018 (UTC)

Nevermind. I'm just putting this table here for cross-referencing later.  Seppi  333  (Insert 2¢) 15:11, 23 December 2018 (UTC)


 * Maybe add table 1 from (Immune function).
 * Cover Regulation of the Epigenome by Vitamin C and The role of vitamin C in epigenetic regulation (Epigenetics).
 * Include PHYH in the list of enzymes (UNIPROT).
 *  Seppi  333  (Insert 2¢) 22:55, 28 December 2018 (UTC)

First sentence
The first sentence should be write in easier to understand language:

1) "Vitamin C is a vitamin, the chemical compound ascorbic acid C6H8O6, specifically the enantiomer L-ascorbic acid."

is significantly more complicated than

2) "Vitamin C, also known as ascorbic acid and L-ascorbic acid, is a vitamin found in food and used as a dietary supplement"

Doc James (talk · contribs · email) 22:33, 8 October 2018 (UTC)


 * Mostly agreed.--Jorge Stolfi (talk) 16:27, 9 October 2018 (UTC)

Also generally we organize the lead such that it follows the layout of the body of the text.


 * There is no such rule. Rather, the lead paragraph should convey the most important information about the topic, in whichever way and order is more readable and helpful to the readers.--Jorge Stolfi (talk) 16:27, 9 October 2018 (UTC)
 * Vitamin C is famous for preventing scurvy. The most common use is to try to prevent colds. The other uses are less common. Thus the ordering for medical uses. Doc James  (talk · contribs · email) 01:20, 11 October 2018 (UTC)

Common cold
This is key "Evidence does not support use in the general population for the prevention of the common cold."

With this by itself being undue "There is, however, some evidence that regular use may shorten the length of colds."

Doc James (talk · contribs · email) 22:39, 8 October 2018 (UTC)


 * Both claims were in the original article, I barely rearranged them. --Jorge Stolfi (talk) 16:27, 9 October 2018 (UTC)

Scurvy
Per "Deficiency of vitamin C causes scurvy, which used to plague sailors in long voyages until the 18th century."

The issue in sailors belong in the article on scurvy. And it did not "plague" sailors but commonly affected them. Doc James (talk · contribs · email) 22:40, 8 October 2018 (UTC)


 * The details of scurvy of course belong in its own article, but the connection between vitamin C and long sea voyages is the single most important historical fact about the vitamin. In many such expeditions the majority of the sailors died from it.  "Affected" does not quite convey the severity pf the disease... --Jorge Stolfi (talk) 16:27, 9 October 2018 (UTC)


 * As a person with a doctorate in nutritional biochemistry, and more to the point, the person who brought this article from C-class to Good Article, I agree with Doc James. And I will add that Doc James does more than 15,000 edits per year on medical/medicine/health topics, and has a good understanding of what is appropriate wording. David notMD (talk) 17:38, 9 October 2018 (UTC)
 * Apologies for the bother. I will be careful not to edit articles owned by this Wikiproject in the future. --Jorge Stolfi (talk) 18:15, 12 October 2018 (UTC)
 * As you well know, there is no "own." Were I to edit in your area of expertise I would defer to those versed in that field. David notMD (talk) 23:11, 12 October 2018 (UTC)

