We are one of the few animals on earth without feathers, scales or fur. It turns out to be a bit risky not to have a covering on the skin, but there may be some advantages to being hairless. Though we don’t have fur to block the sun we are able to make a portable, temporary sunscreen that allows us to protect our skin from the sun when we need to. All animals on the planet, as far back as insects, fish and reptiles use their skin to make vitamin D, and so do we. We make vitamin D from the UVB rays of the sun as they hit our skin, but only outside and with direct sun exposure. UVB is the only wavelength of light that changes 25 dehydroxycholesterol in our skin to a “pre” vitamin D, the chemical that then becomes vitamin D25 OH. The clothing that we wear and the sunscreen that we put on both block the UVB rays. They also block the production of vitamin D on the skin! Because the D in most food supplements is vitamin D2, (D2 is what rats, nocturnal animals, use), the food supplementation that the US government has provided in milk does not replace the vitamin D3 made on the skin. (Most doctors do not know the difference, and the current Family Practice recommendations are still vitamin D2 50,000 IU once a week.)
How to use the melanin in your skin to your and your child’s advantage:
Human skin coloring is based on a chemical called melanin. Melanin is a chemical that is designed to absorb energy. In the skin it is used to absorb potentially damaging UVB light. High energy light rays of UVA and UVB frequency from the sun or from a tanning bed can damage the DNA in our skin cells. That damage, if not repaired, can lead to skin cancer. We hairless beings incorporated a wonderful, home-made sunscreen into the surface of our skin. We can make it on demand and adjust it in relation to our sun exposure. We also use the vitamin D on our skin to repair that same DNA damage. So… way, way before doctors or sunscreen ever existed, our bodies had this all worked out!
In summary: be smart, be careful, listen to your body. If you can make enough vitamin D in the summer to make you sleep all the way through the winter then you don’t need to supplement. The bad effects of vitamin D deficiency don’t happen in one season, they accumulate over years of sleeping badly and not repairing our body for years on end. In normal populations that lived away from the equator there was a normal yearly change in the vitamin D blood level. It went up in the Fall and down again in the Spring. Probably, if the lowest Winter D level was 40 ng/ml the intestinal bacteria changed enough for us to gain a little weight, then when the D went up again in summer the normal bacteria grew back and we would lose the extra pounds.
2 thoughts on “Sun Exposure is the Natural Way to Make Vitamin D”
What about those 10,000 Lux bright light therapy lights? Are they a beneficial for insomniacs? If so, how would you suggest they be used and at what time of day for a person like myself who doesn’t see the sun all winter and works indoors with no windows all year?
I fit the mold you describe…I wake up after 3.5-4 hours every night and can’t fall back asleep. I’m tired generally all day and then alert at night. I have GAD, IBS, GERD, and a hiatal hernia. My D level ranges from 26-32 depending on the time of year. My PCP always told me that was ‘just a little below normal,’ and it was fine and typical for people in my area. Funny, even before I heard of you, Dr. Gominak, I felt there had to be a connection between my D levels and insomnia!
Thank you for sharing your research publicly! I’m excited and hopeful about following your protocol.
Dear Sarah: in response to your question about the lights they do affect the 24 hour circadian cycle, BUT it turns out we have two cycles, one that is attached to vitamin A , retinoids, or retina which senses light, and vitamin D which attaches us to the annual cycle. Because there’s such a big survival advantage to sleeping longer in the winter vitamin D also affects sleep and it is my belief based on my patients and their vitamin D levels that it is the major cause of the epidemic of sleep disorders that has occurred in the last 40 years. The only lights that make D on your skin are UVB lights and they cause sunburn or suntan at the same time so the wavelength of light being emitted by the bulb determines its effect. Because of the widespread use of sunscreen and our inside work most people find it easier to use oral vitamin D.