Talk:Vitamin C/GA2

GA Review

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I'll take this on. Reviewer: Chiswick Chap (talk · contribs) 18:48, 17 November 2017 (UTC)

Summary

This has been a detailed GA review. The article is now well up to the required standard and is a worthy biology GA. Chiswick Chap (talk) 13:44, 27 November 2017 (UTC)

Comments

Extended content

• It is mentioned that Vit. C cures scurvy long before scurvy is discussed and explained under Deficiency.

Text of first paragraph of Lead changed. Same reference applies. David notMD (talk) 20:02, 17 November 2017 (UTC)

The issue is the Scurvy section, which precedes the Deficiency#Scurvy discussion.

 Done Scurvy section in Medical uses expanded. David notMD (talk) 01:04, 18 November 2017 (UTC)

• The table of US Vitamin C recommendations repeats "Recommended Dietary Allowance". Perhaps add (RDA) to the text where it's wikilinked and then use RDA in the table.

 Done David notMD (talk) 20:02, 17 November 2017 (UTC) Also added RDAs for children David notMD (talk) 20:02, 17 November 2017 (UTC)

• In Biological significance, it is claimed that vit. C is "a highly effective antioxidant, acting to lessen oxidative stress;". This is either uncited altogether, or cited to the Linus Pauling institute, not necessarily a reliable source on this matter (given the history). The vitamin is certainly an antioxidant in vitro, but its action in vivo is open to doubt. Better explain what is meant a bit more fully, and provide WP:MEDRS evidence for the claim.

Linus Pauling Institute is affiliated with Oregon State University, and is considered (mostly) credible on nutrition topics. However, I will look at all of the text that has LPI as a citation (#46) to see if any can be replaced by sources more likely to be perceived as NPOV. David notMD (talk) 14:47, 18 November 2017 (UTC)

The current-day LPI shouldn't be discredited for the eccentric views of its namesake, as it is a world-class nutrition center staffed with high-quality faculty holding US national and international competitive grants. In my opinion, 1) the LPI article on vitamin C is one of the most comprehensive and updated (2014) reviews available; and 2) further, it is written for the lay public, making it suitable and digestible for WP users. However, we should use an origin source for how the DRI was established, current ref #9 (published in 2000), or the Institute of Medicine online book review here (both are bulky to read, but this is a little easier to navigate than ref #9, imo) which defines an in vivo antioxidant as best as available, as well as providing much more information than we can reasonably include for the encyclopedia. --Zefr (talk) 17:52, 18 November 2017 (UTC)

Many thanks, that was very useful. Just what we needed to know. Chiswick Chap (talk) 18:42, 18 November 2017 (UTC)

• Either under Common cold, or under History (or even both, briefly), please mention Linus Pauling and his (bizarre) advocacy of the vitamin, and subsequent debunking. BTW since his photo is on Commons, consider including it.

Added content to Common cold section, including how LP fit in. Will add more detail to History. The description of the Hemila 2013 meta-analysis was in error - I changed that.

The history of Pauling's involvement in vitamin C megadosage added as a subsection in Discovery. David notMD (talk) 18:53, 25 November 2017 (UTC)

• The last 2 sentences of the Pauling paragraph are uncited.

 Done Citation added for Pauling's book. Last sentence deleted, as it was original research. David notMD (talk) 02:01, 21 November 2017 (UTC)

• The "biosynthesis route" at the end of Biosynthesis is inadequately formatted and explained (and looks excessively technical), and might be better either as a table with explanations, as a diagram, or in a properly glossed paragraph of text.

As in not done yet. What I intend to do here is replace the biological route with a narrative paragraph, after moving the existing content to here in Talk, so that if any editor wants to consider rescuing it, it will be here. The narrative paragraph will include naming the enzymes involved in the process, and add that depending on species, takes place in liver or kidneys. What I really wanted was a diagram. For industrial synthesis there is a good diagram of the Reichstein process, but there is no equivalent diagram in the Commons of the biological synthesis pathway. David notMD (talk) 11:55, 21 November 2017 (UTC)

 Done Replaced biosynthesis route with routes for both animals and plants. With citations. David notMD (talk) 02:24, 22 November 2017 (UTC)

• There are uncited paragraphs and citation needed tags in the Evolution and Absorption sections.

