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Information on the latest vitamin D news and research.

Find out more information on deficiency, supplementation, sun exposure, and how vitamin D relates to your health.

Where is our vitamin D coming from: Part 2

As we know from the previous blog, Professor Robert Heaney found that 1,600 IU of vitamin D/day input source is missing from modern man. What I mean by that, is somehow 25(OH)D levels of modern man reflect that humans are getting an extra 1600 IU of vitamin D that is not coming from sun exposure or the cholecalciferol in food. The question has arose, might there be 25(OH)D in meat that accounts for the equivalent of 1600 IU of vitamin D?

There is a study that measured the 25(OH)D levels of meat eaters and vegans. It found meat eaters had the highest mean plasma 25(OH)D (around 30 ng/ml) and vegans lower (around 22 ng/ml). It also found that dietary intake of vitamin D3 could only explain a little of the difference in 25(OH)D levels between meat eaters and vegans.

Crowe FL, Steur M, Allen NE, Appleby PN, Travis RC, Key TJ. Plasma concentrations of 25-hydroxyvitamin D in meat eaters, fish eaters, vegetarians and vegans: results from the EPIC-Oxford study. Public Health Nutr. 2011 Feb;14(2):340-6.

This may mean that meat contains another form of vitamin D, probably 25(OH)D. Feed lots for beef are usually outdoors. In the summer, cattle must get significant vitamin D, and their meat may contain 25(OH)D. Other animals, such as hogs and chickens, while usually raised indoors, may have significant quantities of vitamin D added to their food. So in theory, meat may contain significant quantities of 25(OH)D.

However, in a review of the 25(OH)D content of foods back in 2003, Doctor Lars Ovesen and colleagues of the Danish Food Administration found little 25(OH)D in meat.

Ovesen L, Brot C, Jakobsen J. Food contents and biological activity of 25-hydroxyvitamin D: a vitamin D metabolite to be reckoned with? Ann Nutr Metab. 2003;47(3-4):107-13. Review.

The wrote,

“From the few systematic studies which have been performed the food contents of 25OHD in animal foods are usually low but vary. Contents are typically very low in milk and fish (<0.1 ug/100 g), somewhat higher in meat (0.2–0.4 ug/100 g) and up to 1 ug/100 g in egg yolk.”

Even if you use the highest amount found it meat (0.4 ug/100 g) and assume 25(OH)D is six times as potent as D3, this only amounts to about 100 IU of D3 in every 100 grams of meat. So, according to what we now know, 25(OH)D in meat cannot account for much of the missing 1,600 IU that Professor Heaney found.

Where does the extra 1,600 IU/day come from?

I don’t know. Perhaps it comes from light other than UVB triggering D3 production in the skin. Most people do not know that UVC (a shorter and highly carcingenic wavelength of light) is more potent than UVB in making D3 in the skin.

Several studies from 70 years ago indicate that UVC (which, luckily does not get through the atmosphere) is highly effective in both producing vitamin D and in treating rachitic rats.

Bunker JWM, Harris RS, Mosher LM: Relative efficiency of active wave-lengths of ultraviolet in activation of 7-dehydrocholesterol. J Am Chem Soc 1940, 62(3):508-511.

In 1938, Knudson and Benford studied numerous UV wavelengths in rats, finding that shorter UVC is as effective as any of the longer UVB wavelengths studied in curing rickets.

Knudson A, Benford F: Quantitative studies of the effectiveness of ultraviolet radiation of various wavelengths in rickets. J Biol Chem 1938, 124:287-299.

Professor Michael Holick’s lab confirmed that UVC makes vitamin D. Per photon, UVC was more effective than UVB in making vitamin D. However, we must remember that UVC is highly carcinogenic.

MacLaughlin JA, Anderson RR, Holick MF: Spectral character of sunlight modulates photosynthesis of previtamin D3 and its photoisomers in human skin. Science 1982, 216(4549):1001-1003.

What about even shorter wavelengths of light? Will wavelengths shorter than UVC trigger photo-isomerization of vitamin D in the skin? If UVC can do it, what about even shorter wavelengths such as x-rays? X-rays come from space all the time; you are constantly bombarded with X-rays. The shorter the wavelength, the more energy it has. Maybe some shorter wavelengths can photo-isomerize vitamin D?

What about radioluminescence? It is a phenomenon by a material makes photons by bombarding it with ionizing radiation. Does ionizing radiation, such as that emitted by radon gas, strike a material in the skin, such as the heme molecule, (as in hemoglobin), and then does the heme molecule emit UVB or UVC in the skin?

Does that explain the missing 1,600 IU/day? If my theory were true, one would think animal studies would have detected it. As far as I know, rats kept inside and not given vitamin D have undetectable blood levels of 25(OH)D. Is that true? Perhaps rats and humans have different vitamin D skin systems.

Readers, I need some help here. I am a psychiatrist, not a physicist. If you know that shorter wavelengths cannot do it, I would appreciate the reference or the law of physics that prohibits photo-isomerization by wavelengths shorter than UVC. Where does that missing 1,600 IU/day come from?

  About: John Cannell, MD

Dr. John Cannell is founder of the Vitamin D Council. He has written many peer-reviewed papers on vitamin D and speaks frequently across the United States on the subject. Dr. Cannell holds an M.D. and has served the medical field as a general practitioner, emergency physician, and psychiatrist.

One Response to Where is our vitamin D coming from: Part 2

  1. WHat about 254 nM UVc from fluorescent lights? In spite of having a thin glass envelope, how much escapes from the ends of the bulbs where there may be less phosphor? From the active region of the bulb?