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Bold textDead links:

• http://www.orst.edu/dept/lpi/infocenter/vitamins/vitaminD/index.html
• http://www.innvista.com/health/healvitd.htm

--Menchi 23:02 15 Jul 2003 (UTC)

I have a problem with the statement that light skinned people evolved in the northern latitudes because they could make vd3 better than dark skinned people.

One story goes that the relationship between rickets and sunlight was made when poor children, living in narrow, sunless streets in the London were exposed to more sunlight and didn't get rickets. This may be a true story, but to equate the evolution of light skinned people to the production of vd3 in cloudy regions is more than a stretch, in my opinion.

I going to take this statement out, but if someone can respond with some quantitative study showing that this is a valid scientific concept, we can put it back in. Its just not a very scientific statement.

srlasky 03:09, 2005 Apr 25 (UTC)

Cleanup Request

I would flag this article for cleanup, but I am unsure which cleanup tag to use. At the current point in time, the article is missing critical information in various sections, and as such, is troublesome to understand. If you read through the overview, you should understand what I mean. So, yeah. If someone with a little more experience at this than me put the right cleanup tag on the article, that would be great. LuNatic 03:40, 8 June 2006 (UTC)

Natural source of vitamine D

Does anybody know if there is an easily eatable natural source of vitamine D without huge amount of vitamine A inside the same package ?

I doubt this information

Although I am not an expert, I have problems with this bit:

Oral overdose of vitamin D3

Overdose is extremely rare whilst mild deficiencies are very common.

For overdose to occur chronic doses of 100x the standard RDA each day, over many months is normally required. The RDA itself is in fact more than 200x less than the amount that may be generated in even a few minutes of midday sunshine. But whilst the sunshine generated quantity is self-limiting, vitamin pills are not and this has led to widespread concern, which may have been very much misplaced.

In practice, all common foods and correctly formulated vitamin pills essentially contain far too little for overdose to ever occur in normal circumstances. Indeed, Stoss therapy involves taking a dose over a thousand times the daily RDA once every few months and even then often fails to normalise vitamin D3 levels in the body.

However, oral overdose has been recorded due to manufacturing and industrial accidents and leads to hypercalcemia and atheroschlerosis, so overdose is very definitely possible.

"100x" and "200x" are very arbitrary numbers, and I have problems even with the x's. I guess "times" would be more professional, and There is no specified amount in weight, which I think is more scientifically sound. In addition, the details are very arbitrary yet extreme, refering to "amount generated in a few minutes of sunshine" and such.blueaster

The world is not clear-cut- vitamin D production varies with age, skin colour etc.WolfKeeper

In addition, the article suggests that even with supplements and treatment, people can still lack vitamin D while I remember a News Magazine article stating that people should avoid vitamin D supplements while sunlight and foods should be a sufficient source.blueaster

I've checked the nutritional breakdown of foods. Most foods contain no vitamin D. A very few, like eggs contain 20%. It's nearly impossible to get the RDA from unsupplemented food alone. (Oily fish is about the only really good source). And the RDA will eventually leave you deficient. Sunlight depends on latitude and exposure at the right time (n.b. ~20% of Indians - in India - are borderline deficient).WolfKeeper

To be honest, I think scientists don't know what the optimum intake of vitamin D is. There is a reasonable argument that says that the RDA is too low. The argument that says it is too high, or unnecessary seems quite weak. As I understand it, it's looking at the moment like the RDA will increase.WolfKeeper

Also, from basic nutritional knowledge, I know that as vitamin D is a fat-soluble vitamin, it can be stored for periods and does not have to be consumed as often as water-soluble ones (not K, A, D, or E).blueaster

That's quite true. But the potential storage is *massive* compared to the daily RDA; and there seem to be chemical reactions that control the level provided you aren't taking more than 200x the RDA or so.WolfKeeper

In addition, I distinctly remember reading in my chemistry textbook that a group of scientists killed and ate a polar bear during a trip and they all came down with vitamin D poisoning, as the liver of a polar bear contains about 1300 times the recomended daily amount of vitamin D. blueaster

No, deaths and illnesses from polar bear liver are due to vitamin A. Vitamin A is unquestionably more toxic- even the RDA isn't much less than the amount needed to max out the liver stores, and the excess is very definitely toxic. There's even evidence that sub-rda amounts of vitamin A cause osteoporosis. Vitamin A is very scary. I've been on Accutane, so I know about vitamin A toxicity first hand. WolfKeeper

So this claim with a treatment with recieving 1000 times RDA seems ridiculous. And I do not understand how it is plausible for any accident to end in oral consumption of vitamin D during manufacture.I could think up of a slap-stick scene that results in this, but not anything that would happen in real life.

