Talk:Vitamin B6/GA1

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Reviewer: Esculenta (talk · contribs) 18:49, 3 August 2021 (UTC)[reply]


Hello, I will review this article for its GA-candidacy. I should have comments here within a few days. Esculenta (talk) 18:49, 3 August 2021 (UTC)[reply]

  • the lead is too short and doesn’t do a good job of summarizing the article. See WP:LEAD for guidance.
  • the article needs links all over the place for jargon terms that we shouldn't expect the reader to know. Examples: pyridine, co-factor, fatty acid, chlorophyll, E. coli, 1-deoxyxylulose-5-phosphate, macronutrient, enantiomer, transcription factor, desaturation, formyl, micronutrient, systemic inflammation, liver disease, rheumatoid arthritis, HIV, oral contraceptive, antivitamin, passive diffusion, mucosa, bioavailability
  • some abbreviations like MPM and PLP are used before they are even defined
  • why did György name this B6?
  • "characterization of pyridoxamine, the animated product of pyridoxine" aminated?
  • "Vitamin B6 is found in the germ and aleurone layer of grains, and milling results in the reduction of this vitamin in white flour." this statement needs a citation; a comparison of vitamin amounts to milled flour would be a useful comparison, I think. Or, give typical % decrease after milling.
    • Table now includes whole wheat and white bread, and brown rice and white rice, as examples. David notMD (talk) 10:49, 24 August 2021 (UTC)[reply]
  • it is claimed that fruits other than citrus are "among the richest sources" of B6, but the only example I see in the three-column list is raisins. My copy of Combs says "Milk, eggs and fruits contain relatively low concentrations of the vitamin."
  • there’s a couple of citation needed tags in the "Absorption and excretion" subsection
    • Changed to Absorption, salvage and excretion, and referenced. David notMD (talk) 03:24, 22 August 2021 (UTC)[reply]
  • the "Sources" tables are confusing to me: is the amount given beside the source the amount of one serving? If so, then /serving does not need to be part of the columns heading; if not, then it's not useful to add that in the column header, because we don't know what the serving size is! Also note that column 1 is formatted as "mg serving" while 2 and 3 are "mg/serving".
    • Sources table changed to mg/100g (to be in accord with other vitamin articles).David notMD (talk) 20:13, 18 August 2021 (UTC)[reply]

These items above are easily addressed. However, I think the article has a bigger issue with missing information. I used several sources to help me assess if WIAGA criteria 3 is met (3.Broad in its coverage: (a) it addresses the main aspects of the topic"). This included a more recent edition of the Combs textbook already used in the article, an introductory biochemistry textbook, an introductory nutrition textbook, and a search of review articles from pubmed, published in the last five years (i.e., WP:MEDRS compliant). Based on these sources, here's information I would expect to see in the article:

  • should state that all B6 vitamins are derivatives of the 3-hydroxy-2-methylpyridine structure; a labeled diagram might be helpful readers to visualize the numbered positions on the ring and side chain
  • article should state that pyridoxine or pyridoxol (PN), pyridoxal (PL) and pyridoxamine (PM), have, respectively, alcohol, aldehyde and amine group in the 4-position – i.e., stating clearly the chemical differences between the related vitamers
  • should say that PLP is attached to the apoenzyme by a Schiff base (aldimine) linkage (–N=CH–) formed through condensation of the 4-carbonyl group with the ε-amino group of specific lysine residues. No mention of the biochemistry of PLP binding to protein via its Schiff base, its pH dependence, and how this affects B6 absorption. How does the coenzyme work biochemically?
  • article should state explicitly somewhere that there are 6 vitamers of B6
  • article does not mention yeast extract nor wheat bran as particularly high dietary sources
    • Table not meant to be comprehensive, so supplement-type 'foods' not included. David notMD (talk) 11:20, 22 August 2021 (UTC)[reply]
  • no mention that much of plant-based B6 is in the form of a bound glucoside conjugate 5-O-(β-D-glucopyranosyl)pyridoxine; this is relevant because this plant-based form has a lower bioavailability.
  • no mention of the fact that bacterially synthesized B6 in the large intestine is a potential exogenous source
    • Text and ref added into Sources to address endogenous bacteria contribution of B6. David notMD (talk) 18:01, 20 August 2021 (UTC)[reply]
  • no mention of the vitamin B6 salvage pathway? PMID 30037155
    • Parra 2018 ref and salvage incorporated into Absorption, salvage and excretion. David notMD (talk) 03:24, 22 August 2021 (UTC)[reply]
  • what happens to newly absorbed B6? There’s no mention of the fact that it gets delivered to the liver to get converted to the active form for circulation.
    • Incorporated into Absorption, salvage and excretion. David notMD (talk) 03:24, 22 August 2021 (UTC)[reply]
  • no mention of how newly formed PLP, contained in small, rapid turnover pools – independent of the endogenous coenzyme pools – get released into the bloodstream attached to albumin
    • Incorporated into Absorption, salvage and excretion. David notMD (talk) 03:24, 22 August 2021 (UTC)[reply]
  • what enzyme is responsible for the conversion to 4-pyridoxic acid?
    • Incorporated into Absorption, salvage and excretion. David notMD (talk) 03:24, 22 August 2021 (UTC)[reply]
  • what is the typical total body pool of B6? Where is most of it located?
    • Incorporated into Absorption, salvage and excretion. David notMD (talk) 03:24, 22 August 2021 (UTC)[reply]
  • ”alcoholics have an increased risk of vitamin B6 deficiency” there’s so much more that could be said about this. I think at the bare minimum this article should summarize how alcohol intake affects B6 metabolism.
    • Removed mention of alcohol intake as lowering plasma PLP, as evidence limited to two very old clinical trials (PMID 7174224 and 4359937) David notMD (talk) 18:01, 20 August 2021 (UTC)[reply]
  • it is assumed that the reader will know abbreviations such as mmol, nmol/l, mg, but these units should be written in full on first use, and/or linked.
  • the significance of B6 is the biosynthesis of chlorophyll is only briefly mentioned in the “Definition” section; surely this should be elaborated a bit a placed in the “Functions” section?
    • Created a referenced "In plants" subsection in Functions, but removed mention of chlorophyll synthesis, as not supported by ref that was in article or any other literature. David notMD (talk) 10:45, 15 August 2021 (UTC)[reply]
      • Subsequently found confirmation of B6 requirement for chlorophyll synthesis, also plant hormones, so added that, with Parra as ref for both. David notMD (talk) 14:48, 25 August 2021 (UTC)[reply]
  • should mention importance of B6 in nucleic acid biosynthesis
  • the coenzymatic role of B6 in glycogenolysis is mechanistically different than in amino acid metabolism, and is probably worth a mention
    • Better explanation.
  • no mention of how B6 is important in the regulation of steroid hormone action
    • Could not find useful sci literature on this topic. David notMD (talk) 20:05, 24 August 2021 (UTC)[reply]
  • is vitamin B6 deficiency associated with defects in immune function?
    • A lit search found no useful review literature for B6 and defects in immune function (or inflammation). One meta-analysis described and referenced for cardiovascular/coronary disease added to the Research section. David notMD (talk) 15:30, 13 August 2021 (UTC)[reply]
  • no mention that because of its chemical stability, pyridoxine hydrochloride is the primary chemical form used in food fortification and multivitamin supplements
  • what is the role of vitamin B6 in diabetes? PMID 32456137
    • Suggested ref not used. Too much of the evidence in this review was non-human. Evidence divided between diabetes causing low B6 and low B6 causing diabetes. No other literature provided review of multiple clinical trials for higher B6 intake preventing or treating diabetes. David notMD (talk) 10:42, 13 August 2021 (UTC)[reply]
  • have B6 deficiencies been linked to depression? PMID 27655070 PMID 33251075
    • Suggested refs not used, as not specific for B6. Two review refs found and incorporated into the Research section. David notMD (talk) 10:42, 13 August 2021 (UTC)[reply]
  • there is an updated (2020) “D-A-CH reference values for nutrient intake” that might be useful as an additional, more recent source for dietary than two currently used in the article
  • from what source is the B6 used in dietary supplements obtained?
    • Commercial synthesis subsection added with referenced content describing current process for chemical synthesis, also exploration of fermentation biosynthesis. David notMD (talk) 21:35, 16 August 2021 (UTC)[reply]
  • any relationship between B6 and epilepsy? PMID 31340680 Multiple sclerosis? PMID 28875857 Cancer? PMID 28376200 PMID 30271425 PMID 29477221 PMID 31262866 PMID 32208818 Does B6 supplementation help old people with cognition? PMID 28248558
    • PMID 31340680 and 28376200 incorporated into article in Genetic defects subsection and Research section, respectively. The other refs listed were not WP:MEDRS. Other refs found about B6 and cognition (not conclusive). David notMD (talk) 21:03, 12 August 2021 (UTC)[reply]

Based on this, and the existing citations needed tags, I think the article is still quite a ways from meeting the good article criteria at this time. For that reason, I will close this submission as not promoted at this time, and hope the nominator resubmits in the future. Esculenta (talk) 22:53, 11 August 2021 (UTC)[reply]

A good overview provides doi:10.3390/cells7070084, e. g. enzyme names + biochemistry. --Julius Senegal (talk) 07:16, 13 August 2021 (UTC)[reply]

Thanks. Parra 2018 now used several times as a ref. David notMD (talk) 14:50, 25 August 2021 (UTC)[reply]

Added Medical uses and Research sections, and Fortification and Commercial synthesis subsections. David notMD (talk) 16:21, 13 August 2021 (UTC)[reply]

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