I worked on the Absorption section, but have not been able to find citations for two parts of the content. Currently marked as "Citation needed". I have not looked at the Evolution section yet.David notMD (talk) 11:45, 21 November 2017 (UTC)

The choice is cite or remove.

Removed uncited content from Absorption a while back. Still looking for citable replacement text. David notMD (talk) 18:54, 25 November 2017 (UTC)

• The recommendations, among other things, do stand out as US-centric. What about other regions?

The content would get overly long if recommendations by age and sex were added for several/many countries. There already is a list of recommendations from various countries and agencies, with citations. These are in increasing order to give a sense of range, and by doing so, demonstrate a lack of consensus. There is no means of explaining why countries do not agree (nor is this unique to vitamin C). David notMD (talk) 20:02, 17 November 2017 (UTC)

Nobody has suggested lists, but the US-centricity is not acceptable. The text needs to discuss and provide references to recommendations from, say, Europe and the Far East. The American materials can then serve as examples. you can then say "Recommendations vary somewhat, but for example..." and "Recommendations on X are similar in the USA, Japan, and Australia, but ..." to give a feeling for the variety and differences.

Added more information on the extremes: numbers for India being lower and EU higher than USA and Canada. David notMD (talk) 01:04, 18 November 2017 (UTC)

It's certainly an improvement, but the last 3 paragraphs of the section still run "The U.S.", "of the U.S.", "For U.S.", so I don't feel we're quite balanced yet.

 Done Added non-US to second and third of those paragraphs; third now in sub-section "Food labeling." Not finding equivalent national survey information to the U.S. NHANES and WWEIA David notMD (talk) 17:51, 19 November 2017 (UTC)

• The lists of sources of the vitamin are tending towards excessive (WP:UNDUE), not least because numerous plant sources have very similar values (indeed, a whole lot are exactly 30 mg/100g). All that is needed for the article is a few examples to show the range: these could be presented as a brief list with say 10 rows shown, or in text. The detailed lists could be hived off to a list article, though since Wikipedia is not a how-to-eat guide, they are arguably surplus to requirement.

Started. David notMD (talk) 20:02, 17 November 2017 (UTC)

Table shortened from 74 to 53 foods. I am loath to shorten it much more because foodies want to see commonly consumed foods (and also to see those exotics at the top of the list. David notMD (talk) 01:21, 18 November 2017 (UTC)

It's very slightly better. I suggest we merge entries for, say, fruits which share values, e.g. Elderberry, Cloudberry, Papaya, Strawberry: 60; Grapefruit, Lime, Passion fruit, Mango, Blackberry, Raspberry: 30; Blueberry, Grape, etc: 10; similarly for vegetables e.g. Spinach, Cabbage: 30; etc. This will reduce the number of rows without throwing anything away. The extensive table still looks as if we're trying to be a directory and complete database, which is definitely not our mission.

• The stand-alone word "Source:[123]" at the end of the plant sources section is a bit odd. Suggest put the ref at the end of the sentence introducing the tables.

 Done Put into table header. David notMD (talk) 20:02, 17 November 2017 (UTC)

• There are citation needed tags in the History, and it is doubtful if the uncited claims are even correct. "Lime" may have denoted the lemon, which may have been known at the time as a citron, for example. Perhaps this would be worth fact-checking.

• "The overwhelming majority of species of animals (but not humans, guinea pigs or fruit bats) and plants synthesize their own vitamin C." Since the source only discusses vertebrates, the claim is unjustified. Suggest we also remove the italics, and say "The majority of vertebrates, but not humans, guinea pigs or fruit bats, synthesize their own vitamin C." Plants aren't relevant here either.

