Talk:Vitamin C

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Good articleVitamin C has been listed as one of the Natural sciences good articles under the good article criteria. If you can improve it further, please do so. If it no longer meets these criteria, you can reassess it.
Did You Know Article milestones
DateProcessResult
December 3, 2004Featured article candidateNot promoted
February 21, 2007Good article nomineeListed
March 24, 2007Peer reviewReviewed
February 26, 2010Good article reassessmentDelisted
November 27, 2017Good article nomineeListed
Did You Know A fact from this article appeared on Wikipedia's Main Page in the "Did you know?" column on January 11, 2018.
The text of the entry was: Did you know that in 1934 vitamin C was the first synthetic vitamin to be trademarked (as Redoxon) and marketed?
Current status: Good article

Evolution section needs some work[edit]

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)

First sentence[edit]

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)

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[edit]

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[edit]

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?[edit]

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.[1]) 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"?[1] 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)

References

  1. ^ Cortés-Jofré, M.; Rueda, JR; Corsini-Muñoz, G.; Fonseca-Cortés, C.; Caraballoso, M.; Bonfill Cosp, X. (17 October 2012). "Drugs for preventing lung cancer in healthy people". Cochrane Database Syst. Rev. doi:10.1002/14651858.CD002141.pub2. PMID 23076895.

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)

Use before mechanism[edit]

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)

@Doc James: 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#Biology. Seppi333 (Insert ) 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). Seppi333 (Insert ) 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)

Pharmacodynamics[edit]

Moot - I answered my initial question; I'll need to find a SCIRS-quality citation before including the enzymes that are missing from Vitamin C#Pharmacodynamics anyway.

@Boghog: 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 GO:0031418 ("L-ascorbic acid binding") describe activity as a cofactor and GO:0016715 (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#Pharmacodynamics. Based upon Cofactor (biochemistry)#Vitamins and derivatives, 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. Seppi333 (Insert ) 13:15, 23 December 2018 (UTC)

Actually, I just noticed GO:0031418 is listed under GO:0050662#display-sentences-tab, 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 GO:0031418? Seppi333 (Insert ) 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. Seppi333 (Insert ) 15:11, 23 December 2018 (UTC)

Entries listed under GO:0031418 for Homo sapiens
Gene/product identifier Full name of gene or gene product mentioned?
ALKBH3 Alpha-ketoglutarate-dependent dioxygenase alkB homolog 3 N/A - not a cofactor (UNIPROT)
DBH Dopamine beta-hydroxylase Y
EGLN1 Egl nine homolog 1 Y
EGLN2 Egl nine homolog 2 Y
EGLN3 Egl nine homolog 3 Y
OGFOD1 Prolyl 3-hydroxylase OGFOD1
OGFOD2 2-oxoglutarate and iron-dependent oxygenase domain-containing protein 2
OGFOD3 2-oxoglutarate and iron-dependent oxygenase domain-containing protein 3
P3H1 Prolyl 3-hydroxylase 1 Y
P3H2 Prolyl 3-hydroxylase 2 Y
P3H3 Prolyl 3-hydroxylase 3 Y
P4HA1 Prolyl 4-hydroxylase subunit alpha-1 Y
P4HA2 Prolyl 4-hydroxylase subunit alpha-2 Y
P4HA3 Prolyl 4-hydroxylase subunit alpha-3 Y
P4HTM Transmembrane prolyl 4-hydroxylase Y
PAM Peptidyl-glycine alpha-amidating monooxygenase Y
PHYH Phytanoyl-CoA dioxygenase, peroxisomal
PLOD1 Procollagen-lysine,2-oxoglutarate 5-dioxygenase 1 Y
PLOD2 Procollagen-lysine,2-oxoglutarate 5-dioxygenase 2 Y
PLOD3 Multifunctional procollagen lysine hydroxylase and glycosyltransferase LH3 Y
Seppi333 (Insert ) 22:55, 28 December 2018 (UTC)

Captive primates and Vitamin C[edit]

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)
Doc James, 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)