Talk:Vitamin D

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Note: Parathyroid hormone stimulates the activation of vitD so that osteocytes become activates and Ca concentration is increased. —Preceding unsigned comment added by 134.36.123.158 (talk) 17:18, 28 April 2008 (UTC)[reply]

--There are some inconsistencies in the micrograms=I.U. figures---

I seem to recall that 2.5. MGs equals 50,000 IUs. In the middle of the article, different figures do not equate, such as a 5X microgram increase equals a 10X IU increase. The exact figures should be verified and correced. —Preceding unsigned comment added by 71.163.209.112 (talk) 07:49, 18 May 2008 (UTC)[reply]

For some, diet may not be enough for Vitamin D

Legacy recommendations call for people from age 50 to 69 to get 400 international units (IUs) of vitamin D per day and for those over age 70 to get 600 IUs. Many researchers, however, suggest that 1000 to 4000 IUs may be needed. [1] Brian Pearson 04:52, 23 April 2007 (UTC)[reply]

Latitude factor

Following this sentence These wavelengths are present in sunlight at sea level when the sun is more than 45° above the horizon, or when the UV index is greater than 3. it might useful to add that the required solar elevation occurs daily within the tropics, daily during the spring and summer seasons at mid latitudes, and almost never within the arctic circles. The point to make apparent is that for many countries there is an annual cycle of boom and bust, which is a huge factor in the health issues associated with vit D.

Suggestion:

At the latitude of Seattle, Montreal, Venice, and Christchurch NZ the sun rises to this elevation during spring and summer, but not during fall and winter, resulting in annual vitamin D cycles.

I picked well-known, longitudinally distant cities at 45 degree latitude; there are few such cities in the southern hemisphere apart from Christchurch. See List of cities by latitude.

From http://www.theglobeandmail.com/servlet/story/RTGAM.20070428.wxvitamin28/BNStory/specialScienceandHealth/home

For the rest of the population, vitamin D levels tend to be lower, and crash in winter. In testing office workers in Toronto in winter, Dr. Vieth found the average was only about 40 nanomoles/L, or about one-quarter to one-third of what humans would have in the wild.

MaxEnt 14:30, 28 April 2007 (UTC)[reply]

60% cancer reduction

This is a shocking number, and hard to believe on face value. Twice the effect as compared to smoking. I did a little arithmetic on that.

http://www.bccancer.bc.ca/HPI/CancerStatistics/FF/AgeStan/Inc/default.htm

Cancer rates for women in BC run about 330/10,000 per year. 1200 women broken into two equal groups and followed for four years gives you 2400 women-years per group. At a rate of 330/10,000 with a 60% reduction in the non-control group gets you incidence rates of 7 and 2.8. How does one measure 2.8 cancers? Quite possibly, the actual numbers were 10 and 4. 14 total cancers in 4800 women-years is a rate of 291/100,000, which is quite realistic. If it breaks down 7 and 7, you have no result. Standard deviation sqrt(14) = 3.7. It looks to me like both sides of the study are within one standard deviation of a possible mean. I don't know off the cuff how to compute the null hypothesis properly, but it's certainly large enough to cast doubt. MaxEnt 16:24, 28 April 2007 (UTC)[reply]

I thought about this some more. My calculation above assumed age-standardized rates. For a study of this size, it's extremely hard to achieve statistical significance with a mean rate this low. Almost certainly the population was biased toward older age groups to achieve a higher mean rate. Women over the age of 65 have a mean rate four times as high. http://www.bccancer.bc.ca/HPI/CancerStatistics/FF/Rates/incidence.htm If the mean rate for the age-skewed study group was 800/100,000, then 20 cancers are expected in the control group, and the 8 observed cancers in the experimental group (-60%) comes out 2.7 deviations below the mean. The study is much stronger if the experimental population was tilted toward advanced age. MaxEnt 17:47, 28 April 2007 (UTC)[reply]

I would like to know if there has been less tanning recently than in years past when people seemed to believe tanned people were nicer looking and possibly more "healthful" looking. Brian Pearson 03:03, 6 May 2007 (UTC)[reply]

I am confused. The article history shows that the results of this study were (first) added to the article by you. Are you disputing information that you - yourself - added?--DO11.10 00:28, 30 April 2007 (UTC)[reply]

