Talk:Vitamin B12

Academy of Nutrition and Dietetics not being flagged as an industry trade group

I added a note to the text regarding Academy of Nutrition and Dietetics being an industry trade group, since their stance on plant and algae sources being insufficient is a clear conflict of interest. It's the same as asking a trade group backed by Kellogs if cereal is sufficient for breakfast.

However it was reverted as "Unnecessary commentary" by User:Zefr. Please explain. mjog (talk) 07:10, 24 November 2022 (UTC)

Your edit was a personal opinion about COI, WP:OR, not supported by a WP:RS source, and was not needed to improve understanding that fermented foods and algae are not practical or reliable food sources of vitamin B12 - an obvious conclusion. The sentence on food or supplement sources of B12 in the AND position paper was sourced to the Institute of Medicine monograph on vitamin B12 and clinical studies of B12 status. AND is a century-old association mainly of registered dietitians and academic nutrition experts - the 2016 position paper is highly cited and a reputable source for nutrients in vegetarian diets, particularly emphasizing the conspicuous point that B12 intake is deficient or absent from vegetarian diets, so must be supplemented or obtained from fortified foods. Zefr (talk) 18:30, 24 November 2022 (UTC)

Potentially misleading Plants and algae subsection of Sources section

Many sections in the article make it clear that vegans/vegetarians shouldn't rely (solely) on natural food sources for their B12 needs. It really, really seems that this is the wide consensus of the medical community as well.

In the Plants and algae subsection however, only a mention at the very end, even that with an attribution, clarifies this, with just one ref. There is a lot of talk however, about fermented plant foods, and seeweed-derived foods. Of the 8 total references, 4 are studies (that seem like primary sources to me) about achieving proper B12 levels in humans with these foods. A named algae species is said to contain as much B12 as liver (with a citation that also looks like a primary source).

This all together is very misleading, and only reading this section and not the others that clarify vegetarians need supplementation or fortified foods, could leave someone very mistaken about the current consensus on this topic.

I suggest we remove the sentence about the "liver-rivaling" algae (very unlikely untrue anyway, as liver is very high in B12) or at least the mention about such supposed concentrations of B12, and make it much clearer that what the consensus is on B12 and vegetarians. I would suggest mentioning pseudovitamins and antivitamins, something algae seem to have. Feels relevant to me.

Sections talking about the need for supplementation or fortified foods for vegans/vegetarians:

- The introduction says that vegetarians and vegans may not get enough B₁₂ without a supplement.

- The Deficiency section makes it clear that plant-sourced foods do not contain enough B12 vitamin to prevent deficiency and vegetarians are also at risk.

- The Dietary recommendations section states that vegans should consume supplements or fortified foods for B₁₂, or risk serious health consequences.

- The Fortified food sections states that vegan advocacy organizations, among others, recommend that every vegan consume B₁₂ from either fortified foods or supplements - with 4 references. 23d49h24 (talk) 20:38, 14 October 2023 (UTC)

23d49h24 I agree. I moved the last sentence to the beginning of the section, deleted the "liver-rivaling" content as misleading (was not clear from the ref that this algae is used as food), and removed a 1977 ref as too old, given that newer refs supported the text in question. If you feel that more can be done to deemphasize the practical value of plant and algae foods, do so. David notMD (talk) 09:24, 15 October 2023 (UTC)

Super, thank you. 23d49h24 (talk) 11:10, 15 October 2023 (UTC)

Nobel laureates

After User:Highfly3442's edit today we have Six people have been awarded Nobel Prizes for direct and indirect studies of vitamin B12: George Whipple, George Minot and William Murphy (1934), Alexander R. Todd (1957), Dorothy Hodgkin (1964) and Robert Woodward (1965). As the citation makes clear, three of these (Todd, Hodgkin and Woodward) were awarded the prize for other work, not specifically on B₁₂. Indeed, Woodward's synthesis work was not even published until 1973! I wonder if we should therefore reword that sentence to something like George Whipple, George Minot and William Murphy were awarded the Nobel Prize in 1934 for their work on the vitamin. Three other Nobel laureates, Alexander R. Todd (1957), Dorothy Hodgkin (1964) and Robert Woodward (1965) made important contributions to its study.(Same citation) Mike Turnbull (talk) 15:32, 19 November 2023 (UTC)

Michael D. Turnbull As the person who raised this to GA in 2020, I will not dispute your proposed change. David notMD (talk) 08:26, 20 November 2023 (UTC)

 Done Mike Turnbull (talk) 14:40, 20 November 2023 (UTC)

Thanks Michael.

I just noticed that you made the record straight.

Although I love Wiki, and have done a lot of editing,I am still learning when I can.

