Talk:Vitamin D

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Talk:Vitamin D/July 2003 to August 2006

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[edit] Evolution of human skin color

"Melanin screens UV rays oflight so dark skin is much less efficient at generating vitamin D. It would therefore be expected that people with darker skin originally with lighter skin would suffer from deficiencies more frequently, especially if they live at higher latitudes or have an urban lifestyle, and there is much evidence that this is the case. Vitamin D deficiency and osteomalacia are known to be endemic in dark-skinned populations in the UK (particularly those from South Asia)."

Isn't this the very selective pressure that favored fair skin in Europeans and Asians? If so, this should be mentioned (with appropriate source). — Philwelch t 07:57, 23 July 2006 (UTC)

The article suggests that it's near impossible to get proper vitamin D in winter at high latitudes. If this is the case, I wonder why Inuit peoples aren't very pale when considering they historically have lived near the Arctic Circle. Peoplesunionpro 17:41, 15 September 2006 (UTC)

They would get a lot of vitamin D from their diet. The kinds of foods they eat has plenty.WolfKeeper 17:50, 15 September 2006 (UTC)

[edit] Other area's of action

I have a small problem with the 'classical' nature of this article. I appreciate the acuracy of most of the info relating to synthesis, calcium homeostasis etc. However, apart from a few mentions, the actions of vitamin D in the brain are largely ignored. In terms of synthesis, 1,25 vitamin D3 (the active form) can be synthesised in the brain and converted to 1,24 vit D3. The steroid argument is neither a yes or no. Vitamin D3 can be considered a 'neuroactive steroid' due to local synthesis in addition to rapid non-genomic effects. The fact that the vitamin D receptor (VDR) belongs to the steroid superfamily of receptors also supports this idea.

In regards to other comments already added. Vit A and D have complex interactions due to the VDR creating heterodimers with the RXR (vit A receptor), this isn't my area of expertise however. Vitamin D overdoses extremelely rare as mentioned and warrant a lot less discussion than that of the actual healthy level of vitamin D. The statement 'levels should be between 40 and 60 ng/mL (100 to 150 nMol/L) for optimal health' is incorrect or innacurate atleast, you find me a paper suggesting this is the level for OPTIMAL health and I will find you a paper that says a different level. As far as I am aware, we aren't sure what a healthy level is, different countries have different levels of fortification built around different guidelines. The lack of understanding regarding vitamin D's effects outside of calcium/phosphorous homeostasis is too limited to accurately quantify a healthy dose, this should be mentioned also.

Lastly, there should be more focus also on the anti-cancer research being done with vitamin D and the epilogues be created for this purpose. To me this article appears to be a well documented view of vitamin D 10 years ago and needs critical updates according to new research which should also be reflected as a larger sum of the total article. I would add to it myself but I am a beginner at wiki-ing...

please feel free to add any comments regarding disagreement with the above, I am not scared of critism and I love a good debate :) I have purposely left cites out for two reasons, 1. I am lazy 2. cites are only needed in the article or when an alterate opinion has been presented, when this is done I will add cites :) —The preceding unsigned comment was added by Malarac (talk • contribs) 20:45, 24 September 2006(UTC).

[edit] Snow?

Article says: "For example, in the United States, those living north of a line from San Francisco to Philadelphia (about 40 degrees of latitude) will not be able to produce it in significant quantities for 3 to 6 months a year." What about those that often live around snow cover during winter? Snow reflects a high percentage of UV. Peoplesunionpro 19:10, 30 October 2006 (UTC)

[edit] Problem? (this should be on the talk page)

I was about to fix a syntax error when I came across this. This should not be in the article space, it appears to be some sort of argument:

I have moved the "problematic" parts of the section What is it: vitamin, steroid or secosteroid? here.