 Done Also revised following text, as writing was muddled ("reliable" not appropriate). David notMD (talk) 14:47, 18 November 2017 (UTC)

• Supplements says "available" three times, which is at least twice too many. I'm unsure why we're listing the formats in which it's sold as this is probably straying into WP:NOTDIR and WP:UNDUE territory. The section is also very weakly cited: I couldn't find "drink" or "capsule" in the Pauling Institute source, for instance, so I think it needs to be rewritten (start over) from fresh sources.

Shortened, and removed mentions of specific products. Will come back to this with appropriate citation(s). David notMD (talk) 14:47, 18 November 2017 (UTC)

 Done Citations added. However, Davis (for liposomes) is a primary citation. There are no secondary citations in the literature. For ascorbyl palmitate, there is a Wikilink, but no useful literature. The alternative here is to delete mention of both. In addition, there is a marketing confusion I am avoiding, in that there are products called either Vitamin C Ester or Ester-C that are not esterified, e.g., having a fatty acid attached, but instead contain calcium ascorbate, with claims for less distressing to the stomach compared to ascorbic acid. The evidence for this is one clinical trial that used a dose of 1000 mg, which is much larger than the recommended amounts on the order of 100 mg. [Gruenwald J, Graubaum HJ, Busch R, Bentley C. Safety and tolerance of ester-C compared with regular ascorbic acid. Adv Ther. 2006 Jan-Feb;23(1):171-8. PubMed PMID: 16644619] David notMD (talk) 14:15, 19 November 2017 (UTC)

• First recorded controlled experiment: What about Nero's experiment on digestion and exercise then? He fed a banquet to two slaves, had one rest and the other exercise, then looked at their stomach contents. Small sample, unethical, but definitely a control.

 Done Removed sentence. No citation found that makes this claim. The same claim is in the Wikipedia article on James Lind, but not referenced there either. David notMD (talk) 15:01, 18 November 2017 (UTC)

Oh, I meant it was an early controlled trial, just not the very first one. There are plenty of sources for that. Further, the source confirms the urban story, that Lind used lemons not limes, and that lemons worked well where limes didn't when they were accidentally substituted some years later - this is relevant and does seem worth mentioning. I've added the ref for you.

Nice find on Baron 2009. I am not comfortable with the vitamin C content table for animal-sourced foods, mostly because some are listed raw and it is known that vitamin C is destroyed by heat. I am going to go to the USDA tables to see if different values are given for raw and cooked. If the latter is as low as I anticipate, I will do away with the table entirely and condense to text. P.S. Don't know if you saw this, but I have a declared COI in the vitamin C Talk and my own Talk, in that my day job is science consultant to dietary supplement companies, advising on health claims. None of my clients are aware that I am a Wikipedia editor. David notMD (talk) 17:23, 18 November 2017 (UTC)

OK, I'll wait for it. No problem with the declared COI, hope it's no trouble to you "IRL".

Removed the animal-sourced table, as according to most recent USDA database (referenced), cooked meat contains negligible amounts of vitamin C. Not sure how long ago this table was created, but putting entries for raw liver into it was misleading. David notMD (talk) 01:38, 19 November 2017 (UTC)

• Better give the etymology someplace - could be the history (ascorbic = anti-scorbutic factor = scurvy preventer).

From Latin, a- means away from or off; scorbic also Latin from scorbutus/scorbuticus for scurvy. So yes, a prevention/cure for scurvy. The Discovery section already has this sentence pegged to 1933: "Haworth and Szent-Györgyi now proposed that the substance L-hexuronic acid be called a-scorbic acid, and chemically L-ascorbic acid, in honor of its activity against scurvy." I will add a sentence about the Latin roots once comfortable with a citation (probably OED). David notMD (talk) 19:52, 19 November 2017 (UTC)

 Done Added sentence and citation to an entymology dictionary. David notMD (talk) 00:47, 20 November 2017 (UTC)

I've tidied it up and cited the ref properly for you.

