Sunlight is Your Friend →

Here is the key passage, as a statistical example:

We thought vitamin D was going to be a magic pill, because people who naturally have high levels of vitamin D in their blood from sun exposure have lower rates of every disease. We began supplementing with vitamin D to tens of millions of Americans — and all the big clinical trials showed essentially no impact from that supplementation. It didn’t improve a single condition (unless you had extremely low levels of vitamin D to begin with). 

Vitamin D through a pill doesn’t deliver the benefits of vitamin D through the skin, and everyone’s still trying to figure out why. Maybe vitamin D was just a marker for sunlight, and it was actually other benefits of sun exposure that were responsible for some of those benefits. Or maybe vitamin D is just one of many related compounds (we now know) made in the skin through different combinations of sunlight and enzymes, all of which seem to be anti-inflammatory, anti-carcinogenic, full of antioxidants. If you take a pill, you only get one vitamin, while if you are getting sunlight on your skin, you’re getting a couple dozen of these compounds. I think that’s probably part of the answer, but the research is still early.