Vitamin D is an interesting chemical. The “vitamin” name is deceiving… vitamin D is a hormone that is associated with all sort of things including immunity, cancer protection and surveillance, and neuronal regeneration and repair. We make most of it in our skin, but in recent years we’ve been told to avoid the sun altogether to prevent skin cancer. Low levels are associated with all sorts of bad things from osteoporosis to schizophrenia. But that’s not the entire story. Vitamin D (as we measure it, which is in the form of 25-hydroxy vitamin D) tends to fall with levels of inflammation. So I’ve had some patients with SHOCKING vitamin D levels… like “4” or “6” when we are really looking for 30-50 as a nice range. We don’t know whether the low levels are cause or effect (or a little of both) but we do know that enough vitamin D is essential for bone and brain health, so I do recommend some judicious supplementation if levels are questionable.
So in the military study, soldiers who had killed themselves were compared to other soldiers matched for age and health, and it was found that overall vitamin D levels were pretty comparable between the two groups, with an average level of around 24.5. Samples were controlled for season of when they were drawn (people tend to have the lowest vitamin D levels in the early spring, after a season of low sun exposure). However, the lowest octile of vitamin D levels measured was associated with a greatly increased risk of death by suicide. Levels above 20 were not associated with an increased risk of suicide.
Low vitamin D levels were common in active duty service members, and more than 30% had levels below 20. One might be be surprised by this finding… aren’t our military out in the sun all the time? However, a recent study of new recruits showed that vitamin D levels dropped over the summer (!) due to nighttime deployment and protective clothing. It is worthwhile to consider more aggressive supplementation.
Vitamin D is made in the skin. Thicker skin (for example, the torso) is more able to make it at the peak hours of 10-2pm. The face and hands deserve to be protected from the sun’s onslaught, and no one should get burned, but it might be reasonable to have some trunk time in the sun a few times a week for a few minutes in the late morning hours in the summertime. That might be a safer option than eschewing the sun altogether or using the chemicals in sunblock, which tend to do a great job of blocking the sunlight that creates vitamin D and allowing though the ultraviolet rays that can cause damage and cancer (which is more likely with low vitamin D levels…).
We evolved on a planet with a sun. Avoiding it altogether might have a cost we haven’t quite calculated yet.
Copyright Emily Deans MD