Talk:Iodine in biology

Cutting this article

Letters to the editor such as "Environmental iodine deficiency: A challenge to the evolution of terrestrial life?" are not reliable sources. WLU (t) (c) Wikipedia's rules:^simple/_complex 15:36, 9 June 2010 (UTC)

Was done by more than just cutting a letter to the editor. And by the way, who says that letters to the editor are not RS? They are certainly reviewed by the editorial staff of the journal, and getting a letter to the editor printed in a major journal is quite difficult. Is is all very dependent on the journal.

However, this is the major problem in the cutting done here, which was excessive. Yes, the article is a mess, but WP isn't finished. The answer isn't to take every article you see with empty sections and cut it down to a stub, leaving a "needs expansion" tag. This article had more than 50 references, and they weren't all to Venturi (in fact, most were not). Some of the information deleted is interesting, and not contested by anybody as fact, such as the fact that most of the iodine in the human body is NOT in the thyroid and is obviously serving a non-hormonal function, since it's concentrated by the iodide antiporter in those tissues. Furthermore, in evolution, iodine is heavily concentrated actively in many lower organisms that have no thryoxine, and in some higher organisms that use thyroxine as an iodine storage molecule-- they not only have no thyroid glands, but they no hormonal response to thyroxine. A number of papers discuss this, and it's certainly iodine in biology.

The problem of "synthesis" of a certain type is unavoidable on WP. Every article requires SOME synthesis, unless plagarized. If you choose to pick out the synthetic viewpoints of published authors, you're sythesizing in this way. If these authors make some argument, and you choose to pick them out of the literature of millions of papers, then you're making an argument in a way. Even if there's no counterargument, you're making an argument simply by recognizing and summarizing an argument from somebody else. The very nature of an encyclopedia is to synthesize knowledge, which is why WP:SYN would have major problems if it covered all types of synthesis. It is against policy and avoidable, to summarize one argument in the literature and ignore another equally prevalent one, but it is not avoidable not to summarize ANY arguments. However, the only WP:SYN which is nonpolicy is where the editor states a new conclusion which isn't present in any of the originating articles. That wasn't done here, so far as I can tell. Although it may be true that Venturi is quoting his own work in this articl, at the same time much of that work is published in Thyroid, and is peer-reviewed, NOT simply letters to the editor. Moreover, I cannot find anybody in the literature who has major disagreements with these hypotheses. Venturi is not considered a fringe scientist. Nobody really knows for sure what iodine does outside of thryoid hormone, but it surely does many things, and Venturi's ideas are present the best the field has been able to come up with. SBHarris 18:30, 9 June 2010 (UTC)

Can you cite a policy or guideline which states that a letter to the editor is a reliable source, particularly for medical articles? From my understanding they are considered self-published. Most of my trim was before that edit, it was only my last one that was specific to the letter to the editor.

Most of the articles I removed were primary sources, when wikipedia is supposed to be based on secondary. This one is. So is this one, which is also a study of mice. This one starts with "The authors have hypothesized...", which is hardly auspicious, but along with this one could be reintegrated without any real issue (yep, those were overzealous). This one is from 1985 (and part of the general promotion of one particular author - an editor of the page at that).

The article has 8 empty sections, and no lead now. 13 of 35 references were to Venturi, which jumps to 23 if you include multiple citations of the same article, and 24 if you include the iodolipids webpage which isn't suitable as a source. The article also has four references sections. Iodine and breast cancer, in addition to appearing twice, is based on two animal model articles and a in vitro experiment. The DRI section is unsourced (my edit included a source to an NIH document). Iodine and stomach cancer starts with a weasel word and goes on to cite three Venturi articles followed by some primary studies and lab work. Iodine and immunity starts by citing two old articles (25 and 17 years), followed by what looks like one of several possible letters to the editor, two in vitro studies, and a 27-year-old in vitro study. Iodine in salivary glands and oral health has no inline citations but six references (in the third of four references sections). The first I retained for the final version - it looks like a reasonable study given it is published in 2009, in a solid pubmed-indexed journal. But the whole section (i.e. one sentence) is a "might", and is comprised of studies from 1947, 1951, 1985, and 1986, and a primary source from 2007. I only retained the single Venturi study, but did retain that one - I'm not against Venturi, only him promoting his own studies when they are dubious.