I don't think he is disputing it so much as he is wondering aloud how a reduction of that magnitude is possible. WatchAndObserve 14:56, 6 May 2007 (UTC)[reply]

How can a 60% reduction of cancer be possible? And what is the biologic mechanism that links vitamin D with cancer? A year ago I would have said there cannot be such a link because vitamin D affects calcium and bone cell metabolism which have no connection to most cancers. Or so I thought until I read an article in the November 11, 2006 issue of Science News by Janet Raloff, The Antibiotic Vitamin. The article says that vitamin D hormone 1,25-D is necessary for macrophages to produce antimicrobial peptides in the cathelicidin group to combat virus, fungus, and bacteria infections. The link with cancer is that macrophages also destroy damaged cells and cell fragments such as DNA. By the time a cell becomes malignant, its chromosomes and DNA are a chaotic mess. (See Scientific American, May 2007, pages 53-59.) Most chromosomes in cancer cells are mere fragments or completely missing, some are duplicated, and the DNA is rearranged and mutated. The genetic mechanisms that control growth and prevent unlimited growth, such apoptosis, telemere shortening, and intercellular communication are gone or inactivated. Hence, the macrophages, which kill malignant cells and destroy cell fragments, are the last defense against cancer. Since vitamin D is necessary for phagocytosis, vitamin D deficiency can allow malignant cells to multiply unchecked. Greensburger 17:37, 6 May 2007 (UTC)[reply]

At the very least the astonishing correlation in this study suggests that further research is justified. Staypuft9 16:06, 20 August 2007 (UTC)[reply]

New data is available: http://www.google.com/search?q=Vitamin+D+protects+cells+from+stress+that+can+lead+to+cancer&ie=utf-8&oe=utf-8 Artem-S-Tashkinov (talk) 18:27, 16 May 2008 (UTC)[reply]

Reference questioned

I am taking issue with the following statement:

One recent consensus concluded that for optimal prevention of osteoporotic fracture the blood calcidiol concentration should be higher than 30 ng/mL (US units), which is equal to 75 nmol/L (System International units).

The reference given is http://dietary-supplements.info.nih.gov/factsheets/vitamind.asp, but I don't see this information anywhere on the page. If nobody objects, I will be removing the reference from this statement and adding a 'citation needed' tag.WatchAndObserve 14:59, 29 April 2007 (UTC)[reply]

I have changed the citation.--DO11.10 00:28, 30 April 2007 (UTC)[reply]

I have a doc that states it pretty clearly: [[2]] . Also, if you want you can watch worldwithoutcancer video on google videos, it's a pretty old movie that has had quite some controversy, but it also advocated (somesort of) D Vitamin. Cheers: Mr soros 02:16, 22 July 2007 (UTC)[reply]

Vitamin D; spelling of Mittelstaedt, Martin

Please note that the article entitled "Vitamin D" includes a citation by one Martin Mittlestadt. See citation no. 39. The name is incorrect. The correct form of his name is Martin Mittelstaedt. Cf. http://www.theglobeandmail.com/servlet/story/RTGAM.20070428.wxvitamin28/BNStory/specialScienceandHealth/home Boytinck 17:45, 1 July 2007 (UTC)[reply]

Done--DO11.10 02:29, 3 July 2007 (UTC)[reply]

"A 2006 study published in the Journal of the American Medical Association, reported evidence of a link between Vitamin D deficiency and the onset of Multiple Sclerosis; the authors posit that this is due to the immune-response suppression properties of Vitamin D" the article cited doesn't mention this at all.

