Vitamin D (UVB) experiment and lamp comparison
I decided to look into vitamin D / UVB lamps after receiving a blood test with low vitamin D levels in spite of supplementation (learn how I tested my levels). I expected there'd be a few standard, affordable solutions, but was surprised at both the cost and complexity of comparing different options. I compared the products below and tried several experiments using Exo Terra's reptile bulbs for frugality's sake.
Experiment results
I was surprised at how intense the treatments needed to be to budge my vitamin D levels.
Each of the experiments below was performed for about a month.
Experiments that failed to raise my levels
- 30 minutes daily with a single Exo Terra Repti Glo 10.0 on bare skin from an ~18 inch distance.
- 2 hours and 30 minutes daily with a single Exo Terra UVB200 bulb on bare skin from an ~10-12 inch distance.
- 1 hour and 30 minutes daily with 3 Exo Terra UVB200 bulbs in reflective fixtures on bare skin (front and back) from a ~12 inch distance.
The experiment that finally worked for me
I used 3 Exo Terra UVB200 bulbs as close as I could practically get them to my body for 90 minutes daily. I bought them off eBay because they seem to be the cheapest source. However, buying from random sellers makes me a little concerned about quality / counterfeiting issues, especially on a product that already carries some risk.
For the back of my body, I'd modified an existing lighting fixture with a high tech reflective technology called aluminum foil. I positioned this about 7 inches away from my back so that very little of the light went to "waste." 
For the front of my body, I bought an Exo Terra 7" Deep Dome fixture from Amazon. I positioned it 12 inches from my chest. I was unable to move it any closer because of my desk setup. I also tried the 5.5 inch model, but it was a little too shallow to direct all of the light. 
I used cheapo UV safety glasses from the hardware store. They turned out to look wonderfully ridiculous.
I let the bulbs warm up for 5-10 minutes before use because I think their spectrum changes in the beginning.
My bloodwork suggests this regimen raises my vitamin D by ~2ng/mL per 30 days, and that's with my very pale skin. That isn't anything amazing, but it seems like it'll be a good way of managing my levels if I decide to accept the risks of the UV exposure.
After seeing how many bulbs were required to raise my levels, I'm not sure my approach of trying to save money by using reptile bulbs makes sense. I spent about $80 total, which isn't much cheaper than something like the RayMinder 1 below.
Safety issues
There are definitely risks to this kind of UV exposure, and I'm definitely not suggesting anyone try it. I tried to mitigate any damage with the tools below, but I'm unsure about whether I'll continue the sessions long term:
- I use UV safety glasses.
- I apply Solban beforehand in hopes of minimizing skin damage.
- I use my red light setup at the same time in hopes of it providing a protective effect.
Why not just increase supplement dosage?
I suspect there are benefits to the process of your body creating its own vitamin D that aren't captured in supplements. However, I will probably return to using supplements for some or all of my vitamin D after seeing the intense sessions required.
Would SAD lamps have helped?
SAD lamps are legally required to have no UV output, so they can't be used for this purpose.
Products I looked at
Least-expensive products
There are several reptile bulbs that are probably good at creating vitamin D. They're inexpensive, work in standard fixtures, and have a nice peak around 311nm in the spectrum. However, they have some downsides:
- More UVA than the more-expensive products (but, as best I can tell, much less ratio-wise than the sun).
- Less output than the higher-end products (likely requiring several bulbs, or at least appeared to in my case).
I chose Exo Terra's UVB200 bulbs for my experiments because of their intensity and low cost. I'm unsure about their safety, however.
Moderate-priced products
Moving up into the few-hundred-dollar price range, the RayMinder Model 1 looks like a good option to me: it's relatively inexpensive and provides spectrum data. The Model 2 looks even better, but doesn't seem to be available right now.
High-end products
The more-expensive (several hundred to several thousand dollar price range) options all look good to me. I imagine they'd be particularly useful to people that want to get their daily UVB dose quickly with an absolute minimum of UVA.
Product data
Here are all of the products I looked at if you'd like to compare them for your own purposes:
| Product | Approximate cost | Output / notes |
|---|---|---|
 | $13+ | 14, 15, 20, 25, 30, and 40 watt bulbs available. Very little UVB relatively speaking. Requires a fixture.  |
 | $14+ | 14, 15, 20, 25, 30, and 40 watt bulbs available. More UVB than the 2.0. Requires a fixture.  |
 | $15+ | 14, 15, 20, 25, 30, and 40 watt bulbs available. More UVB than the 5.0. Requires a fixture.  |
 | $30+ | 80, 125, and 160 watt bulbs available.  |
 | $31+ | 35, 50, and 70 watt bulbs available. Requires a fixture.  |
 | $26 | 13 watts. Requires a fixture.  |
 | $13 | 13 and 26 watt bulbs available. Works in ordinary light fixtures.  |
 | $15 | 13 and 26 watt bulbs available. Works in ordinary light fixtures.  |
 | $24 | 13 and 26 watt bulbs available. Works in ordinary light fixtures.  |
 | $29+ | 100 and 160 watt bulbs available. Works in ordinary light fixtures. The writer at Vitamin D Wiki estimates his 160 watt bulb with a reflector has about 10% of the UVB he gets from summer noontime Seattle sun. |
 Light Years 2 B2R (discontinued?) | $236 | Unknown output. Available only with UVB bulbs. |
 Light Years 2 S18 (discontinued?) | $134 | Unknown output. Available with UVB or UVC bulbs. |
 Light Years 2 S18 Flex (discontinued?) | $224 | Unknown output. Available with UVB or UVC bulbs. |
 Light Years 2 S36 (discontinued?) | $149 | Unknown output, but UVC bulbs. |
 Light Years 2 S72 (discontinued?) | $256 | Unknown output, but UVC bulbs. |
 | $1,000 | 311nm narrowband, 18 watts UV. Prescription required. |
 | $7,000 | 311nm narrowband. 1600 watts UV. Prescription required. |
 | $2,000 | Narrowband, 144 watts UV. Prescription required. |
 | $4,900 | Choice of UVA or 311nm UVB narrowband. 1000 watts UV. Prescription required. |
 | $2,600+ | Choice of UVA, UVB, or 311nm UVB narrowband. 600 watts UV. Prescription required. |
 | $150 |  |
 | Unknown |  |
 | $800+ | Choice of UVB narrow or broadband. Handheld |
 | $1200+ | UVB narrowband. "hand/foot & spot", but big enough for torso |
 | $1800+ | Choice of UVB narrow or broadband. Full body. Looks like something you'd find on a space ship, so that's pretty cool. |
 | $1200+ | Choice of UVB narrow or broadband Very large full-body system, expandable. Prescription required? |
 | $389 | Unknown output. Prescription required. |
 | $425 | Unknown output. No prescription required. |
 | $28+ | 13 watts (mini CFL) or 26 watts (regular CFL) with a claimed 10% UVB, 30% UVA. Works in ordinary light fixtures.  |
 | $28+ | 15, 17, 24, 25, 32, 39, and 54 watt bulbs available. Requires a T5/T8 fixture.  |
 | $11+ | 13 and 26 watt bulbs available with a claimed 5% UVB, 30% UVA. Works in ordinary light fixtures.  |
 | $22+ | 14, 15, 17, 24, 25, 32, 39 watt bulbs available. Requires a T5/T8 fixture.  |
Other vitamin D info
- UVB benefits on SelfHacked.
- Free vitamin D self-test (I'm unsure how valid this test is, but it's easy, and interesting to try).
- Reptile light and Light Years 2 / Sperti lamp discussion from Vitamin D Wiki.