The article does say that overdose is very rare. There has been a case of incorrectly formulated vitamin pills where they had 1000x the correct dose. WolfKeeper

I highly suspect that this part of the article is biased and has been written by either a misinformed person who is not an expert (although I am not an expert either), or a person in whose business interests are involved with the sale of vitamin D supplements. WE NEED AN EXPERT TO EVALUATE THIS RIGHT NOW!!!. And I do not know why it is called "D3". blueaster

Just for the record, I wrote the bit you have criticised. I don't have any financial involvement in any vitamin D production, sale or anything else. So far as I can tell, vitamin D toxicity essentially never happens. It all looks like a big mess up. Vitamin D toxicity involves taking an entire bottle of tablets everyday for months, and you can't get it from food. Vitamin A toxicity- you can get that by eating a not-ridiculous amount of liver or a few tablets a day. If you can find any information that contradicts what I have written, please point us to it, I'd love for a bit more balance in this article if there's any to be found.WolfKeeper

Vitamin D toxicity can and did happen. It causes metastatic soft tissue calcification. It can be fatal. In the heydey of vitamin D supplementation, earlier in the last century, many cases of toxicity and even death were recorded. (See: Bicknell and Prescott: The Vitamins in Medicine, 3rd Ed., 1952 -- great reviews of vitamin therapy up to that date.) Vitamin D in doses of 100-150,000 IUs per day were used in the treatment of several diseases, including tuberculosis, lupus and autoimmune diseases. This treatment was often successful, but such vitamin D doses are on the verge of the toxic, and some subjects did succumb to poisoning. Today, vitamin D poisoning is rare, mostly because the high-potency preparations that were available at that time are not now available. Given the current vitamin D mania (haha), high-potency preps will probably become available once again, and toxicity cases will be reported. Still in all vitamin D deficiency is unquestionably much more important as a public health issue than vitamin D intoxication ever was, or ever will be. --AEL

By the way, the vitamin A phobia is a bit much, here. Vitamin A can be toxic, like vitamin D, but you have to take a whole hell of a lot of it. Also, there is old evidence (see, again, The Vitamins in Medicine, vitamin D monograph) as well as new evidence, that vitamins A and D are complementary or even synergistic in important ways, and that they should probably always be used together -- just as they often occur in nature. For example (back to The Vitamins in Medicine), it seems that supplementary vitamin A protects against vitamin D intoxication, at least in animals (no human clinical work is available, AFAIK). At the same time, from more modern literature it appears that vitamin A inhibits the enzyme that degrades vitamin D (medline # 16289102), thereby extending the active life of vitamin D. There is also evidence (pre-clinical) that the combination of vitamins A and D have anti-cancer effects beyond that of either vitamin alone. (And recall that vitamin A is an anti-cancer vitamin, also.) But, you might ask, how could vitamin A protect against vitamin D intoxication while also being "pro- vitamin-D", biochemically? I don't know the answer, but my guess is that it is a matter of dose and circumstance. Often, what occurs at one dose can be reversed at a much higher dose, or under different conditions. Vitamin A might have a "pro-vitamin-D" effect at physiologic levels, but then reverse itself and act, effectively, as an anti-vitamin-D at higher levels or under the circumstance of vitamin D intoxication. I expect that vitamin A will indeed protect against vitamin D intoxication in humans -- at least in humans who are smart enough to take the two (naturally associated) vitamins together, rather than mega-dosing with them separately. I also expect that vitamin D will protect against vitamin A intoxication. Just eyeballing the thing, that would seem a no-brainer, since vitamin D has actions on calcium metabolism roughly the opposite of vitamin A. Bottom line: take vitamin A and D as they come in granny's old-fashioned cod liver oil! For the most part, forget isolated vitamin D, isolated omega-3s, etc. Use the whole food for multiple benefits AND protection against any possible untoward effects. Use isolated vitamin D in modest amounts, perhaps for the winter months, if you live in a northern clime and/or if you have a lot of melanin (i.e. if you're black). But whatever you do, keep up with the cod liver oil. --AEL [who owns no stock in cod liver oil companies. :-) ]

Is vitamin D truly a "vitamin"?

