Since moving to Seattle a few years ago, I'm wondering if I get vitamin D deficiency during the dark rainy months of the year. There are available light boxes that are used for treated seasonal affective disorder. I’m wondering if these are also effective to prevent vitamin D deficiency when there is inadequate natural UV exposure.

Are artificial lamps able to substitute for natural sunlight to produce vitamin D in the skin? Or can this be replaced effectively by oral supplementation?

  • Welcome to Health SE. I'm afraid that this question is off-topic, because it is asking for a recommendation, not about the topic of health as defined in the help center. I'm going to have to vote to close this.
    – michaelpri
    Sep 13, 2015 at 21:48
  • 1
    Hi Dan, I made some edits to make this on topic. Please feel free to adjust as you see fit if this doesn’t cover what you were intending, but note that asking for product recommendations is off topic, as michaelpri pointed out.
    – Susan
    Sep 14, 2015 at 1:30

1 Answer 1


Only two things affect the synthesis of vitamin D, and those are the amount of UVB photons penetrating the skin and the person's age. See my previous answer for an explanation and citations.

So if we disregard age the only question becomes do light boxes supply adequate UVB to synthesize adequate vitamin D? From what I can tell from a review of the products out there, the answer is probably not. Lights adequate to treat SAD aren't adequate to generate vitamin D, and a light that supplied adequate UVB would be dangerous if misused.

But in my mind the final nail in the coffin for light therapy is this study:

All subjects receiving vitamin D improved in all outcome measures. The phototherapy group showed no significant change in depression scale measures. Vitamin D status improved in both groups (74% vitamin D group, p < 0.005 and 36% phototherapy group, p < 0.01).

In short, although phototherapy improved vitamin D levels, it did so only half as well as supplements, and unlike supplements it had no effect on depression.

  • There are many studies which show efficacy of light therapy for SAD (here's one from around the time of your own paper.) In general, it is relatively easy to find one study to support a sweeping conclusion. While some studies may question the benefit of light therapy, you still can't make broad generalizations like "I can't imagine why anyone would choose phototherapy instead." That wasn't really the OP's question, either. Sep 14, 2015 at 15:17
  • then maybe you should expand on your assertion. Sep 15, 2015 at 4:46
  • @anongoodnurse The question is vitamin D production and I think the science of my first link suffices. Can you expose yourself to enough artificial UVB to produce sufficient vitamin D? Oh, I'm sure you can, but I don't know why anyone would.
    – Carey Gregory
    Sep 15, 2015 at 5:53
  • @CareyGregory would you consider it a duplicate to ask about the effect of tanning beds vs. sunlight as it pertains to vitamin D levels? Jul 28, 2018 at 15:53

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