Why cancer ref removed?
This ref and the text with it were removed. Why? It is a relatively recent meta-analysis. Luo J, Shen L, Zheng D (August 2014). "Association between vitamin C intake and lung cancer: a dose-response meta-analysis". Scientific Reports. 4: 6161. Bibcode:2014NatSR...4E6161L. doi:10.1038/srep06161. PMC 5381428. PMID 25145261. David notMD (talk) 22:45, 7 December 2018 (UTC)
 * Chinese research making extraordinary claims in a somewhat dodgy journal: WP:REDFLAG. Alexbrn (talk) 05:42, 8 December 2018 (UTC)
 * Authors were mainland China researchers, but this is a meta-analysis of 18 clinical trials conducted in many countries (12 in USA, only 2 in China). The authors of the meta-analysis were not co-authors of either of the trials reported from China, and the two China (Singapore) trials did not differ from the results of the meta-analysis as a whole. The journal itself is from the publishers of Nature "Scientific Reports is an online, open access journal from the publishers of Nature. We publish scientifically valid primary research from all areas of the natural and clinical sciences. Visit this page to find out about the quality, rigour, reach and service offered by Scientific Reports. The 2017 journal metrics for Scientific Reports are as follows:2-year impact factor: 4.122; 5-year impact factor: 4.609; Immediacy index: 0.576; Eigenfactor ® score: 0.71896; Article influence score: 1.356; 2-year median: 2." In my opinion this does not rise to the level of REDFLAG. David notMD (talk) 11:54, 8 December 2018 (UTC)
 * I am well aware of Scientific Reports - it is garnering a reputation as the go-to journal for junk science (see e.g.) and is completely distinct from Nature (though we've had many instances here of people claiming a SR article is somehow in Nature). The WP:REDFLAG lies in the fact that it is widely accepted that Vitamic C is not helpful for cancer therapy (indeed, it has a reputation as a scam). Something that overturns that understanding need to be super-strength - ideally we'd need multiple sources. Alexbrn (talk) 12:19, 8 December 2018 (UTC)
 * This is not a therapy claim article (which I agree would be contrary to consensus science), but rather a prevention claim. I add that a meta-analysis conducted by Canadian researchers reported an Odds Ratio of 0.74 for vitamin C and lung cancer. See: Shareck M, Rousseau MC, Koushik A, Siemiatycki J, Parent ME. Inverse Association between Dietary Intake of Selected Carotenoids and Vitamin C and Risk of Lung Cancer. Front Oncol. 2017 Feb 28;7:23. doi: 10.3389/fonc.2017.00023. eCollection 2017. PubMed PMID: 28293540; PubMed Central PMCID: PMC5328985. Will you accept that as a second source? David notMD (talk) 14:57, 8 December 2018 (UTC)
 * A Frontiers Media journal? Doesn't that rather compound the worry? Alexbrn (talk) 15:14, 8 December 2018 (UTC)
 * Wait, you want those to carry more weight than the Cochrane review (or the one in 2003) that concluded "There is no evidence for recommending supplements of vitamins A, C, E, selenium, either alone or in different combinations, for the prevention of lung cancer and lung cancer mortality in healthy people"? Proponents of vitamin C are going to need a lot of evidence to overturn consensus, not just some meta-analyses in questionable journals. --tronvillain (talk) 15:25, 8 December 2018 (UTC)
 * The Cochrane 2013 review was specific to use of supplements. It included only three vitamin C studies. And it is already in the body of the article - because I put it there. My point here is that there should be a way to incorporate one (now two) meta-analyses with a larger pool of studies which present results in favor of higher vitamin C intake reducing risk of cancer. David notMD (talk) 15:40, 8 December 2018 (UTC)
 * Better sources on this topic are needed before anything can be included. Alexbrn (talk) 15:49, 8 December 2018 (UTC)

I apologize for stating that Shareck was a second meta-analysis. I did a PubMed limited to meta-analyses, but the search yield still puts a few articles in a box at the top that are NOT meta-analyses. My only excuse for not catching this is - pre-coffee moment. Given an older review of prospective studies [Cho E, Hunter DJ, Spiegelman D, Albanes D, Beeson WL, van den Brandt PA, Colditz GA, Feskanich D, Folsom AR, Fraser GE, Freudenheim JL, Giovannucci E, Goldbohm RA, Graham S, Miller AB, Rohan TE, Sellers TA, Virtamo J, Willett WC, Smith-Warner SA. Intakes of vitamins A, C and E and folate and multivitamins and lung cancer: a pooled analysis of 8 prospective studies. Int J Cancer. 2006 Feb 15;118(4):970-8. PubMed PMID: 16152626] did not support vitamin C reducing lung cancer risk, I will leave the article as it stands. David notMD (talk) 18:27, 8 December 2018 (UTC)

Evolution section needs some work
Another section that should have been revised as part of the Good Article process. It has nothing about vitamin C in single-cell organisms, fungi or plants. As exists, repetitive and perhaps overlong on what happened in primates. David notMD (talk) 14:33, 8 January 2018 (UTC)
 * Still needs work. David notMD (talk) 15:47, 8 October 2018 (UTC)
 * Deleted a paragraph and two references as speculation about the consequences of primates losing capacity to synthesize ascorbic acid. David notMD (talk) 10:30, 23 December 2018 (UTC)

Use before mechanism
How vitamin C "works" ie it "is an essential nutrient involved in the repair of tissue and the enzymatic production of certain neurotransmitters" should go lower in the lead rather than the first paragraph in my opinion.

This is its mechanism of action and is fairly complicated. I also believe people are less interested in these details than that about the common cold. Doc James (talk · contribs · email) 02:51, 23 December 2018 (UTC)
 * I don't think what you've stated above is accurate. The content I added to the first paragraph was not about its mechanism; it was about its function. I didn't list any enzymes, I simply stated what purpose it serves in the body. In any event, I reverted your edit. When you reverted mine, you stated in your edit summary that the lead should follow the body.  Observe where we cover Vitamin C.  Seppi  333  (Insert 2¢) 11:22, 23 December 2018 (UTC)

Given that both of you are eyeballing this article, I am again suggesting that sentences in the lead such as "In 2015, the wholesale cost in the developing world was less than US$0.01 per tablet.[13]" feel to me like a static, non-informative fact. Similar sentences in other vitamin articles. Cost not further discussed in body of those article. DJ and I have been on opposite sides of this debate in the past. David notMD (talk) 11:39, 23 December 2018 (UTC)
 * I deleted that clause per my edit summary. @Doc James: I don't really mind that you've added that stuff to most drug articles, but there's almost no point in including price data for vitamin products that are that are regulated and sold as drugs in articles on vitamins unless there's something that differentiates it from vitamin-containing OTC drug products and vitamin supplements (e.g., if the dosage form is an injection).  Seppi  333  (Insert 2¢) 15:29, 23 December 2018 (UTC)
 * Well lets just call it inexpensive than. We have high quality sources for the price in the UK and the developing world. Doc James  (talk · contribs · email) 01:12, 24 December 2018 (UTC)