In summary - this article is not ready for the main page. If it's not a duplicate of an existing article or coatrack of a single author's viewpoint, it still should be moved to a sub page rather than kept here. WLU (t) (c) Wikipedia's rules:^simple/_complex 19:16, 9 June 2010 (UTC)

(I'm here because I noticed strange editing patterns by Sebastiano venturi.) I'm an absolute layman, but as an editor WLU's version looks much more like an encyclopedia article to me than this inaccessible mess. Sbharris, if you believe that there is some meritorious content in the longer version, maybe you could selectively integrate it into the shorter version?  Sandstein  19:42, 9 June 2010 (UTC)

I'll also totally own up to removing some sources that would have been suitable ([1]; [2]). If it's acceptable, I'll glady revert to my version but summarize and include these sources as well. WLU (t) (c) Wikipedia's rules:^simple/_complex 19:49, 9 June 2010 (UTC)

Okay. No argument that the previous article was a mess. But it had a lot of salvagable refs in it, and so long as you keep them and what they teach, I'm okay with it. And again, letters to the editor in science journals range from very carefully vetted and reviewed, to mere political opinions. Some journals have a major part of their science content labeled as "letters," which are merely short science articles or reviews. Sometimes the "letters" section is more rapidly reviewed. If you're a layman in this area, you'll have to take my word for it that these things are very often reviewed much more carefully than opinion letters-to-the-editor (which also exist, even in science journals). Basically, if the topic is scientic and the letter is referenced, you can think of it as a short review. Indeed, it is the secondary source (review) you ask for. Indeed, what sort of thing satisfies you? If it's a primary research paper, you complain that it's primary (even though the "discussion" section of primary sources is actually NOT a primary source in that sense). And if it's a scientific review, you complain that it's full of opinions and hypotheses. You're obviously not going to be happy with a teriary encyclopedia of another stripe. And you don't want writers here to synthesize on their own... Does that leave anything? SBHarris 20:19, 9 June 2010 (UTC)

I can't see a LttE being good for anything except a clear opinion by the letter writer, but we can always ask at the RSN. As I hope I pointed out in my assessment above, I don't think it had many salvageable sources - primary sources are good for discussing the results of single experiments, which are rarely considered meaningful. Otherwise, you can't say "Iodine prevents cancer" if the study is of rats, or rat cells - at best you can say "iodine prevents cancer in rats" which isn't very meaningful. Based on what I saw, its imply looks like the research in the area is preliminary, not conclusive. That secondary sources use the word "hypothesis" means, in my opinion, that it's not proven. In other words, it's again one author's (considered) opinion but it's not yet a scientific consensus. There's a considerable difference between this review article and for example, this article - one summarizes a whole bunch of theoretical opinion, the other is a conclusive statement about a mature body of research. That the one author is also the editor adding the information, makes me more skeptical.

Again, I'm not opposed to the secondary sources - my first reply to your comment was to flatly state this. But this can hardly be considered a settled area, and in unsettled areas, it's easier for a POV to be pushed, and having so many primary sources about nonhuman and cell/petri dish experiments would seem to strike at the very essence of why we don't use primary sources.

As a general comment, I would use a tertiary source for basic information, but rely more on secondary sources as is appropriate per PSTS. Also, the page is currently in it's "horrible mess" version. If I replace the two secondary sources, would anyone object to reverting to my previous version? WLU (t) (c) Wikipedia's rules:^simple/_complex 20:45, 9 June 2010 (UTC)

This article is currently putting forward a very implausible and novel idea about iodine being a major antioxidant, and that iodine and selenium were important in the evolution of antioxidants. This version of the article also contains serious factual errors (GSTs as selenoproteins - just wrong!). I favour cutting most of this material, since just because it is cited, doesn't mean it is reliable. —Preceding unsigned comment added by TimVickers (talk • contribs) 04:48, 10 June 2010 (UTC)

Tim, it's not quite "wrong" that GST's have no selenium. Some do. All GST's have a peroxidase subunit, which is a dimer that can be two selenium-containing GSHpx type Se-peroxidases, one with Se and one without, or both without. So it's optional. Iodine as simple iodide does function as an antioxidant in algae (that's why they have so much of it-- it was discovered from kelp ash), and it works in kelp very much like GSH does in higher organisms, and it's a very funny coincidence that the GSH-px enzymes and the deiodinase enzymes (which provide free I- from T4 stores) are phylogenetically related, and probably evolved from the same precursor. It does indeed look like Se now replaces some of I-'s function via GSH production. And again, it is simply not true that the role of I- in biology is merely to make thryroxine, and role of thyroxine is to stimulate metabolism in mitrochondria, end of story. That's not even true in humans. SBHarris 19:25, 10 June 2010 (UTC)