External Link Video Add

I'd like to add a video in which Dr. DeLuca from University of Wisconsin discusses the history of the discovery and applications of Vitamin D. The link is http://www.researchchannel.org/prog/displayevent.aspx?rID=3751&fID=345 (this does not automatically open the video). Please let me know what you think. (ResearchChannel 19:42, 17 July 2007 (UTC))[reply]

While the content of this video is great, (from what I saw... the history part was fascinating) the streaming quality was –well– bad. I tried the video in both WMP and Quicktime. In WMP the video paused to buffer seven or eight time in the first minute, and didn't get any better when I skipped around. The Quicktime version was better, no buffering issues, but when I tried to skip I lost the sound(?). Given that the video is 1 hour 18 minutes long both issues will probably hinder it's usefulness here. Granted it could be my settings or something (probably not my connection speed though, I am running at over 2,000 kbps). If it is possible to address these issues, I think that the video is certainly relevant and I would like to add a link. --DO11.10 18:30, 20 July 2007 (UTC)[reply]

Vitamin D in milk

I cannot find this information on the milk page: it is my understanding that Vitamin D is fat-soluble. Does this mean that skim milk cannot be fortified with it? Staypuft9 16:07, 20 August 2007 (UTC)[reply]

My skimmed milk claims it is fortified with D. --Michael C. Price ^talk 16:29, 15 November 2007 (UTC)[reply]

I'm pretty sure most skim milk has at least some fat Nil Einne (talk) 12:22, 27 December 2007 (UTC)[reply]

I read that whole milk contains about 3% fat and skim milk contains about 0.5% fat, but I don't recall where I read it. Greensburger (talk) 17:35, 27 December 2007 (UTC)[reply]

Mortality benefit

In a meta-analysis of 18 studies, vitamin D (mean dose 528 IU) reduced the mortality risk by 7%. Exact mechanisms remain unclear, and more trials are needed. URL JFW | T@lk 21:43, 10 September 2007 (UTC)[reply]

In the Time.com article that discusses this meta-analysis, there is this sentence: " 'Throughout human evolution when the vitamin D system was developing, the 'natural' level... was probably around 50 ng/mL or higher,' writes Dr. Edward Giovannucci. Only in human evolution? Don't other animals need vitamin D too? If so, how do they make it if their skin is covered with fur? Greensburger 23:53, 13 September 2007 (UTC)[reply]

Some of the light will still reach their skin even with fur; and in many cases not all of their skin is covered with fur. Besides, a fair number of animals (particularly furry ones) tend to be carnivorous, and they can extract it from their prey's liver.WolfKeeper 04:27, 14 September 2007 (UTC)[reply]

Apologies for not linking an article, but I read once that furred animals, like cats, lick D off their coats during cleaning after sun exposure. Essentially, they are often 'orally' taking vitamin D from their fur (or prey), as long as they go outside. This is why diabetes (related to D deficiency) is seen in cats that don't go out in the sun, and hunt. —Preceding unsigned comment added by Mo79 (talk • contribs) 11:11, 18 September 2007 (UTC)[reply]

Does vitamin D actually promote reabsorption of calcium in kidneys?

The article currently states, "Vitamin D regulates the calcium and phosphorus levels in the blood by promoting their absorption from food in the intestines, and by promoting re-absorption of calcium in the kidneys."

It is my understanding that parathyroid hormone (PTH) promotes the re-absorption of calcium in the kidneys. Is it is actually vitamin D that does this, or a combination of vitamin D and PTH? If vitamin D is involved, what is the process?

An answer to this question, with a reference to an online medical research or review article, would be appreciated?

Leeirons (talk) 16:42, 11 December 2007 (UTC)[reply]

The reference given (The Merck Manual) states the vitamin D and it metabolites "Enhance Ca reabsorption by the [kidney] tubules". "The conversion to 1,25(OH)2D [active vitamin D hormone] is regulated by its own concentration, parathyroid hormone (PTH), and serum concentrations of Ca and phosphate."--DO11.10 (talk) 18:43, 11 December 2007 (UTC)[reply]

Obesity, hibernation in other mammals. Cross reference to tanning/tanorexia/tanning addiction

Hibernation

"hibernating bears wake up when given vitamin D" looking for confirmation or reliable source/citation for this. http://www.arthritistrust.org/Articles/Sunshine%20Deficiency%20Diseases/index.htm

hibernating bears also have elevated parathyroid hormone which protects against bone loss. http://jeb.biologists.org/cgi/content/abstract/209/9/1630

Morbidly obese humans have decreased vitamin D and elevated PTH. (before and after gastric bypass, so surgery did not cause it). Vitamin D suggested as an additional factor. http://www.springerlink.com/content/c3387p46381j6113/

Anecdotal evidence for euphoric states/elevated/sleep disturbance mood during the summer months at high latitudes.