I am against cost per treatment for any vitamin or mineral. A point I want to state here even though I may not attempt to incorporate this approach into the various vitamin articles: vitamin C deficiency to the point of scurvy is historically true but extremely rare in current world conditions. Thus, undue focus on need for vitamin C as a medically prescribed product, and no need to discuss a cost per daily treatment in this article. Other vitamins - folate, vitamin A... - have clearly been identified as needed to prevent or treat commonly occurring deficiency status in individuals, with known medical consequences if not treated, so a cost per daily (or other) prevention treatment in countries where such deficiencies are a matter of public health policy would be appropriate for those articles. There are also prescription treatments for diagnosed deficiencies (injected iron, high dose vit D, etc.). Even for these, I am against cost per treatment, but will not oppose. David notMD (talk) 13:12, 24 December 2018 (UTC)

Captive primates and Vitamin C
One source says the legal daily level for captive apes is 5,000 mg per day (the source froze up on me and I had to restart the computer), and in the past I've read that captive apes in the U.S. had to be given the human equivalent (per weight) of 3,200 mgs per day. Does anyone know the actual legal requirements? The mg recommended doses for humans is ridiculously low, and a comparison with recommended (or legally required) doses for captive gorillas, chimpanzees, and other primates would be an interesting addition to the page (unless it is there already and I'm missing it). Randy Kryn (talk) 14:23, 23 December 2018 (UTC)
 * My uninformed guess is that non-human primates have a much higher vitamin C intake on a body weight basis than humans, but not clear if this is a result of diet or a different requirement. A possible lead on the topic: Milton K. Micronutrient intakes of wild primates: are humans different? Comp Biochem Physiol A Mol Integr Physiol. 2003 Sep;136(1):47-59. Review. PubMed PMID:14527629. David notMD (talk) 15:47, 23 December 2018 (UTC)
 * , if you have a few minutes could you have a go at this to see what you can come up with? Thanks. The legal requirement for captive great apes per weight in the U.S. or UK should be easy to find, but I have screen-freeze issues researching the topic. Thanks. Randy Kryn (talk) 13:15, 26 December 2018 (UTC)
 * Some information at Nutrient Requirements of Nonhuman Primates: Second Revised Edition (2003) Chapter: 11 Nutrient Requirements https://www.nap.edu/read/9826/chapter/13  Table 11-2 shows recommendation of 200 mg vitamin C per kilogram diet (dry weight). This converts to close to recommended intakes for humans via this calculation - humans consume ~ 0.5 kg food per day (dry weight), so the 200 mg/kg would equate to 100 mg/day. The U.S. recommended intake for humans is 75 mg/day for adult females and 90 mg/day for adult males. Thus, a bit lower than what this one references states for primates, but not ridiculously off. There is also this book [Nutrient Requirements of Nonhuman Primates: Second Revised Edition By National Research Council, Division on Earth and Life Studies, Board on Agriculture and Natural Resources, Ad Hoc Committee on Nonhuman Primate Nutrition, Committee on Animal Nutrition] as a possible source, but not available on-line. David notMD (talk) 16:18, 26 December 2018 (UTC)

Pharmacodynamics
I was trying to verify the number of enzymes that vitamin C acts as a cofactor for, so I went to a random enzyme page which utilizes it as a cofactor (DA beta-hydroxylase) and checked the GO terms for ones that appeared relevant. Correct me if I'm wrong, but don't the definitions for ("L-ascorbic acid binding") describe activity as a cofactor and  (really long descriptor) describe a specific form of activity as a substrate?

If the former GO term does describe a cofactor interaction, then it looks like there's 20 human enzymes or enzyme subunits for which vitamin C serves as a cofactor, not just the 8 that are listed in this article in Vitamin C. Based upon Cofactor (biochemistry), I'd assume it acts as an electron donor at all of those enzymes/subunits, although I'm not sure how to easily verify that.  Seppi  333  (Insert 2¢) 13:15, 23 December 2018 (UTC)
 * Actually, I just noticed is listed under, so I guess that answers my question about the former GO term. Edit: My question about the second GO term is sort of moot considering that there's only 2 other human genes listed under it (PAM and MOXD2P). Is there an easy way to verify whether or not ascorbate acts as an electron donor for the 20 enzymes/subunits listed for Homo sapiens in ?  Seppi  333  (Insert 2¢) 13:26, 23 December 2018 (UTC); edited 13:58, 23 December 2018 (UTC)

Nevermind. I'm just putting this table here for cross-referencing later.  Seppi  333  (Insert 2¢) 15:11, 23 December 2018 (UTC)


 * Maybe add table 1 from (Immune function).
 * Cover Regulation of the Epigenome by Vitamin C and The role of vitamin C in epigenetic regulation (Epigenetics).
 * Include PHYH in the list of enzymes (UNIPROT).
 *  Seppi  333  (Insert 2¢) 22:55, 28 December 2018 (UTC)