• We'd better think about a logical order for the sections. Right now the first words in the body of the article are "A 2012 Cochrane review found no effect of vitamin C supplementation on overall mortality." and that's the whole of the first paragraph: obviously something's well adrift here. There are some options. A traditional way to begin is with the history and etymology. Since it's a chemical substance, we could logically begin with the chemistry. Or, we could take the view it's an important aspect of biology and start with "Biological significance". Unless you have strong objections, I'd suggest Chemistry; Biological Significance; Medicine (subsections Uses, Side effects); Diet (subsections Sources; Recommendations); History; Society and culture. Oh, and you'd better sort out that one-sentence paragraph.

Added a short introductory text to "In medicine" and moved that bald sentence to the end, with its own section sub-title. I want to have some thinking time before addressing order of sections. I looked at the other vitamins and there does not appear to be a consistent format (none of them are GAs). P.S. Removed my two New Sections from Talk before anyone else started commenting on them. David notMD (talk) 14:02, 20 November 2017 (UTC)

OK. Yes, if other stuff is in a muddle then it's not much of a guide. Suggest we go with logic.

I think "Biological significance" should follow the lede, although the topics under that subhead need editing. The current subtopics: 3.1 Deficiency 3.2 Testing for levels 3.3 Biosynthesis 3.4 Evolution 3.5 Absorption, transport, and excretion 3.6 Enzymatic cofactor 3.7 Immune system 3.8 Role in plants where the struck topics are more logical elsewhere. Overall, I recommend a general order somewhat similar as used by LPI:

1. Function (current Biological significance section)
2. Bioavailability (current Biological significance section; to include Chemistry)
3. Deficiency and RDA/DRI (to include Testing)
4. Food sources and supplements (current In the diet section)
5. Disease prevention (current In medicine section)
6. Disease treatment (combine with In medicine)
7. Safety
8. Industrial synthesis
9. History and evolution (trim: the history and discovery sections are too extensive; WP:NOTEVERYTHING)
10. Role in plants
11. Society and culture

--Zefr (talk) 16:50, 20 November 2017 (UTC)

Partially agree. I think we should keep the medical section together, also the biological section: these are clearly coherent. And I don't agree at all with putting history and evolution together, these are two incommensurable timescales, one in centuries, one in geological time.

On the length of the history and discovery sections, I think they're not unreasonable given the length of the article (122k), though the discovery could indeed be copy-edited down a bit. We could hive them off and summarize, but I don't feel it's necessary. Chiswick Chap (talk) 16:52, 20 November 2017 (UTC)

This article definitely a moving target now as far as addressing some of the bullets we started with on Friday! I like Biological significance before In medicine, and Diet to include recommendations and food sources. I agree with keeping separate Evolution and History. To the latter I intend to add a subsection on Vitamin C megadosage, to incorporate the flurry of research that Linus Pauling sparked, without name-calling, while at same time making clear that the evidence to date does not support the theories of super high vitamin intake as having any benefits. That should complete the LP bullet. I also intend to collapse the Side effects subsection, using the DRI and LPI citations to support what the ill effects are. David notMD (talk) 18:23, 20 November 2017 (UTC)

OK, though the bullets remain pretty much 100% relevant (and nearly all completed, actually). Pauling indeed needs expansion. Chiswick Chap (talk) 18:59, 20 November 2017 (UTC)

• Lead section needs reorg and extension to reflect the body of the article, and to mention industrial synthesis, chemistry, and history (i.e. all sections). Chiswick Chap (talk) 19:03, 20 November 2017 (UTC)

Keeping track of bulleted comments outstanding. I condensed the Side effects content. David notMD (talk) 20:42, 20 November 2017 (UTC)

Completely rewrote Lead to reflect change in order of sections and of section titles. David notMD (talk) 23:20, 20 November 2017 (UTC)

Lead needs to summarize Biology section.

