Vitamin D is an important nutrient that helps regulate calcium and phosphorus levels, two minerals important for bone health. It’s even thought to play important roles in dementia, such as Alzheimer’s disease, and cold and flu. There’s no doubt that vitamin D is an important nutrient for overall well-being! You may know of vitamin D as the “sunshine vitamin”. Unlike other nutrients, our bodies are capable of producing vitamin D upon exposure to UV rays from the sun. While “soaking up the vitamin D” may sound simple, behind the scenes our bodies are working away at a complex process that turns sunlight into this crucial nutrient.
First, UVB rays from the sun convert 7-dehydrocholesterol (7-DHC), a substance present in our skin, into pre-vitamin D3. The success of this step depends on the amount of melanin present in our skin, and our exposure to UV rays from the sun. Melanin, which gives skin its colour, absorbs UV radiation. While this acts as natural sun protection, it prevents the UV rays from reaching the 7-DHC in our skin.¹ Skin colour influences skin type, and if you’ve read our previous post, you’ll know that during July in Boston, MA, someone with skin type I needs to spend 4 minutes under the sun at noon to get 1000 IU of vitamin D, while someone with skin type III needs to spend 7 minutes.²
After pre-vitamin D3 is produced, it is converted into vitamin D3. Then, some more steps occur in the liver and kidneys to convert vitamin D3 into the form used by our bodies: 1,25-dihydroxy vitamin D3.¹ This biologically active form is also known calcitriol.
The exact same UV rays that help our bodies produce vitamin D are the ones that cause sunburn. Sunburns are uncomfortable and can lead to skin cancer, but the sun is a valuable natural source of vitamin D. It’s important to achieve a healthy balance of sun safety and vitamin D production.