General style
There is a lot of work put into this article in terms of reporting and comparing hard research. It would be nice to see a similar amount of attention paid to English style, if anyone has the inclination and time. The wording could be polished in many places. I mention it because this is turning into a good article and I would like to see more people reading it and enjoying the experience. Thanks. Alfarero (talk) 19:43, 9 January 2020 (UTC)
 * It has been a "Good Article" since November 2017. However, if there are ways to improve it further, do so. David notMD (talk) 20:30, 9 January 2020 (UTC)

Cardiovascular subsection needs work
I removed text and two refs from the Cardio subsection. One [Ye Y, Li J, Yuan Z (2013). "Effect of antioxidant vitamin supplementation on cardiovascular outcomes: a meta-analysis of randomized controlled trials". PLOS ONE. 8 (2): e56803. PMID 23437244] was there in error, as it is a meta-analysis of combinations of antioxidant vitamins rather than solely vitamin C. Moser 2016 was removed because the quote from the abstract was misleading - the article as a whole was mixed in its assessment of vit C and cardio. Newer references should be sought. David notMD (talk) 14:49, 14 March 2020 (UTC)

2013 PLOS review
It states "Antioxidant vitamin supplementation has no effect on the incidence of major cardiovascular events, myocardial infarction, stroke, total death, and cardiac death." and specifically looked at "Antioxidant vitamin (vitamin E, beta-carotene, and vitamin C)"

I guess we could just go with this Cochrane review https://pubmed.ncbi.nlm.nih.gov/28301692-vitamin-c-supplementation-for-the-primary-prevention-of-cardiovascular-disease/

The problem with this https://pubmed.ncbi.nlm.nih.gov/24284213-vitamin-c-intake-circulating-vitamin-c-and-risk-of-stroke-a-meta-analysis-of-prospective-studies/ is it is prospective studies not RCTs. So hypothesis generating and this hypothesis does not appear to be true.

Doc James (talk · contribs · email) 17:58, 14 March 2020 (UTC)

Serum vitamin C in different species
Much is made of non-primate species synthesizing more ascorbic acid than humans, and for some primates (gorilla) eating more than humans, but this article lacks a comparison of serum vitamin C across species. So far, have found mention that humans average 35-40 micromoles/L and cattle, 15 micromoles. Oddly, the article is also missing what is the normal range for humans, and a better definition of what are low and deficient serum values. David notMD (talk) 12:46, 20 March 2020 (UTC)
 * Found and added a ref for human serum concentrations for normal range, low and deficient. (Carr 2016). Also found NHANES report on % deficient in U.S. David notMD (talk) 13:29, 20 March 2020 (UTC)
 * Animal information is scare, but found a bit. Would have liked to have values for zoo and wild-living primates. Interestingly, dogs (could not find cats information) in same general rang as humans, whereas goats, sheep and cattle higher. David notMD (talk) 18:02, 20 March 2020 (UTC)

I am removing the image of the goat and the caption (again). My position is that the caption - by stating that goats synthesize very large amounts of vitamin C (large in comparison to recommendations for consumption by humans), and increase synthesis when stressed, implies that humans should be consuming more vitamin C than currently recommended by government organizations, especially when stressed ('stress' not defined). The goat ref is dated 1973 and behind a paywall. David notMD (talk) 11:10, 22 March 2020 (UTC)
 * , zoos which contain primates, such as chimpanzees, gorillas, monkeys, etc. have governmentally sanctioned regulations which specify the quantities of ascorbic acid that must be provided to these primates daily. These should be found, referenced, and added. The caption of the goat image explained that almost all other living beings continuously create ascorbic acid in their bodies. This data can also be added in an image of a gorilla or chimpanzee along with the governmental regulation when found. Unless I'm mistaken, many years ago the figure I recall is that zoos had to provide the human-weight equivalent of 3,200 mgs. daily. The books mentioned in the 2018 section above give some information, but the captive primate regulatory information seems essential for this discussion. Thanks. Randy Kryn (talk) 11:45, 22 March 2020 (UTC)
 * I have been searching for that information with no success so far. Not in science journal literature, nor general searches. Key information will be not just consumption but what serum concentrations are achieved. If simians consume far more than humans, but have similar serum levels, that argues against any rationale for higher intake for humans. Will continue to look. Any information on nutrient requirements of the great apes (chimps, gorillas, orangutans) will have to be tempered by the fact that our genetic divergence is millions of years, during which time the human species A) recycles vitamin C effectively, and B) has endogenous antioxidants. David notMD (talk) 14:45, 22 March 2020 (UTC)
 * Portman, O. (1970) recommends 25 mg/kg body weight for primates as an allowance (requirement plus an overage to make sure). Appears based on rhesus, but could be considered as reasonable for other primates. See TABLE V, page 97. For 70 kg chimpanzee, equals 1,750 mg/day. No information on serum levels or rationale. David notMD (talk) 15:17, 22 March 2020 (UTC) Ref:https://books.google.com/books?hl=en&lr=&id=PI0cnUDO38QC&oi=fnd&pg=PA87&dq=portman+non-human+primates&ots=QrEFOS7wa8&sig=XXRYsuxxyJ3Aqlrm4HuVbbqQ5Gs#v=onepage&q=portman%20non-human%20primates&f=false
 * King GJ (1978) PMID 208595 did not assess vitamin C consumption by primates, but in an article on other nutrients, expressed an opinion that in the absence of true knowledge of nutrient requirements, diets for captive primates may be over-supplements with micronutrients. David notMD (talk) 15:24, 22 March 2020 (UTC)
 * Thanks for searching. Hopefully someone can locate the governmental zoo regulations for the U.S., Europe, etc. The rationale seems easy, given that all the other animals are cranking the stuff out in their bodies every moment. Came by to also post the topic below. Randy Kryn (talk) 13:08, 25 March 2020 (UTC)
 * I sent a query to a company that makes monkey chow, asking for vitamin C content (unlike for human foods, animal foods are not required to label nutrient content). No answer yet. Possible they are using Portman as a rationale. David notMD (talk) 16:30, 25 March 2020 (UTC)