(The following paragraph is extremely contentious. It cites people who have never published in the field of vitamin D nutrition, and it confuses vitamin D with the hormone made from it. The paragraph is interesting because it is an example of why it is so difficult to provide the public with vitamin D in doses high enough to actually make much of a difference to the health of adults. While the author may have been well intended, the result here is a superficial confusion that only pretends to be well cited science):

[1]

In May 2006, Professor Ronald M. Evans, a Fellow of the Salk Institute, delivered a continuing medical education seminar to FDA's Center for Drug Evaluation and Research. In response to a question of what the impact on public health policy should be, given that "vitamin D" is actually a secosteroid, rather than a vitamin, he indicated that he would not supplement with "vitamin D" in the food chain.[2] This position is also supported by new evidence that vitamin D supplementation is harmful in many chronic autoimmune diseases (see section on "In Chronic Disease" below), and not just those previously identified (sarcoidosis, granulomatous malignancy such as lymphoma, oat-cell lung cancer, or when cancer has spread to the bone).[3]

Thus, based on its activity, vitamin D is most accurately viewed as a secosteroid with a high degree of steroidal activity. This indicates the need for further investigation of whether vitamin D supplementation is generally beneficial.--DO11.10 23:12, 2 November 2006 (UTC)

Oh dear I've found more:
An equilibrium is achieved in the skin whereby longer exposure to UVB simply degrades the product as fast as it is generated. Animal species evolved through natural selection to survive optimally in sunshine. Excessive synthesis of vitamin D from prolonged sun exposure is highly unlikely. In the 1960's it was thought that darkly pigmented skin existed to protect against vitamin D toxicity; however, dark skin is the default skin color of humans, it prevents breakdown of micronutrients in dermal capillaries. White skin was favored by natural selection because the mis-shapen pelvis of young women with rickets would have resulted in death because of a constricted birth canal.
Strictly speaking, vitamin D is indeed a true vitamin. In fact, the first vitamine, "antirachitic A" was determined based on the bioactivity of vitamin D. That is, the thing that cure rickets was the thing that led to what we regard as a vitamin. How ironic that some now think that vitamin D is not a "true vitamin", because it can be manufactured by the body. This semantic debate reflects a misinterperetation discussed elsewhere in this encyclopedia, under "vitamin".
These MUST be referenced by a reliable source.
Update: I am reverting edits by 207.188.64.6 (talk • contribs) this page back to the version by 24.44.168.110 (talk • contribs). These kinds of additions to articles are not acceptable, and arguments should be initatied on the talk page.--DO11.10 23:33, 2 November 2006 (UTC)

Response to the paragraph above. I am an active scientist specializing in the vitamin D for over 3 decades. I do write vitamin D articles in REAL encyclopedias. I am at the point where I am giving up on trying to help out Wikipedia. The concept for the encyclopedia is nice, but where do you separate real science from superficial misinterperetation?

The writer of the preceding paragraph is trying to function like a good editor. But how unfortunate that the writer needs to revert to a "reliable source", and insist on "discussing" these things on this page instead. I WAS the person who initiated this kind of discussion (I wrote item 4 above), but after many months, there is zero evidence anybody notices. I tried to fix up the text of the vitamin D article, but evidently need to add literature citations? I don't have the time to figure out how to do that. Encyclopedia entries usually don't include more than a couple of key citations. The list of citations to the Wikipedia vit D article was so long and often useless, that I saw little point to adding anything more of them (you could reference back to Wikipedia's own definition of "vitamin" where I did provide references, Stedman's Medical Dictionary for one, but who takes that seriously?).

In a democracy like Wikipedia, the garbage piles up, and the vitamin D article is showing more nonsense information than it should. The article is repetive and contradictory, because the article has become too long. A contributor really has to assimilate a ton of information before it is possible to add anything new or useful to it.

I for one have no time to fix up this article if my efforts have to be second-guessed. Sorry, I know the previous writer was being a well-meaning editor, but the process of writing this kind of encyclopedia is just not working out here. This article is getting out of hand.—The preceding unsigned comment was added by 207.188.64.6 (talk • contribs).

First of all, please let me be the among the first to welcome you to Wikipedia. It was never my intention to make you feel unwelcome. I hope that you take the time to review the changes I have made to the Vitamin D article. I went back over your additions, and found that you had made several needed and useful contributions. The problem was the addition of some argumentative language that you included with those useful contributions. I have added many of your contributions back, save these argumentative pieces (and a section that I could not easily verify). As I mentioned above I edited the page with the intention of fixing a syntax error that occurred right below one of your edits, which is why I noticed it and removed it. The rest of your edits, in my mind, were then tinged with an air of suspicion. I hope that you reconsider your comments above, I for one would value contributions such as the useful ones you added. (But please no arguments on the article page.)
After reading, (and rereading this article a number of times) I agree with you that it has some major and distinct problem that are not easily fixed. While I do not know what your specific issues were some things that I noticed were 1) The steroid/vitamin debate is, in addition to being wrong, a moot point [regarding whether or not people should take supplements]. Also, I believe that the statements made by Ronald Evans were either misrepresented or taken out of context, as his published record does not indicate his expertise on the subject of vitamin supplements. 2) A heavy reliance on articles written by one author, and members of the same group. 3) Articles by other authors appear to be added as "puffers" in order to make a connection, that has not been proven, appear more scientific. 4) Overall repetition and contradiction that makes the article confusing, I have attempted to fix some of this. It was only with great trepidation (or trepination:))that I did not delete several sections of this article, I can only hope that other editors, such as yourself, see fit to adopt the article, and make it into what it should be.--DO11.10 23:41, 4 November 2006 (UTC)

