Hi everybody! I had a request to talk about vitamin D this week. Seems I’m not the only one feeling sun-starved this time of year! This is an awesome topic. Thanks Michelle!
So what’s vitamin D? Vitamin D is not actually a vitamin but a prohormone that is produced in the skin in response to sun exposure, actually UVB exposure. The farther away from the equator one is, the greater the angle the sun’s rays from straight-up-and-down and the less intense the UVB exposure. In Cleveland we are at 41 degrees north latitude and we have a “vitamin D winter” from November to March or so. This means that if you were lying naked in the sun in February (NOT RECOMMENDED!!) you could not make vitamin D at all. In Cleveland we need to supplement vitamin D in the winter.
What does vitamin D do? There are receptors for vitamin D in every cell in your body. Vitamin D is a powerful hormone that regulates expression of genes, turning some on and others off. Its most well-known action is regulating calcium metabolism and bone health. Vitamin D deficiency contributes strongly to osteopenia and osteoporosis. Scientists are furiously researching the many roles of vitamin D and more studies are published every day.
How do you get vitamin D? Today, February 23rd, in Cleveland, there’s only one way to get vitamin D and that’s to eat it. It is available in dairy milk and other foods that are fortified with vitamin D, and as supplements. What kind should you take? Vitamin D3, or cholecalciferol, is the best form to choose. D2, or ergocalciferol, requires some metabolism by the body before it’s active.
How do you get vitamin D from the sun? Well first of all you need to be outside with exposed skin on a sunny day! The best time of day to get your vitamin D is between 10 and 2, or anytime your shadow is shorter than you are. The skin must be exposed, and you must be outside – UVB doesn’t penetrate clothing or window glass. How much time is required? According to the Vitamin D council, “… one will have made all the vitamin D they are going to make for the day in about one-half the time it takes for their skin to turn pink.” So extended exposure and risking sunburn is not necessary. The torso makes the most vitamin D, the arms and legs less, and the face and hands next to none.
What about sunscreen? If you wear sunscreen you don’t make vitamin D. Period. SPF 8 blocks 95% of vitamin D production, and SPF 30 blocks it all.
What about tanning beds? There have been studies showing higher blood levels of vitamin D in those who use tanning beds. Maximal vitamin D production requires only a few minutes of exposure to the high-intensity UVB rays of a typical tanning bed, much less than is required to actually stimulate melanin production (i.e. tanning).
So how do we get enough vitamin D without risking sunburn and skin cancer? That’s a tough one and there is no consensus at this point. Some doctors are suggesting 10-15 minutes of bright-sun exposure BEFORE applying sunscreen. Other suggestions involve supplementing (2000-5000 units daily) and using sunscreen anyway.
It is interesting to note that vitamin D deficiency increases the risk of sunburn. There is evidence that the heat (i.e. dilation of blood vessels and increased blood flow) from sunburn increases vitamin D production in the skin. So sunburn (more likely with vitamin D deficiency) helps to correct the deficiency! Science is so cool 🙂 There are tanning salons that sell 10,000 IU vitamin D tablets to be taken for a month prior to starting tanning. This decreases the risk of burning, increases the amount of time you can tolerate in the bed, and makes you tan faster. If you’re going south for Spring Break and want to reduce your sunburn risk, start now with the vitamin D supplements!
I’m very excited that spring is coming. Can’t wait for the opportunity to let my skin make some vitamin D again! And yes, I take my vitamin D, I don’t want to burn 🙂