Wikidata items and interlanguages links
Please see Talk:Chemistry of ascorbic acid. --Mezze stagioni (talk) 12:57, 9 April 2020 (UTC)

Vitamin C usage during the 2019-20 epidemic
This may be of interest and usable on the page, New York hospitals having good results with administering 1.5 grams of C several times a day (which sounds like normal daily usage to me, well or sick). Randy Kryn (talk) 13:08, 25 March 2020 (UTC)
 * That may be more appropriate to the Research section of Coronavirus disease 2019 until after the results of clinical trials are reported. David notMD (talk) 16:34, 25 March 2020 (UTC)
 * www.clinicaltrials.gov lists two ongoing trials "Lessening Organ Dysfunction With Vitamin C (LOVIT)" and "Vitamin C Infusion for the Treatment of Severe 2019-nCoV Infected Pneumonia" as investigating intravenous vitamin C. These can be found by a search on the disease AND vitamin C. David notMD (talk) 16:45, 25 March 2020 (UTC)
 * Note that the newspaper article and the two clinical trial descriptions are about INTRAVENOUS vitamin C given to people who are already in intensive care, not as prevention for people not yet infected, nor for people mildly ill. Intravenous vitamin C achieves far higher blood concentrations than is possible by any amount orally. David notMD (talk) 17:44, 25 March 2020 (UTC)
 * There are some papers/studies current being tried with IV vitamin C as a treatment for sepsis - which occurs as a comorbidity in severe Sars2-Cov-19 but also in many other conditions. The difficult part right now is separating the two - the Chinese are attempting this (perhaps as a last resort?) in these patients. I believe there is an American pulmonoligist doing the same in NY right now although I'm personally skeptical of his results in the absence of any blinding. 81.97.100.208 (talk) 14:11, 26 March 2020 (UTC)

PMID 26808119 (page 51) shows that as oral intake increases to 2500 mg/day, a plateau is reached around 200 mg/day. (No i.v. data in this article.) Elsewhere in the article, makes a point that the known physiological functions of vitamin C require a much lower concentration that is reached with diet intake in the RDA range. My opinion is that oral intake, regardless of amount, will not achieve the circulating and tissue concentrations that MIGHT have an effect on COVID-19. David notMD (talk) 19:51, 26 March 2020 (UTC)

Given that vitamin C has become part of rumor-world for COVID-19, I am going to put a short statement into the vitamin C article. David notMD (talk) 21:02, 26 March 2020 (UTC)
 * Here is what I added. Removed by an editor as original research: "There are ongoing clinical trials of intravenous vitamin C for people who are severely ill with COVID-19. There is no published evidence yet that oral vitamin C has any preventive or treatment effect. As of 26 March 2020 the clinical trials registry clinicaltrials.gov does not list any clinical trials for oral vitamin C. Intravenous vitamin C achieves a much higher plasma concentration than is possible with any amount of oral vitamin C. " QUESTION: If only the first sentence is used, is this no longer original research? David notMD (talk) 07:49, 27 March 2020 (UTC)


 * This kind of thing fuels the rumours. We should stick to policy closely and only cover topics when there are strong secondary sources to hand. Something directly about Vit-C quackery and CV would be great. Alexbrn (talk) 08:34, 27 March 2020 (UTC)
 * In the U.S. there has been a large increase in the purchase of over-the-counter (non-prescription) vitamin C, and also of all other dietary supplements that have ever had claims made for improving the immune system or reducing risk of virus infections or reducing severity and/or duration (examples: Airborne, zinc, echinacea). See NY Times article for information this is all untested for COVID-19. https://www.nytimes.com/2020/03/23/well/live/coronavirus-supplements-herbs-vitamins-colds-flu.html. David notMD (talk) 09:13, 27 March 2020 (UTC)
 * Naturopaths (e.g.) push vitamin injections. So we shouldn't be waving trials around which to the lay public suggest there's something exciting being discovered. Alexbrn (talk) 09:22, 27 March 2020 (UTC)
 * Good point. In time, these and other trials will be completed, and vitamin C will either enter the pantheon of COVID-19 treatments or not. David notMD (talk) 10:07, 27 March 2020 (UTC)