[edit] Objectivity?

I do not believe that the section on vitamin D and chronic illnesses is objective. Virtually all of the findings are from Dr. Trevor Marshall, and while the section talks of 'increasing recognition' of his findings, the truth is that he has been unable to get them published in any medical journal and is frustrated because they have not been met with recognition, but scorn. I am not an expert, and Marshall could be right -- but his views are far from mainstream or accepted, and should not be presented as such. --Garsecg

The comments of the user above piqued my interest so I set out to see if what he/she asserted was correct. In fact I find that according to the following article there is little current research that suggests that any of these diseases are caused by CWDB
Cell Wall-deficient Bacteria as a Cause of Infections: a Review of the Clinical Significance J Int Med Res 2005;33(1):1-20.
"While there is no direct evidence that their presence results in disease, laboratory data suggest that CWDB (Cell Wall-deficient Bacteria or L-form bacteria) are intracellular organisms that can revert to wild-type bacteria (WTB) outside the cell. CWDB are suggested to up-regulate to a more aggressive patho­logical form when an adverse environment threatens their survival inside cells, and they may in that theoretical situation cause symptoms of disease. Difficulties in proving this theory limit the acceptance of CWDB as disease-causing organisms. CWDB do not fulfil the first and third post­ulates of Koch, and many micro­biologists do not believe they cause any harm to the host."
About the specific studies cited in THIS article; "There was no uniformity in the methods described in these studies and most of the studies that have been conducted in the setting of rheumatology and osteomyelitis are at least 20 years old. We have not found any RCTs (randomized clinical trials) in this setting that have attempted to link CWDB to clinical outcomes, so the conclusions from the case reports discussed above should be interpreted with caution."
Finally the authors conclude that: "The techniques used to identify CWDB are not uniform and many are questionable. In addition the evidence used to argue for their clinical significance is mainly based on case reports or small prospective series. For these reasons many are skeptical about the clinical significance of CWBD and recent clinical trials have also questioned the relevance of these atypical organisms to disease."
Therefore, all statements and references to CWDB and L-form bacteria will be removed since any relevance in this article is directly related to their ability to cause disease. I will check out several other parts of this article, if anyone has any thoughts...--DO11.10 03:50, 23 November 2006 (UTC)
The following comment was left on my talk page:
to DOI11:10 re: Your rejection of our peer-reviewed publications on Vitamin D and Disease
Dear Sir/madam,
I notice that you are deprecating the learned work of myself and my professional colleagues. I sign my name to my work, but I have looked in vain for a name or a telephone number that I could call to contact you. I was taught that science is based on collaboration, not on suppressing the work of others. I would welcome a chat so that we can reconcile the misunderstandings which seem to have arisen.
Sincerely
Professor Trevor G Marshall, PhD, Director, Autoimmunity Research Foundation
Trevmar 04:01, 28 November 2006 (UTC)

In response: I am not sure how you can conclude that I am "deprecating the learned work of you and your professional colleagues". I presented information from the paper I cited in which the researchers concluded that CWDB are not responsible for the clinical manifestations of disease. I then removed the statements about CWDB and disease for the reasons I stated above. That, in my opinion, is "science", not "suppressing the works of others". Addressing my edits, I do not feel that they were heavy handed. In addition to removing the CWDB statements (in all about five sentences) I moved a bunch of material to improve the article flow, deleted some material that was repeated in the article, adjusted the references so that they were uniform, deleted several references that did not seem to be applicable or were only marginally useful (free abstract only with no real relevance on the abstract page), and added full text links to several references. Most of these edits had very little to do with your work. Also, I notice that while you accuse me of the above, you did not contact Garsecg, I wonder why that is?--DO11.10 17:54, 28 November 2006 (UTC)

Dear DOI11:10,

    • Guys, there is life beyond the Internet - only a very small fraction of medical knowledge resides on the Internet - text books, conferences, and direct collaborations overwhelm the subset of knowledge to be found online.