I find Wiki hard to really become proficient at. I don't see where there is clear training available, although there are a lot of articles that, if studied enough, one could succeed in mastery! Highfly3442 (talk) 15:11, 1 March 2024 (UTC)

@Highfly3442 There is not "training", except by doing but there is now a mentorship scheme that many new editors are offered and which was designed to aid editor retention. You can activate this at the bottom of Special:Preferences and then when you navigate to your userpage, you'll see a new tab with a number of features. I suggest you add a small bit about yourself so that you actually have a userpage: see WP:UPYES for guidance. Mike Turnbull (talk) 16:15, 1 March 2024 (UTC)

The amount of B12 absorbed by passive diffusion process

Is there any data on the amount or ratio (percentage) of B12 absorbed by passive diffusion process. I understand that there may be different factors that may affect the passive diffusion absorption, still, is there any data? Maxim Masiutin (talk) 10:34, 25 March 2024 (UTC)

Maxim Masiutin Reference 12 cites some very old work that used radioactive cobalt "Adams and colleagues (1971) measured fractional absorption of radiolabeled cyanocobalamin and reported that nearly 50 percent was retained at a 1-µg dose, 20 percent at a 5-µg dose, and just over 5 percent at a 25-µg dose." This matches up with receptor-mediated absorption saturated at around 1-2 micrograms, with passive absorption being modest. The text goes on to estimate 1% passive absorption was observed with mega-doses. A PubMed search on vitamin B12 supplemention limited to clinical trials demonstrated that high doses increase plasma concentration. Examples: PMID 33513879 showed 1000 mcg/day for a year tripled plasma B12. After 500 ug/day for 8 weeks, plasma was at 340 compared to 180 for placebo. (PMID 23236022). David notMD (talk) 03:41, 27 March 2024 (UTC)

I think that it would be OK to cite these references. Could you please update the B12 article and add summary information on the amount or ratio (percentage) of B12 absorbed by passive diffusion process or if it is not known which share is absorbed by active transport and which by passive diffusion, at least specify percentage of B12 absorbed both ways, since the amount absorbed by active process is negligible. I think writing more about active transport and passive diffusion in the article of B12 is very important. I always considered these issues of absorption very important, especially for those vitamins which are poorly absorbed, such as B2 and B12.

@David notMD -- could you please update the B12 article with that information? Maxim Masiutin (talk) 09:04, 27 March 2024 (UTC)

Also, I read somewhere that 500 mcg once a month in intramuscular injection gives similar plasma B12 levels as daily oral consumption of 1000 mcg, but can't now find the source. Therefore, we can assume that 30*1000 = 30000 mcg orally is equivalent to 500 mcg intramuscular. Maxim Masiutin (talk) 09:07, 27 March 2024 (UTC)

Maxim Masiutin I will undertake rewriting and re-referencing the entire Absorption section, as it is too long, depends too much on ref #12, and the other refs are not appropriate (in vitro, old, a clinical trial, etc). The short Treatment section also needs improvement. I found PMID 36249776 and 30261596 as possible refs. Those and some other review articles on intramuscular describe that after initial frequent intramuscular treatment to treat deficiency, then either oral dosing at 1000 ug/day (with passive absorption estimated at 1%) or intramuscular dosing at 1000 ug once a month, or even every other month, are comparable for prevention of recurrence. David notMD (talk) 11:19, 27 March 2024 (UTC)

Yes, thank you, that was what I meant, suggesting that oral absorption is about 1/30 (3.33%) or 1/60 (1.67%) of the dose of 1000 mcg. Maxim Masiutin (talk) 11:49, 27 March 2024 (UTC)

Treatment subsection revised and two references added. Still need to address the Absorption section. David notMD (talk) 14:03, 28 March 2024 (UTC)

All of Absorption section replaced. Passive absorption described as roughly 1%. Treatment makes clear that intramuscular 1000 ug once per month versus oral, same amount daily. David notMD (talk) 21:12, 2 April 2024 (UTC)

Diagnosis needs work, too

I recently added content at Haptocorrin (HC) that makes clear that functional B12 deficiency can be present even when serum B12 is elevated above the normal range. At issue is the fact that 80-90% of circulating B12 is bound to haptocorrin, and is thus unavailable to cell receptors for transobalamin II, the transport protein that does deliver B12 to cells. HC-B12 is described as circulating storage, but the means for disassociating the complex when needed are not entirely understood. Elevated HC, and thus elevated HC-B12 not available to cells, is caused by cancer, hematological diseases and liver diseases. Same content added here, to Diagnosis. David notMD (talk) 14:40, 31 March 2024 (UTC)