Vitamin D depletion and correlation with activity/anxiety/nervousness as adaptive behavior - preparation for winter? (might explain some angry bears in the fall and spring!). Looking for citations

Tanning and UV exposure: would be good to reference the 20,000 IU of vitamin produced by 20 minutes of natural UV exposure and whether tanning beds produce this same effect. The human body's vitamin D production is naturally limited to about 20,000 IU/day. After the precursor is used up, no more vitamin D is produced. www.vitamindcouncil.com

216.18.16.98 (talk) 20:21, 17 December 2007 (UTC)johnpaulmorrison@hotmail.com[reply]

are there safety studies/estimates for rotating a UVB light (around the body, locally-applying, in turns) ?

As not a specialist around this field, first, I thought "UV" good for vitaminD could include UVA (blacklight) -- as for tanning. I thought, rotating the body-portions exposed to light, would lessen the skin-age problems associated with (also) UVA.

That UVB is necessary (as this wikipedia article is informing), that heightens the risk of that in-house-D-light plan of mine. Truly? Or, may we keep that in check, such that with UVB lights, could people fortify their bones with light at home? (If sun is good, how is a handheld UVB-light not? Why not talking about that?)

The rotating of the exposure is again a tool to lessen the strain on the skin-spot, probably (unless the skin gets used to that in time). cf. How diabethic people rotate insuline-injections, not to inject at a single spot all the time. What guidelines for amounts of such locally-applying UVB -- in turns? That would fortify this vitD article, I think. --FerzenR (talk) 09:44, 8 January 2008 (UTC)[reply]

Spectral sensitivity and synthesis of previtamin D3

The text summarizing the action of UVB in respect to wavelength segment is far too ambiguous, carries a factual error, and is not representative of actual process involved. It has been understood from experimentation and the resultant literature since the 1980s that optimal synthesis of 7-DHC to preD3 occurs in a relatively narrow band, from 295-300nm, with maximum conversion at 297nm. This segment is often referred to as D-UV.

As such, I am making necessary corrections to the text, and including corroborating references.

Pragmatist (talk) 17:36, 7 February 2008 (UTC)[reply]

"Per glass"

"fortified milk typically provides 100 IU per glass" Is that a big glass or a small glass? perhaps we can create the Big Glass and the Small Glass as a units of measurement specifically for the US, so that we can talk about 2.735642367 Big Glasses of something. 80.2.199.213 (talk) 16:32, 8 March 2008 (UTC)[reply]

Checking the source I see that they meant a one pint glass. --Michael C. Price ^talk 17:49, 8 March 2008 (UTC)[reply]

Role in coronary disease prevention?

There is evidence that vitamin helps hearts, and other evidence that it may raise cholesterol and harm hearts.

The reason may be that there is a window of ideal vitamin D nourishment, and levels below the lower threshold cause coronary problems while levels above the higher threshold tend to raise cholesterol (and harm hearts).

It may be that the cancer-preventing benefits of vitamin D may be maximized, while the possible heart-harming effects are minimized, if one takes three times the chosen dose every third day, with no vitamin D supplementation on the two days in-between.

Perhaps the title to this section lacks nuance, and the section should be re-titled to reflect that the relationship between vitamin D intake and cardiac events may be a bit more complicated than a straight-line correlation between so that higher and higher supplement levels must always result in lower and lower rates of cardiac events. —Preceding unsigned comment added by 68.166.202.4 (talk) 01:51, 21 March 2008 (UTC)[reply]

---

The rising of cholesterol levels could simply be because you're achieving repletion by supplements and not skin cholesterol conversion by UVB. Remember there is still debate about the cholesterol theory, and 'high' cholesterol might simply be an indicator of vitamin D deficiency. i.e. it's not high cholesterol clogging your arteries but lack of a natural anti-inflammatory to control inflammation. —Preceding unsigned comment added by Mo79 (talk • contribs) 10:38, 18 May 2008 (UTC)[reply]

Footnotes format in coronary disease prevention need fixing

Sorry -- added, but can't seem to format.68.166.202.4 (talk) 02:31, 21 March 2008 (UTC)In over my head[reply]