I made a civil suggestion to you, a REAL WORLD suggestion, in relative private, that you phone me so that we could talk through your misunderstandings. I am saddened to see the manner in which you have responded.

As for contacting 'Garsecg,' I clicked on the link for his name and got nothing. No identification, no email address. So what am I expected to do? Is there some way for me to contact this Garsecg??

    • Sincerely, Professor Trevor G Marshall, Director, Autoimmunity Research Foundation.

Trevmar 10:50, 29 November 2006 (UTC)

Considering that the conversation that you propose to DO11.10 is directly related to this page I think that it is completely appropriate that they would then post it here for discussion. And while you are suggesting a "real word" solution not everyone feels the need to talk to people in the real world to solve a problem that is occuring online. I know I wouldn't be willing to pick up the phone and call anyone from Wikipedia to resolve anything.
I don't feel that DO10.11's edits were done to "suppress" your work and (keeping in mind I knew nothing about the subject until viewing the page) the edits they made seem even and not directed at causing someone distress but at actually improving the article. Nigelthefish 20:35, 29 November 2006 (UTC)
Your insistance that I contact you "in private" deeply concerns me, and I will not contact you "in private" to further discuss my edits, as it would deprive other readers of reading for themselves what you have to say regarding this matter.--DO11.10 18:21, 30 November 2006 (UTC)

[edit] Vitamin D in Chronic Illness

In the previous section Garsecg writes, "I do not believe that the section on vitamin D and chronic illnesses is objective. Virtually all of the findings are from Dr. Trevor Marshall." On November 23, 2006, DO11.10 cut the section "Vitamin D in Chronic Illness", perhaps for similar reasons.

I did not delete the entire section--DO11.10.

The question of the section's objectivity is worth discussion.Sure, the section may have been ripe for the inclusion of a contrary viewpoint. What I'm going to take issue with here is DO11.10's choice to completely excise the entire section. That was wrong.

Well since you bring it up, lets take a look at the section as YOU (Palbert (talk • contribs • count)) wrote it (my comments are in plain text in parenthesis--DO11.10):

There is increasing recognition that Th1 immune inflammation, occurring in rheumatic diseases can result in excessive numbers of activated macrophages converting 25-hydroxyvitamin D (25D) to its active 1,25 dihydroxyvitamin D (1,25D) hormonal form.[9][8][13][14]

(8??, 9 is a paper written by Dr. Marshall, 13 is from 1991, increasing evidence?, 14 is about Crohn's disease and says the 1,25D comes from intestine I don't see any mention of macrophages)

This can lead to vitamin D dysregulation/hypersensitivity, which can lead to hypervitaminosis D, hypercalcemia and other symptoms. This is recognized as occurring in sarcoidosis and other diseases.[21]

Serum vitamin D, measured by the precursor, 25D, may appear to be deficient in chronic diseases in which vitamin D dysregulation occurs, because it is being depleted due to excessive conversion into the active 1,25D form by macrophages.[21] (This happens in the kidney not by "active" macrophages [1]) In this situation, supplementation with vitamin D may lead to an even greater elevation of an already elevated level of the 1,25D hormone.[9][8]

(The medical community offers an opposing hypothesis that Vitamin D (as a Vitamin D Receptor, VDR ligand) induces Dendritic cells to acquire tolerogenic properties that favor the induction of regulatory T cells rather than effector T cells[2]. In light of this raising the level of VDR ligand by increasing Vitamin D would treat several chronic/autoimmune diseases who's primary etiologies involve effector T-cell mediated inflammation.)

Marshall showed that elevated levels of 1,25D are able to cause dysfunction of alpha 2 thyroid receptors and glucocorticoid receptors, thus interfering with endocrine function and the adaptive immune response.[5] (There is that name again.)