The current (Aug 14, 2005) version of the entry about vitamin D starts off with the implication that it is improperly referred to as a vitamin. I have a problem with this. Originally, vitamins were identified and measured based on their "bioactivity", their efficacy in animal models. The discovery of vitamins surely owes much to the rickets that resulted when animals were housed away from natural light sources, in rooms lit by the incandescent light bulb. The rickets that ensued in laboratory rats could be cured by adding some cod liver oil to their diets. The result was the discovery of the accessory food factor, antirachitic A.

Casimir Funk's 1912 book (in German, translated to English in 1922) refers repeatedly to vitamine A (the first "vitamin") as "antirachitic A". (cited in Misplaced Pages under "vitamin"). I emphasize that what was originally called vitamin A had antirachitic bioactivity; i.e. the first vitamin was what we now call vitamin D.

Why are we now even thinking of the question whether vitamin D, with its antirachitic bioactivity, is or is not truly a "vitamin"? It is a debate that hinges on the misconception that a vitamin is something that must only be available through the diet. That concept is a misunderstanding. Indeed, vitamin D is truly a vitamin in every sense of the word.

Probably the best way to think of vitamin D (cholecalciferol) is as "the sunshine vitamin". What we need to consume orally, as for the rats in their dimly lit rooms of long ago, should be designed to replace what we are not getting from sunshine.

The real debate should be whether vitamin D2 is truly a vitamin. That molecule is not naturally present in primates, and it has different bioactivity potency than cholecalciferol. Furthermore, should the many "vitamin D analogs" being developed by the pharmaceutical industry to mimic the hormone derived from the vitamin D molecule be called, vitamin D? I would argue that these compounds that relate to pharmacology should never ever be called "vitamin".

This debate has gone on for years. For a supposedly authoratative paper that deserves much revision because it is wrong in its definition of vitamin D, the reader may wish to go to the IUPAC website IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN) Nomenclature of Vitamin D Recommendations 1981 at the following address:

http://www.chem.qmul.ac.uk/iupac/misc/D.html

"Irridated"?

...what's this about D5 being also known as "irridated 7-dehydrositosterol"? Is that supposed to be "irradiated", perhaps? Does anyone have any clue as to what this means? Google shows "irridate" and "irridation" being used only as misspellings for "irradiate" and "irradiation", and "irridated" is only found in Wikimirrors of this very article - but giving the formal name of a substance as "irradiated (whatever)" doesn't make any sense.

Normally, I'd consider it to be just tiny gibberish-vandalism, and snip it out wholesale, but the fact that it was contributed by a registered user with a substantial edit history who continued making reasonable edits afterwards... I dunno.

I'm going to be bold and snip it out, but I left him a (slightly more detailed) message on his talk page about this, and if anyone else knows what the hell it means, could you explain? Thanks. DS 14:23, 14 September 2005 (UTC)

Yeah, AFAIK they produce it by exposing fat bearing products to UV (i.e. irradiated with UV); and the vitamin D gets created automagically (or some such thing). That's how the fortification works. So you snipped out correct info. Congrats.WolfKeeper 12:23, 28 August 2006 (UTC)

gasp

From typing in some ingredients from my calcium/vit D supplement into google, I have found:

vitamin D is more of a horomone, not a vitamin

and we make more than enough vitamin D with 20 minutes of sunshine a day, but taking supplements risks overdose (we obviously wouldnt produce it ourselves to the point of poisoning, however)

It's not true *most* of the year in *most* of Europe for example. Between summer exposures you're running on stores which gradually deplete. The stores are large, but studies have shown that say more than 10% of people in even very sunny climates (India!) are clinically deficient at any one time. That's not good! From the figures I've seen, the risks of overdose from pills provided you don't take absolutely ridiculous numbers of pills is, quite frankly, zero. I suppose if you lived in Hawaii, went out in the midday sun for 20 minutes everyday, AND took handfulls of pills, maybe you might, eventually hit overdose. But probably skin cancer would get you first.WolfKeeper 08:39, 23 September 2005 (UTC)

i will have to either find many sites that say this, or find a scientific journal piece that verifies this, but how come I dont remember reading this information on this article?

btw, i googled Cholecalciferol to get the sites. Blueaster 02:27, 23 September 2005 (UTC)

Correction needed in refrence to Breastfeeding and Vit D deficenciey

The following refrences show that if the Mother has sufficent amounts of Vitamin D it will be passed on the the child.