Intravenous vitamin C now has a short mention at COVID-19 drug repurposing research. Only the fact that there are ongoing clinical trials, nothing about plasma concentration or any prior published trials of intravenous vitamin C for sepsis or other serious illness. David notMD (talk) 12:05, 13 April 2020 (UTC)
 * Hopefully this article won't get so bad as that disaster area. Alexbrn (talk) 12:49, 13 April 2020 (UTC)
 * Interesting that for COVID-19, the drug development and drug repurposing articles get fewer views than the vaccine article. And yes, all three articles have too many editors wanting to be the first to add one more thing. David notMD (talk) 14:29, 13 April 2020 (UTC)

Ascorbic Acid (Vitamin C) is part of Front Line Covid-19 Critical Care Alliance's the MATH+ protocol to treat COVID-19. See https://covid19criticalcare.com/wp-content/uploads/2020/06/FLCCC_Alliance-MATHplus_Protocol-2020-6-16.pdf — Preceding unsigned comment added by Tvaughan1 (talk • contribs) 23:47, 19 July 2020 (UTC)
 * I am still of opinion that no mention warranted in article until clinical trial results published. David notMD (talk) 10:17, 20 July 2020 (UTC)

The Code of Federal Regulation 21CFR182.3013 should be referenced in this article.
Pursuant to Code of Federal Regulation 21CFR182.3013, Subpart D, ascorbic acid is defined as a "chemical preservative." DextroseIsCornSugar (talk) 16:05, 24 August 2020 (UTC)

G6PD and Vitamin C
I would like to see mention of large dose vitamin C and its affect on those with a glucose 6 Phosphate dehydrogenase deficiency also known as favism. There are instances of death as the result of large dose vitamin C IV. An individual should be aware if they are deficient before self treating with large dose vitamin C. G6PD deficiency though considered rare is not so rare in some Mediterranean countries and Sub-Saharan Africa. 65.173.109.41 (talk) 02:54, 8 February 2021 (UTC)
 * The Glucose-6-phosphate dehydrogenase deficiency article mentions and has two references connecting intravenous vitamin C mega-dosing to adverse effect, as does the Vitamin C megadosage article. Are there better and more recent lit than what is there? Any mention of same problem with oral mega-dosing? David notMD (talk) 03:17, 8 February 2021 (UTC)
 * Here is a systematic review of supplements in G6PD deficiency from 2017.  This includes vitamin C, and compares the reports of adverse effects of large doses with the safety of therapeutic doses. Jrfw51 (talk) 22:07, 8 February 2021 (UTC)

Dispute over need for a reference
On 9 April 2021 a sentence was added by User:Magnovvig to the Food additives subsection: "It may be used as a flour treatment agent used in breadmaking." Two references were included. My opinion is that the second, from the Federation of Bakers, is sufficient, and that the first, a link to an article in the Independent titled "THE SHOCKING TRUTH" that is a lengthy screed against all bread ingredients not organic, containing a short mention about vitamin C being an ingredient, is not needed. I deleted the first reference. Magnovvig restored it. I hold by my opinion that the Independent ref is not needed to support the very simple factual sentence that is supported by the other reference. I would appreciate hearing from others on this dispute. David notMD (talk) 21:04, 11 April 2021 (UTC)
 * Agree. The first reference is not needed: the second is sufficient. Jrfw51 (talk) 21:16, 11 April 2021 (UTC)
 * I had notified Magnovvig on 9 April. No reply. Deleted the ref again on 13 April. David notMD (talk) 15:45, 13 April 2021 (UTC)

Citations needed
Cleared some citations needed. One remains in first paragraph of Chemistry. David notMD (talk) 06:23, 16 April 2021 (UTC)

Historical anecdote about scurvy in Richard Dana's Two Years Before the Mast
There is a great historical anecdote about scurvy in Richard Dana's Two Years Before the Mast, i.e. https://en.wikipedia.org/wiki/Two_Years_Before_the_Mast, where the author recounts a crew member falling sick and the symptoms--poking his arms made an indentation in the flesh, which did not spring back, as it had lost its elasticity. The brig hails another ship seeking provisions, fresh potatoes and onions. The sick crew member made a mush out of the onions and rubbed it on his gums. He was up in the shrouds within a couple hours. Might be a good addition. FYI. Cheers.
 * Feels a bit too obscure. Scurvy at sea is covered in the article in context of Lind's research, circa 1753. Dana's book is circa 1840. David notMD (talk) 01:08, 17 May 2021 (UTC)

Mistake in scheme describing ascorbate synthesis is mammals.
I removed the picture illustrating the synthesis of Ascorbic acid in mammals for the moment. (https://upload.wikimedia.org/wikipedia/commons/3/35/Vitamin_C_Biosynthesis_in_Vertebrates.svg)