Research on vitamin D[8][10] has also focused on its role in combating viruses and bacteria. Tiny L-form bacteria, named after the Lister Institute where they were first described by Kleinberger-Nobel in 1934.[22] L-form bacteria lack a cell wall and can hide inside cells, including immune cells, like macrophages. There is increasing evidence of L-form bacteria in diseases like systemic lupus erythematosus,[23][24] rheumatoid arthritis,[25][26][27] Crohn's disease,[28] sarcoidosis[9][10][29][30][31] and multiple sclerosis.[8][32]

(My citation above, and at least a half dozen more papers, show that L-form bacteria do not cause these diseases. Also this "increasing evidence" is taken from papers published in the following years: 1984, 1982, 1989, 1996, 2002, 1982, 2000, (and another of Dr. Marshall's papers), that doesn't sound like "increasing evidence" to me.)

Molecular modeling research[33] indicates that when 25D is high enough, it actually displaces 1,25D bound to the vitamin D receptor (VDR). This interaction may block innate immunity and bacterial killing, suppressing a reaction associated with bacterial killing, called the Jarisch-Herxheimer Reaction.

(The Herxheimer Reaction refers to the release of endotoxin when large numbers of organisms are killed by antibiotics in syphilitic tissues; believed to be due to a rapid release of syphilis antigen and is associated with allergic reaction in the patient, the association here baffles me?)

This anti inflammatory effect may explain why vitamin D gives appears to be helpful in the short term. However, if L-form bacteria are proven to be the underlying cause of these diseases, this suppression of the inflammatory innate immune response may allow bacteria to increase, causing disease.[33][8][10] (How can you reference a hypothesis, it is a question???) The immunosuppressive effect of vitamin D is similar to the effect of steroid hormones, which is not surprising, as it binds to steroid receptors(as discussed above).

(Again, my citation above, and at least a half dozen more papers, show that L-form bacteria do not cause these diseases.)

The success of a new antibacterial protocol[34]

(This link is to Dr. Marshall's foundation and this protocol is called The Marshall Protocol)

that includes lowering of vitamin D levels, supports the importance of vitamin D dysregulation in many chronic diseases.[8][10][9] (Dr. Marshall's papers) The role of vitamin D and the vitamin D receptor (VDR) is also shown by the effectiveness of olmesartan, an angiotensin receptor blocker, as part of this new protocol.

(That's Odd both the wikipedia article and the Physicians Desk Reference say that this medication is prescribed for high blood pressure, neither make any mention of the vitamin D receptor (the VDR))

Olmesartan acts through binding to the VDR, among other effects.[9][33] (Again, Dr. Marshall's papers, this is starting to seem a bit biased)

This new research on vitamin D's effects and the role of vitamin D dysregulation may require reinterpretation of much past research supporting vitamin D supplementation in the prevention and treatment of many chronic diseases.[8][10] (Again, referencing and idea not a fact)

So it was for those specific reasons that I deleted the PARTS of this section that I did, the rest was moved into the overdose section. Okay back to your post---DO11.10 23:32, 29 November 2006 (UTC)

The preponderance of current research has it that: 1. Vitamin D is indisputably immunomodulatory, and 2. Vitamin D has a significant and increasingly documented role in chronic illness.

I agree with point one and point two.

Dr. Marshall does have a body of peer-reviewed research on Vitamin D in chronic illness, and so do a substantial number of other researchers, a number of whom were also mentioned-- Rasjaree, Mawer, Abreu, etc. In any case, there is certainly enough published research here to merit inclusion in a Wikipedia article.

Rasjaree, Mawer, Abreu, they're still there.

If I may offer my most objective take on this issue, the debate is not whether there is any such connection between Vitamin D and the immune system. Rather, it is whether chronic immunological-type diseases are in fact autoimmune or not. (You may think I'm straying, but I'm not.)

Since this article is about vitamin D, the relevance to vitamin D seems crucial to any debate.

There are a number of researchers, some of whom think chronic illness is caused by an overactive Vitamin D receptor; others assert (in peer-reviewed research and in significant numbers) that chronic illness is caused by an underactive VDR. Knowing what we know now, no article about Vitamin D or the immune system can ever be complete without some sort of substantial discussion of the other.

But you don't present ANY of this "peer-reviewed research and in significant numbers" that opposes your viewpoint. That violates Wikipedia policy WP:NPOV.