You're confusing glutathione S-transferases (GSTs) with the Se-containing glutathione peroxidase (GPx). This is easy to do, since GSTs also have glutathione-dependent peroxidase activity. However, this depends on GSTs activating the thiol as it is bound in their active site, not on using the thiol as a source of redox equivalents to reduce a selenocystine residue (GSTs ahve a ternary mechanism, whilst GPx have a ping-pong mechanism). This is one of the few topics I'm 100% confident on, since I did my thesis on purifying an S-transferase that had a peroxidase activity! :) Tim Vickers (talk) 20:55, 10 June 2010 (UTC)

Yes, looks like you're right. I was fooled by the fact that there are non-Se GPx's. Interestingly, there are Se-GSTs but they're artificial [3]. Guess what-- they act like GPx, with the ping-pong kinetics and all. So that's a selenium effect. Otherwise the enzymes are fairly homologous. Anyway, please the address the rest of what I said about iodine. This article is improved a bit by saying that iodine is hypothesized to be an antioxidant in people, but the best evidence for its being an antioxidant is in algae. And the name of this article is "iodine in biology" not "iodine in human biology." There are many organisms that use iodine for reasons other than thyroid function, and thyroxine itself appears in biology before it seems to play any hormonal activity. At least, thyroxine makes certain protozoa (the celiate tetrahymena) grow faster. What's up with that? SBHarris 23:06, 10 June 2010 (UTC)

The idea that it might be an antioxidant in mammals is very dubious (it isn't even mentioned in reviews such as PMID 10746354) and although it could be mentioned in passing, I'd think there are many actual facts to discuss before we'd need to add dubious hypotheses to the article. You're right that it would be fine to add some stuff on algae, if there is any literature showing this to be true. As to other thyroxine functions I don't know, I'm not an expert in hormone function I'm afraid, just in antioxidant metabolism. Tim Vickers (talk) 03:19, 11 June 2010 (UTC)

Given this (I respect TimVickers opinion enough to consider him a MEDRS - making me a horrible, horrible hypocrite for which I feel awful) I think I will revert to my version, but replace the two sources that I believe are considered reliable. WLU (t) (c) Wikipedia's rules:^simple/_complex 12:47, 10 June 2010 (UTC)

Done and done. WLU (t) (c) Wikipedia's rules:^simple/_complex 13:03, 10 June 2010 (UTC)

Countries do not agree on upper limits

There is unresolved safety science, as the U.S. sets an adult Tolerable Upper Intake Level (UL) at 1,100 micrograms while European Food Safety Authority uses 600 micrograms and Japan 3,000 micrograms. In 2004 the World Health Organization identified adult UL as 30 micrograms per kg body weight, or 2,100 micrograms for a 70 kg (154 lb) adult.David notMD (talk) 22:28, 1 February 2017 (UTC)

Iodine status in U.S.

Text and references below also in TALK for Iodine Deficiency. David notMD (talk) 17:59, 7 September 2017 (UTC)

An update of U.S. iodine status was published in 2011: Caldwell KL, Makhmudov A, Ely E, Jones RL, Wang RY. Iodine status of the U.S. population, National Health and Nutrition Examination Survey, 2005–2006 and 2007–2008. Thyroid. 2011 Apr;21(4):419-27. Caldwell and others use urinary iodine concentration as micrograms per liter because >90% of consumed iodine ends up being excreted in urine. Definitions for mild, moderate and severe iodine deficiency are set at 50-100 ug/L, 20-50 ug/L and <20 ug/L. Caldwell reported about 1% of U.S. population severe, 8-11% moderate and 20-32% mild. Some age groups more likely deficient than others.

NHANES data and Caldwell's report are based on urinary iodine concentration (UIC) rather than calculating iodine intake from foods. This 2016 reference compares food intake surveys versus UIC to consider whether assessment of iodine status can be improved: Juan W, Trumbo PR, Spungen JH, Dwyer JT, Carriquiry AL, Zimmerman TP, Swanson CA, Murphy SP. Comparison of 2 methods for estimating the prevalences of inadequate and excessive iodine intakes. Am J Clin Nutr. 2016 Sep;104 Suppl 3:888S-97S.

Pearce 2016 points out that UIC is a valid population assessment tool, but does not indicate how individuals are adapting (or not) to low iodine intake. Discusses thyroid hormones and perhaps thyroglobulin as biomarkers: Pearce EN, Caldwell KL. Urinary iodine, thyroid function, and thyroglobulin as biomarkers of iodine status. Am J Clin Nutr. 2016 Sep;104 Suppl 3:898S-901S. doi: 10.3945/ajcn.115.110395. Review. PubMed PMID: 27534636.

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more needed

Below the hypersensitivity section, visible only in edit mode, are suggestions for more content. David notMD (talk) 10:46, 2 March 2021 (UTC)