As the article and the sources of that section state correctly the synthesis goes via Gulonate, not Gluconate, as the image showed. Unfortunately I do not have a correct scheme at hand at the moment. — Preceding unsigned comment added by Alpha ScorpiiA (talk • contribs) 17:36, 15 November 2021 (UTC)

water soluble or fat soluble?
I can to the page looking to find out if this is one of the water soluble vitamins or one of the fat soluble ones. I would have thought that's a fairly basic and commonly needed piece of information since it affects how you take the in and how you should consume supliments. I couldn't find the information I was looking for, instead I got bogged down and confused by much more complicated chemistry. 209.93.48.118 (talk) 10:18, 29 January 2022 (UTC)
 * "water-soluble" added to first sentenc of LEad. It was buried way down in the article. David notMD (talk) 11:53, 29 January 2022 (UTC)

Treatment for exercise-induced bronchoconstriction
A meta-analysis shows positive results for using vitamin C to treat exercise-induced asthma. However, if I were to interpret this study in the way some editors would prefer, the only statement this study could possibly back up is "there is no good evidence of vitamin C for treating exercise-induced asthma", given the wording in the conclusion. What statement, if any, could we add to this article based on the study? MarshallKe (talk) 21:18, 13 March 2022 (UTC)

Considering User:Zefr's removal of the section from Exercise-induced bronchoconstriction that was based on this source, I am inclined to add a statement to Vitamin C stating There is insufficient clinical evidence to support vitamin C as a treatment for exercise-induced asthma. MarshallKe (talk) 23:14, 13 March 2022 (UTC)
 * I just finished reading the Hemila-authored meta-analysis three times. I am concerned that what it covers is three small clinical trials (I believe total n=40) and it appears to squeeze the statistical analysis exceptionally hard to justify a lukewarm conclusion. The percentage reduction was modest; the larger relative effect estimate is in my opinion misleading. I also refer you to "Vitamins C and E for asthma and exercise‐induced bronchoconstriction" (PMID 23936673) with a conclusion not as positive as Hemila. Until there is more research on this topic, I suggest making no statement is best. David notMD (talk) 00:22, 14 March 2022 (UTC)

Cancer
removed content and refs about high dose vitamin C and cancer from the Cancer subsection, but left a small amount of referenced content there on a 2015 review which concluded no benefit. There is also mention of high dose vitamin C and cancer in the History section, which remains. The first action was presumably taken because what was removed was early evidence from treatment success, later discredited by reviews that incorporated larger and more rigorously conducted clinical trials. A PubMed search conducted on 8 May 2022, limited to meta-analyses and systematic reviews, did not identify any reviews on intravenous ascorbic acid as cancer treatment that were more recent than the cited Jacobs 2015. Rather than edit warring in the article, I suggest future discussions first take place here. David notMD (talk) 11:55, 8 May 2022 (UTC)

Topical
Somewhat weak journal literature, but topical vitamin C widely marketed as a treatment for melasma and skin aging, especially strong marketing in Japan and South Korea as a dark spot lightening agent. Topical depigmenting and anti-aging products are often referred to as a 'serum.' This usage is not an existing article, hence not present on the Serum disambiguation page. David notMD (talk) 10:12, 14 October 2022 (UTC)

Other diseases - Covid
Umm, quackery...? Just a sprinkle of research on efficacy in Covid and lowering the mortality:


 * https://www.frontiersin.org/articles/10.3389/fimmu.2021.674681/full
 * https://www.aging-us.com/article/202557/text
 * https://annalsofintensivecare.springeropen.com/articles/10.1186/s13613-020-00792-3

This article needs some serious updating.
 * REPLY: Wikipedia guidelines do not accept individual clinical trials as evidence. See WP:MEDRS. Any content about treating (or preventing) COVID requires review refs, preferably meta-analysis. The three hyperlinks provided above are to three trials, one oral, two IV, with mixed results. In my opinion it is premature to make any mention of COVID in the article. See Vitamin D as an example of more evidence and heated dispute. David notMD (talk) 11:23, 12 November 2021 (UTC)
 * MORE: Supplementation with micronutrients, including vitamin C, has been suggested as part of the supportive management of COVID-19, as levels of vitamin C in serum and leukocytes are depleted in the acute stage of infection owing to increased metabolic demands. The use of high-dose intravenous vitamin C has been studied.  According to ClinicalTrials.gov, there are 50 completed or ongoing clinical trials including vitamin C, which have completed or are recruiting people, hospitalized and severely ill with COVID‑19.