I try to make a habit of not questioning the integrity of another Wikipedian, so I'll just say once more that DO11.10 made a mistake when s/he cut the whole section, "Vitamin D in Chronic Illness." What s/he should have done was try to assiduously incorporate into the article what I would call here the alternative hypothesis. The thinking to which Dr. Marshall subscribes is sufficiently adopted among large segments of the medical research community and asserted in published research that to completely leave it out would be a disservice to readers of Wikipedia. Palbert 01:08, 29 November 2006 (UTC)

Alternative hypothesis?? I notice that you didn't include any alternative hypotheses in this section when your wrote it, although the papers were out there. Further the article aboutCell Wall-deficient Bacteria and disease is not "alternative", it flatly refutes the connection you attempt to make. And if "The thinking to which Dr. Marshall subscribes is sufficiently adopted among large segments of the medical research community" where are those references?
As for your insinuation regarding my integrity I think that my User contributions address my integrity quite clearly.
As an aside a simple Google search turns up a Paul Albert who appears to be a friend/patient of Dr. Marshall's Paul Albert Posted: Mon Apr 17th, 2006 08:30, seems that might be the same person as Palbert (talk • contribs • logs), which sounds to me like a Conflict of Interest.--DO11.10 23:32, 29 November 2006 (UTC)

[edit] "not everyone feels the need to talk to people in the real world"

This thought from 'Nigelthefish' (above) says it all. Yet you are collaborating in creating a work-product, Wikipedia.org, which is being read by real people, many of whom are sick and looking for answers. Real people are being influenced by what they read here.

I would remind you that I am at least the second expert who has registered their disgust with the way this science is being edited. Like my colleague from Canada (207.188.64.6, above), I am appalled by the misplaced energy I see being displayed here.

Sincerely, Professor Trevor G Marshall, PhD, Director, Autoimmunity Research Foundation.

Trevmar 16:11, 30 November 2006 (UTC)

You are right, this article is being read by people who are looking for answers and being influenced by what they read here, that is the reason why the people who read this article should be exposed to accurate, complete and unbiased information. It is this reasoning that promted me to remove, from this article, the grossly misinformed and inaccurate information from the sections that I did, as I outline above.
The case involving IP user 207.188.64.6, is vastly different from this one, to compare the two situations would be, to use a cliche, like comparing apples to flying cars.
In summary, I stand by my current edits, and will continue to make improvements to this article in the future.--DO11.10 18:39, 30 November 2006 (UTC)

[edit] Before working on a project

It is a good idea to learn how it works. WP is not short of essays on how it works. Midgley 15:09, 3 December 2006 (UTC)

That is certainly good advice. But to whom/what are your comments directed? If you feel that I have done something wrong, please tell me or I am likely to do it again.--DO11.10 21:35, 3 December 2006 (UTC)

[edit] Vitamin D3 created 'in' or 'on' the skin

in her 1954 book, Adelle Davis wrote, "Most medical textbooks say that vitamin D is formed by sunlight on the oils IN the skin although it was proved 16 years ago[A.C. Helmer and C.H. Jansen] that the oils must first be ON the skin, then exposed to ultraviolet light, and later absorbed back into the body. If persons take a bath before going into the sunshine, the oils are washed off, and no vitamin D is formed; if they do not bathe before exposure to sunshine but bathe immediately afterward, the oils are removed before the vitamin can be absorbed into the body." what is the latest information?Sanfranciscojim 21:57, 18 January 2007 (UTC)

I came to this article looking for an answer to the question of "where specifically is Vitamin D produced?" and was unable to find that information. Is it produced by cells of the epidermis, the dermis, or both? What is the role of oils, as brought up in the above comment? Provophys 18:28, 19 January 2007 (UTC)

[edit] Answers

Vitamin D is produced photochemically IN the skin from 7-dehydrocholesterol (not an "oil").

Epidermal skinlayers
Epidermal skinlayers

First off some background about the skin: It consists of two primary layers: the inner dermis, composed largely of connective tissue, and the outer thinner epidermis (see image). The thickness of the epidermis is <25 um and it contains five strata; from outer to inner they are the stratum corneum, (sometimes the lucidum), granulosum, spinosum, and basale.

"The highest concentrations of 7-dehydrocholesterol are found in the stratum basale and stratum spinosum. Accordingly, these two layers have the greatest capability for production of previtamin D3 and vitamin D3, whereas the other layers have a lesser capability."

Bathing removes dead skin cells from the stratum corneum, you can't "wash off" the deeper spinosum, and basale layers of the skin.