American Journal of Clinical Nutrition, Vol. 79, No. 5, 717-726, May 2004. Other references can be found by searching Sunlight Deficiency, Vitamin D, and Breastfeeding by AMMAWELL since Im new at this I will correct the info when I figure it out Smilesalot2u 01:15, 1 December 2005 (UTC)

Citation needed

I find this statement to be dubious: "For example, in the United States, those living north of a line from San Francisco to Atlanta will not be able to produce it at all for 3 to 6 months a year." If it is true, I think it needs a citation. Plus San Francisco and Atlanta differ greatly in latitude. It makes no sense to use a line that is not even close to being parallel to a latitude line.

Of course, you never lose the ability to produce vitamin D. It is all a matter of how much, given the limited sun exposure at certain latitudes, and given typical (indoors, lots of clothes) lifestyles. --AEL

Correction of RDA figure needed

Hmm, here in America anyway, 200 I.U. equates to 50% RDA. 400 I.U. is, according to at least three of the supplements I have, in fact 100% RDA of Vitamin D. I would request the figures be corrected to correspond with reality, if no one objects. Please, folks, are my pill bottles lying or is the info on this particular Wiki article incorrect/outmoded? Is 100% RDA of Vitamin D 200 I.U. or 400 I.U.?

In the UK I have pills marked: 10 micrograms, 400 IU 'EC RDA 200%'. And another marked: 7.5 micrograms 300 IU, RDA 150%WolfKeeper 02:39, 2 February 2006 (UTC)

See they have different RDAs for different age groups. Maybe your pills are for seniors???WolfKeeper 02:42, 2 February 2006 (UTC)

Steroid?

The following link says that it's a steroid. WolfKeeper 20:54, 2 April 2006 (UTC)

Many people (physicians, physiologists, university professors) make the mistake of saying that vitamin D is a steroid. This is probably because (like steroids) it is derived from cholesterol and has carbon backbone that resembles the steroid backbone. Nevertheless, all steroids have four fused rings. Vitamin D does not have four fused rings, hence it is not a steroid. --David Iberri (talk) 20:58, 2 April 2006 (UTC)

In reality, Vitamin D is a seco-sterol molecule. But since its derived from 7 dehydro-cholesterol, people say that it is a steroid hormone. seco-sterol is the correct term and should be in the article (so I will put it there next to fat soluble). srlasky 17:32, 25 April 2006 (UTC)

I've also encountered the term lysosteroid and used it in a related article (though I can't immediately recall which one) a while back. I'll see if I can dig that up when I have a moment. --David Iberri (talk) 04:46, 26 April 2006 (UTC)

Apparently no one else has heard of lysosteroid, as googling returns a single page—the one I recently edited (Cholecalciferol). :-( So I've changed it to secosteroid, which is in very wide use. Now I'm off to complain to my biochem professor for using lysosteroid to begin with... Thanks for clearing this up, srlasky. --David Iberri (talk) 16:24, 28 April 2006 (UTC)

Units of measure

How much is "3.5 oz."? The article ounce gives two different units of mass (avoirdupois ounce = 28.35 g and troy ounce = 31.1025 g) and two different units of volume(28.41 ml and 29.57ml).

How much is "1 tablespoon"?

Analogues like the KH 1060

I see that the Vitamin D analogues redirect to here. But recent developpements of analogues like the KH 1060 are considerable enought to brake the redirect, at least an article for those analogues now used as potent inhibitors of proliferation in studies. Fad (ix) 00:17, 11 July 2006 (UTC)

Evolution of human skin color

"Melanin screens UVB light so dark skin is much less efficient at generating vitamin D. It would therefore be expected that people with darker 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)

References Deleted:

I deleted the reference section. Please put the references back.

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