 * There is a much more recent meta-analysis of RCT of Vitamin C in Covid-19 which should be included. This meets WP:MEDRS standards.  Overall results are negative. Jrfw51 (talk) 17:14, 12 November 2021 (UTC)
 * Content added to article, using the Rawat reference. David notMD (talk) 11:49, 13 November 2021 (UTC)

Can we mention the Vitamin C treatment protocol used in hospitals during the C-19 pandemic? (Also, perhaps in the "History" (Large Doses) section.) (Rather than the C-19 section.) Drsruli (talk) 20:32, 6 May 2022 (UTC)

Of course, all megadosing is contentious. That's why I suggested that it (maybe) be put in the history section, similar to what was done for cancer therapy. (It's history, it happenned, it can be documented.) (I didn't mean to describe the protocol itself, but the event.) Drsruli (talk) 21:09, 7 May 2022 (UTC)
 * Across all the vitamin articles, History as a section is limited to identifying the vitamin as essential to life, not about any use of higher amount in people who are not vitamin deficient, as a therapy for specific diseases. Vitamin C is an exception because of Pauling, but the content is limited to the applications Pauling promoted: common cold and cancer. David notMD (talk) 11:40, 8 May 2022 (UTC)

Is Vitamin C and C-19 more contentious than Vitamin C and cancer? (In that case, then just mention it in the Other Diseases section. Along the lines of how it was included in History.) (Could also say that the C-19 use is relevant to Pauling because, coronaviruses.) [You just made me smile; "If Pauling were alive today..."]Drsruli (talk) 01:31, 9 May 2022 (UTC)

COVID revisted
See article and below for mention that meta-analyses of clin trials for COVID treatment with vitamin C (mostly intravenous for severe cases) now incorporated as an article update. David notMD (talk) 09:40, 21 December 2023 (UTC)

Primate requirements
Did you ever find and add the amount of ascorbic acid required by law to be given to apes and monkeys in zoos, labs, etc.? In the 1990s this was, if I recall correctly and as we discussed previously, about the equivalent of 3,600 mgs in relationship to the average human. This is information which should be in the article, especially if you are going for feature status. Thanks. Randy Kryn (talk) 15:07, 24 December 2023 (UTC)
 * I will add that to my VERY long to-do list. (Interesting, by the way, that what I brought to Good Article back in 2017 so clearly has massive room for improvement. And not just because there are new journal articles to incorporate.) David notMD (talk) 16:42, 24 December 2023 (UTC)
 * Thanks, it seems an important component of suggested usage. Nice work, and Merry Christmas. Randy Kryn (talk) 16:55, 24 December 2023 (UTC)
 * I found two sources that I believe can be references, which both state that vitamin C at 3-6 mg/kg body weight is sufficient to maintain plasma levels and prevent scurvy. One said 3 mg/kg for adults, 6 mg/kg for young. This is roughly 3-4X the recommended intake for adult humans expressed as mg/kg body weight. In contrast, 3,600 mg is roughly 50X what is recommended for humans. David notMD (talk) 17:43, 24 December 2023 (UTC)
 * I added text and a ref to last paragraph of the Animal synthesis section. David notMD (talk) 21:57, 24 December 2023 (UTC)
 * Which is why the legally required amount for captive apes would be an important measurement, and if that legally required amount has changed over the years. Yes, a small amount will prevent scurvy, which is the bare minimum that primates need to live. Thanks for your research. Randy Kryn (talk) 01:28, 25 December 2023 (UTC)
 * This 1990 article may be useful. Randy Kryn (talk) 01:53, 25 December 2023 (UTC)
 * That ref says that nonhuman primates require 2 mg/kg, and that a recommended diet should deliver 10 mg/kg. Those numbers are in same order of magnitude as the 3-6 mg/kg I found mentioned in the Merck veterinary manual. Neither source makes any mention of a "legally required amount". David notMD (talk) 08:38, 25 December 2023 (UTC)
 * Not too different from the 1-2 mg/kg body weight recommended for humans (see Diet section of the article). David notMD (talk) 11:54, 27 December 2023 (UTC)

Checking for newer meta-analyses and systematic reviews
Checking for relevant meta-analyses and systematic reviews published after this became a Good Article in late 2017. David notMD (talk) 04:18, 18 December 2023 (UTC)
 * Removed some of the Common cold subsection text and references and added a 2023 meta-analysis. David notMD (talk) 21:23, 18 December 2023 (UTC)
 * COVID-19 subsection replaced because of new references. David notMD (talk) 16:07, 18 December 2023 (UTC)
 * Added Type 2 diabetes subsection based on 2023 meta-analysis. David notMD (talk) 21:19, 18 December 2023 (UTC)
 * In process of adding Adverse effects for high dose intravenous administration, also Pharmacodynamics and Pharmacokinetics for high dose intravenous. David notMD (talk) 12:43, 22 December 2023 (UTC)
 * Added blood pressure subsection based on two meta-analyses. Did not add text and ref (one meta-analysis) about intravenous VitC for burns treatment, as results were deemed inconclusive by authors. David notMD (talk) 12:01, 23 December 2023 (UTC)
 * Replaced Food fortification. David notMD (talk) 00:44, 4 January 2024 (UTC)
 * Added Sepsis subsection under Medical. David notMD (talk) 16:32, 5 February 2024 (UTC)

Ref fixes
A FA reviewer recommended consistency in reference page numbering and sentence versus title case in article titles. Addressing this is resulting in a large number of Edit summaries as ref fix (minor). David notMD (talk) 13:07, 13 February 2024 (UTC)
 * Completed. David notMD (talk) 14:16, 20 February 2024 (UTC)