On another note "UVB affects the epidermis, and the two principal determinants [of generating Vitamin D] are the quantity (intensity) and quality (appropriate wavelength) of the UVB irradiation reaching the 7-dehydrocholesterol deep in the stratum basale and stratum spinosum."

  • I will add this information to the article. And to answer the question below, you don't need sunlight to convert D2 (or D3) that you have ingested into active hormone, you just need sunlight to MAKE pre-vitamin D3 from 7-dehydrocholesterol, which is converted to active hormone, only when the vitamin is required, in the kidney.

Hope this helps---DO11.10 19:41, 19 January 2007 (UTC)

[edit] Vitamin D2 vs D3

does one still need to have UV exposure when taking D2 for the correct metabolic process to proceed?Sanfranciscojim 22:06, 18 January 2007 (UTC) —The preceding unsigned comment was added by Sanfranciscojim (talk • contribs) 22:05, 18 January 2007 (UTC).

[edit] Ligand

I added a wikilink to the ligand term in the Role in immunomodulation section, but I'm not absolutely positive that it's the correct term. Could someone knoweldgable about the subject make sure it is correct please? Thanks.WLU 18:25, 23 January 2007 (UTC)

That is the right term- thanks!--DO11.10 21:16, 23 January 2007 (UTC)

[edit] Possible typo in Overdose

Hi,

This is my first time ever posting to wikipidia so I'm not sure how this works. I hope I've come to the correct place.

In the Overdose section the third sentence reads:

Although normal food and pill vitamin D concentration levels are too low to be toxic, because of the high vitamin A content in cod-liver oil it is possible to reach poisonous levels, if taken in multiples of the normal dose.

I am confused by the mention of vitamin A. Either the mention of vitamin A is a typo or (more likely – given my lack of medical knowledge) somehow vitamin A increases the toxicity of vitamin D. If the latter case it true, perhaps, one of the contributors could put in a sentence or two about how high levels of vitamin A can cause one "to reach poisonous levels" of vitamin D.

Thanks (and if I'm in the wrong place please let me know) -Kevin —The preceding unsigned comment was added by 208.237.178.229 (talk) 16:10, 31 January 2007 (UTC).

This is the right place. Yes that was a typo, I think that sentence was directly copied from the vitamin A article or something. I have changed it to vitamin "D". Good catch.--DO11.10 18:50, 31 January 2007 (UTC)

My understanding of this is that the original is correct because it is referring to the toxicity of excessive Vitamin A. For absolute clarity the passage should read, I believe, something along the lines of:

"Although normal food and pill vitamin D concentration levels are too low to be toxic, because of the high vitamin A content in cod-liver oil it is possible to reach poisonous levels of vitamin A, if taken in multiples of the normal dose in an attempt to increase the intake of vitamin D." This should not be difficult to verify...

FrancesB 88.105.136.210 20:50, 1 March 2007 (UTC)

[edit] Citation tag explained

The following addition is dubious.

The toxicity limit on Vitamin D is often questioned. Reinhold Vieth, a published vitamin D researcher, recommends 4000IU per day as an ideal amount for good health and points out that only levels above 95μg/day (3800 IU/day) may cause hypercalcemia.[4] Also, no normal human being (i.e not suffering from vitamin D hypersensitivy or other ilnesses) has ever contracted Vitamin D toxicity, despite the fact that a fair-skinned person who exposes themselves to the sun for 20 minutes can produce up to 20,000 IU per day.

  • The first citation is quite poor, there must be a peer reviewed source out there.
  • "Normal human being" is inappropriate, and pejorative.
  • The second sentence will require citation for the amount produced. But, really, so what? People don't get vitamin D toxicity from the sun, toxicity comes from supplements or industrial accidents this was already stated above in the same passage.--DO11.10 18:22, 12 February 2007 (UTC)

[edit] Stifling Concept Improvement

You, User DO11.10 remind me of the people during the thousands of years of dispute over heliocentrism (look it up) that continually battled against the idea that the Earth was not indeed the center of the universe. You stifle any such improvements over the medical concept of "vitamin" D. Your cardinal rules of which you interpreted the wikipedia guidelines are ridiculously totalitarian. Those who are in the know, not you, don't come here to make immprovements because their ideas don't conform to your rules. It's quite a shame. You have much talent editing wikipedia, however that talent seems to repress ideas and concepts which don't fit your rule book. Wikipedia policeman, I wish only truth to prevail. I hope one day you realize your faults. Cuda918 20:12, 24 February 2007 (UTC)