Add section about benefits of vitamin D and fending off and/or fighting influenza

There was a study published which I think successfully explains why the flu is a winter illness, and why vitamin D supplementation in the winter months may help fend off the flu. I've included a link to the paper's abstract below (google scholar):

http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=529704

It would be great to get information from this paper into the wiki article on Vitamin D, and maybe also on the influenza page.... —Preceding unsigned comment added by L8daRa (talk • contribs) 18:12, 17 April 2008 (UTC)[reply]

External links should start with the superb Vitamin D Fact Sheet from the U.S.National Institutes of Health

Vitamin D Fact Sheet from the U.S.National Institutes of Health —Preceding unsigned comment added by 68.165.11.156 (talk) 04:03, 19 May 2008 (UTC)[reply]

Too much D, like too little, a risk factor for breast cancer

http://news.yahoo.com/s/ap/20080516/ap_on_he_me/vitamin_d_breast_cancer;_ylt=A0WTUdfM9TBIGHAB0Q4R.3QA

page not found --Ryan Wise (talk) 13:17, 2 June 2008 (UTC)[reply]

Children can tolerate more Vitamin D, though optimum is debateable

"According to the researchers, due to rapid skeletal growth, children and adolescents are more likely to be vitamin D deficient, and are far less likely to reach vitamin D levels that doctors would consider toxic." [3] Brian Pearson (talk) 22:55, 27 June 2008 (UTC)[reply]

Is D3 supplementation helpful?

I think there's some cause to question whether Vitamin D supplementation is helpful.

There are some who say that low levels of 25 D are caused by infection which causes 25 D to be converted to 1, 25 D in unhealthy amounts due to disregulation of the vitamin D receptor. Testing for 25 D showed lower levels in unhealthy people, but I can't find any controlled study demonstrating that D3 supplementation alone increased bone density superior to either calcium supplementation + D3 or calcium alone.

Likewise, it's anti-cancer effects only appear in short term trials and are comparable with other immunosuppressives such as prednisone in this regard. Benefits disappear with long term use.

see http://bacteriality.com/2007/09/15/vitamind/ and http://trevormarshall.com/BioEssays-Feb08-Marshall-Preprint.pdf —Preceding unsigned comment added by 63.166.226.83 (talk) 18:38, 4 June 2008 (UTC)[reply]

Also;

The ratio of total 25OHD3 and 1,25(OH)2D3 to plasma DBP, rather than total circulating vitamin D metabolites, may provide a more useful index of biological activity. Further studies are required to substantiate this hypothesis. http://www.ncbi.nlm.nih.gov/pubmed/16339300?ordinalpos=33&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum

CONCLUSIONS: Kidney-transplant recipients receiving modern immunosuppressive regimens with low doses of corticosteroids experience only minimal loss of BMD during the first posttransplant year. Cholecalciferol supplementation did not prevent posttransplant bone loss http://www.ncbi.nlm.nih.gov/pubmed/15714177?ordinalpos=45&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum --Ryan Wise (talk) 13:10, 2 June 2008 (UTC)[reply]

In the article, it said, "In one study, hypercalciuria and bone loss occurred in four patients with documented vitamin D toxicity." Could 25,000 IU have actually caused some demineralization? Brian Pearson (talk) 03:42, 3 June 2008 (UTC)[reply]

It should, yes. Especially in such high doses. --Ryan Wise (talk) 18:21, 13 June 2008 (UTC)[reply]

Re Reference #54

It [4] mentions COMA -- Committee on Medical Aspects of Food and Nutrition Policy (UK; disbanded in 2000). It had recommended, "...For individuals confined indoors, pregnant and lactating women, an intake of 0.01 mg/day..." I think this is a bit outdated. It's my understanding 2000 IU is more appropriate. Brian Pearson (talk) 22:54, 27 June 2008 (UTC)[reply]

An explaination for the French paradox

See http://www.thelancet.com/journals/lancet/article/PIIS014067360668971X/abstract http://sci.tech-archive.net/Archive/sci.med.nutrition/2007-09/msg00331.html Incidently, took mild vit d pills last winter - no colds at all. 80.2.194.251 (talk) 15:53, 28 June 2008 (UTC)[reply]