Completely rewrote Lead (again) to reflect major changes in content and order. Three paragraphs. With citations, as this style jibes with all the other vitamins. David notMD (talk) 12:57, 27 November 2017 (UTC)

• Food fortification should be under Diet not Society and culture.

 Done David notMD (talk) 22:21, 20 November 2017 (UTC)

* The 'Compendial status' seems a bit of an inflated heading and not terribly cultural. Perhaps we can lose it and instead mention the pharmacopoeias somewhere under Medicine? Chiswick Chap (talk) 09:15, 21 November 2017 (UTC)

I left the content at the end, but under a separate section title "See also"

Not ideal really, are we to See also these items from every additive and drug? I suggest we either cut them out or use them in the text with citation. Chiswick Chap (talk) 13:17, 21 November 2017 (UTC)

I see that you left them, but for the moment made invisible in the article. I looked at them, and agree with cut entirely. Both documents are LONG lists of items that are in the Pharmacopoeias. Not informative. David notMD (talk) 13:26, 21 November 2017 (UTC)

• Page numbers should be like 123–129, not 123–9 or 123–29. There are several.

Actually, there are several score. Some of the popular citation makers truncate page numbers automatically. I will work through these. David notMD (talk) 14:37, 21 November 2017 (UTC)

 Done Page numbering now consistent for all citations. David notMD (talk) 02:31, 26 November 2017 (UTC)

• I can't see any logic to having "Biological significance" outside the Biology section. Suggest we merge them: and if we want the significance bit at the top, that means putting the whole section at the top, with significance first. Chiswick Chap (talk) 09:20, 22 November 2017 (UTC)

• Not convinced we need such extensive quotations on cancer, especially as they just add up to a simple message. That section is also growing rather large for the article - much more and we'd need to split it out and summarize it briefly here with a {{Main|Vitamin C for cancer}} link. Suggest just paraphrase the quotations for now, and copyedit a little for length if possible. Chiswick Chap (talk) 11:21, 25 November 2017 (UTC)

Shortened text in the IV cancer paragraph. I would prefer to keep the remaining quotes in attempt to be NPOV on this controversial topic. Clinicaltrial.gov lists 32 (!) trials in various stages, so what we have should serve as a placeholder for the future. David notMD (talk) 19:09, 25 November 2017 (UTC)

Thanks. If anyone does want to add 32 trials then it will be in a separate article. Chiswick Chap (talk) 19:33, 25 November 2017 (UTC)

• The sections on RA, Dementia and Cataract are all very short, more glaringly so in comparison to the Cancer section. It would be best to merge these into one section ('Other conditions'). Yes, I know. Chiswick Chap (talk) 19:36, 25 November 2017 (UTC)

 Done

Summary of biology in the lead

Extended content

For a summary of the biology in the lead we state "Vitamin C is an essential nutrient involved in the repair of tissue.[1]<"

The biology of a substance is often fairly complicated. Not sure how much more we need in the lead than this.

References

Have also restored the references to the lead and adjusted the layout of the article. Doc James (talk · contribs · email) 17:16, 21 November 2017 (UTC)

The lead should reflect the article's contents. The lead should briefly mention the biosynthesis (if only to say there are various pathways) and the vitamin's evolution, at least. Chiswick Chap (talk) 17:23, 21 November 2017 (UTC)

Other thoughts to include in the lead. The LPI review and EFSA panel of multiple experts add to vitamin C functions with sufficient evidence as:

• synthesis of collagen and catecholamines
• immune system
• in vivo antioxidant
• "protection of DNA, proteins and lipids from oxidative damage, normal collagen formation, normal function of the nervous system, normal function of the immune system, maintenance of normal function of the immune system during and after extreme physical exercise, non-haem iron absorption, and normal energy-yielding metabolism" (EFSA 2009)
• FDA states vitamin C among vitamins A-C-E as the only dietary compounds with sufficient evidence for in vivo antioxidant activity to be mentioned on product labels as antioxidants (because they have defined RDIs, whereas many supplement and food product ingredients do not). --Zefr (talk) 17:59, 21 November 2017 (UTC)

