Mem had mentioned that sunlight would help make vitamin D. Getting more sun exposure isn’t really practical, so I put that in the “interesting, but not useful” file.
I’m taking 6000 IU/day of vitamin D supplements, spread across four doses. That brought me up from “seriously deficient” to “just barely in the acceptable range.” I don’t think uptake on D supplements is all that good, and I haven’t found any papers on dose vs. improvements in D level, which makes me suspect there’s an upper limit on how much they can help.
The other day I followed up on Mem’s comment some more. I found a paper on what wavelength is most effective for vitamin D production. It’s right in the middle of the UVB range. UVA is just below visible light, used for things like drying fingernail polish and lighting velvet Elvis paintings. UVC is further up in the ultraviolet, and is used for disinfecting things. UVB is, of course, smack in the middle, but there’s not a lot of UVB lighting out there. I found some UVB LEDs of the proper wavelength, but they were $40 *each*. I found some curly-flourescent UVB light bulbs, and then odd-length straight flourescents.
Further reading showed that most of them, even if rated as “UVB”, only put out 3% to 7% UBV; the rest is UVA. However, the paper that showed D production by wavelength showed that though much less efficient, UVA still makes a bit, and the since ~95% of the lamp output is UVA, there’s plenty of it.
I didn’t get a whole lot more from the medical searches, but then I hit a bonanza on herpetology sites. The snake, lizard, turtle, and spider guys are heavy into UVB, which their pets need. It’s a larger market than medical, and some of those guys are engineer types who test things with UV meters and kill-a-watts.
I finally ordered a pair of 34” UVB lamps and some UV goggles. The D home test kits are $50 each.
“What could possibly go wrong?”