paper-machine comments on Announcing the Quantified Health Prize - Less Wrong

50 Post author: Zvi 02 December 2011 06:01AM

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Comment author: [deleted] 08 December 2011 04:35:39AM 5 points [-]

The link you sent me did not disprove my theory

See this part, emphasis mine.

Vitamin D3 is made in the skin when 7-dehydrocholesterol reacts with ultraviolet light (UVB) at wavelengths between 270 and 300 nm, with peak synthesis occurring between 295 and 297 nm. These wavelengths are present in sunlight when the UV index is greater than three, as well as in the light emitted by the UV lamps in tanning beds (which produce ultraviolet primarily in the UVA spectrum, but typically produce 4% to 10% of the total UV emissions as UVB).

UV lamps in tanning beds produce UV light of the right frequency to stimulate vitamin D production. They have to, in order to do what they do.

and please don't reference wikipedia. I know you can do much better.

A trivial Googling shows several sources claiming that tanning beds and lamps generate UVB.

The problem is that nobody really knows exactly what rays humans need to make vitamin D.

UVB light. See above.

Also, can you find a single large-scale (I would say 1000+, but that's a relatively low number. A real large scale study is more like 10,000+...) study that shows lamps produce significant amounts of V.D.?

Reasonably large studies have been done on treating rickets, a vitamin D deficiency, with ultraviolet lamps. Unsurprisingly, it works.

Now then, what evidence do you have that 1) we don't know what wavelengths of light stimulate vitamin D production; 2) we can't build lamps that produce those wavelengths; and 3) that the lamps we have do more harm than good.

Consider 3) in the light of the vast advances in curing rickets since the 19th century.