Indeed, the biology has been around for millions of years, the medicine for 100, so a little more emphasis on it in the lead of this biology article would be welcome. Chiswick Chap (talk) 18:04, 21 November 2017 (UTC)

Yes it is an antioxidant. But that something is an antioxidant is often used to promote its use as a supplement and it is more important IMO that there is very little evidence for supplementation among most people. Oxidation is a key mechanism that ones body uses to deal with cancer which is why vitamin E may increase the risk of cancer among smokers. No evidence that this is a concern with vit C but more that antioxidant does not equal good. Doc James (talk · contribs · email) 07:31, 23 November 2017 (UTC)

Indeed, we agree on that. Chiswick Chap (talk) 07:34, 23 November 2017 (UTC)

Stepping away from this now (Tuesday afternoon), back on Saturday morning. I am deeply unhappy with the Lead as it now reads, which is a complete revert to before the Good Article nomination started. The order of sections appears to be in flux. I hope that settles down by Saturday. If it has, I will provide a revised lead to parallel the order and content of the sections in the article. At that time we can decide whether Leads for vitamins have citations or not. If we are to consider uniformity, all of the other vitamins have citations in the Lead. David notMD (talk) 18:54, 21 November 2017 (UTC)

I doubt much will now change, and we agree the lead has mistakenly been reverted. Although this is a biology article I suggest we just accept having citations sprinkled about. Chiswick Chap (talk) 18:58, 21 November 2017 (UTC)

Have added this bit back to the lead with references "There is, however, is some evidence that regular use may shorten the length of colds.[1] It is unclear if vitamin C supplementation affects the risk of cancer, heart disease, or dementia.[2]" Doc James (talk · contribs · email) 07:59, 23 November 2017 (UTC)

Er, that would be fine except for the broken sentence structure. I just fixed the redundant "is". Chiswick Chap (talk) 08:04, 23 November 2017 (UTC)

Thanks. Doc James (talk · contribs · email) 08:06, 23 November 2017 (UTC)

It is good practice to have references supporting the text in front of it. This is not "sprinkling" them about. Doc James (talk · contribs · email) 01:49, 26 November 2017 (UTC)

We already agreed to have the lead of this biology article cited as stated below. Chiswick Chap (talk) 08:20, 26 November 2017 (UTC)

Biology

Extended content

We usually put the use of stuff in other animals / species such as plants lower in the article (often in a section called "Other animals" or "Other organisms". Currently we have a section called "role in plants" which IMO is fine. If details on other organisms is expanded to make up a large portion of this article we could split it out as "Vitamin C in other organisms"

IMO the mechanisms of action of a vitamin should not be the first paragraph of the article. The use of a substance IMO is more what a general reader is looking for and can be presented in easier to understand terms and thus should go first. Doc James (talk · contribs · email) 08:03, 23 November 2017 (UTC)

Thank you for your comments, which I will take into consideration. I do agree that having the 'biological significance' without the rest of the biology is not right and I am awaiting nom to correct that: he will be back at the end of the week and I would prefer not to have further instability in the article before then. Chiswick Chap (talk) 08:24, 23 November 2017 (UTC)

We discuss the biological significance in the second sentence of the lead which is scurvy. We could split off "Vitamin C is an essential nutrient involved in the repair of tissue" from the second paragraph and expand it into a paragraph on biology / mechanism but care will need to be taken to make sure we write it in understandable English.

Generally the lead should be no more than 4 paragraphs per WP:LEAD Doc James (talk · contribs · email) 09:23, 23 November 2017 (UTC)

We know. The plan remains to rewrite the lead, with citations, to reflect the whole of the body once the comments on the article body have been closed out. Chiswick Chap (talk) 09:28, 23 November 2017 (UTC)