[Addendum: I have no idea which contributions you have made that I have then removed, as far as I can tell Cuda918 (talk • contribs • logs) has made only 1 edit prior to this one. Also in the past month or so the only content addition that was made to the article was the "toxicity" information above. You will have to be more specific.] I would certainly welcome additions to improve this article provided that they conform to Wikipedia's policies, such as additions that are:
If you find the above guidelines "ridiculously totalitarian" then I think you will find that many dedicated editors of Wikipedia will consistently stifle your improvements. My motivation for editing this article, and all of the other articles I have ever contributed to, is a genuine interest in maintaining the quality of the article and preserving accuracy and I apologize if you take offense to my (own personal) "cardinal rules".
In closing, from the Wikipedia policy that users should avoid personal remarks: Wikipedia prospers on people working together toward improving articles. Anything else – especially attacks directed specifically at users – detracts from the wonderful thing that we are creating here.--DO11.10 05:31, 25 February 2007 (UTC)
It isn't the guidelines, but your interpretation of them. As far as personal remarks are concerned you should try heeding your own warnings. I figured you used this public space as your own personal page/instant messenger anyway. Perhaps it isn't the "dedicated editors" that are the primary mode of stifling concept improvement but the media which is being used. I appreciate this insight you have given me and the talent to which you are on top of things. Cuda918 17:25, 26 February 2007 (UTC)

Excellent Vitamin D Webcasts available I present this here, because my own efforts to modify the regular vitamin D page have generally been deleted. My format for adding to the article does not match up to the criteria of user D011.10, who seems to function as the policeman of this part of Wikipedia. If there is someone suitably qualified to add these to the encyclopedia entry, the following would likely be of interest to some readers.There are now many professional-level webcasts available ensuing from a December 2006 meeting in Washington DC. http://app2.capitalreach.com/esp1204/servlet/tc?cn=asbmr&c=10169&s=20343&e=6950&& Alternatively, there is another more lay-person oriented webcast about vitamin D available at the following: http://www.direct-ms.org/presentations.html

p.s. the use in the article of the term "Vigantol" specifies a brand name. Something that should be a no-no. —The preceding unsigned comment was added by 207.188.64.235 (talk • contribs).

The first of the above links could potentially be included in the external links of the article, depending on their content. I've never heard of the American Society for Bone and Mineral Research, and it looks like it's funded by Eli Lilly, but it might be good if the podcasts have basic info and aren't just pushing vitamin/mineral supplements. I'd say the second one is out - anything with direct in the weblink has to be spam :) WLU 12:30, 26 February 2007 (UTC)

Re: Excellent Vitamin D Webcasts Available: I'm currently researching the effects of UVB light on vitamin D3 synthesis and I have just visited both these web casts. The first is a very interesting (but highly technical) series of research presentations made at a symposium entitled: Contemporary Diagnosis and Treatment of Vitamin D-Related Disorders, December 2006. Not "basic info" but very well presented info. Quite a few of the participants are names I have seen on papers in peer-reviewed journals. It's certainly not "pushing vitamin/mineral supplements", far from it.

The second one is certainly not spam. It is a webcast of a lecture aimed at a "lay" audience by a Dr. Reinhold Vieth (again someone whose name is familiar) and it is made available through the website of what is apparently a small Canadian charity called DIRECT-MS, short for DIet REsearch into the Cause and Treatment of Multiple Sclerosis. I know nothing of this, but it looks completely genuine. The webcast can be accessed directly, bypassing the multiple sclerosis link, at: http://www.insinc.com/onlinetv/directms13oct2005 I would recommend this to anyone as an introduction to some of the more recent ideas emerging from some D3 studies, although some of these findings are still very controversial and I am sure this presentation will not be everyone's favourite, in particular those people "pushing vitamin/mineral supplements" !

FrancesB 88.105.136.210 21:15, 1 March 2007 (UTC)

[edit] Hemp seed

Hemp seed appears to have a lot of Vitamin D. This should probably be added along with shiitake mushrooms as a vegan source. But is it D2 or D3? Badagnani 19:22, 14 March 2007 (UTC)

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