Vitamin D is unusual for a couple of reasons. First, it's really not a vitamin at all, it's a hormone. And second, it's obtained by exposure to sunlight, not through the foods we eat.
We are designed to get our vitamin D from sunshine; as our skin soaks up ultraviolet sunlight, it produces vitamin D with the help of the liver and kidneys. If you don't live in a sunny climate, your amazing body can store Vitamin D for use in the not-so-sunny months.
So go outside and get a few minutes of sun exposure every day possible - without the use of sunscreens. Sunscreens greatly reduce the ability of the skin to make Vitamin D (an SPF 8 product reduces it by 92.5%, while an SPF 15 sunscreen reduces it by 99%).
How much sun do you need? The Scientific Advisory Committee on Nutrition and the National Institutes of Health both recommend 200 International Units (IUs) of vitamin D per day. For Caucasians, exposing a large part of the skin to the summer sun for 20 – 30 minutes at one time provides about 10,000 IUs of vitamin D, which as you can see, is far more than enough. In spring, summer and fall, exposing the hands, face and arms to the noontime sun for only 5 minutes, 2 -3 times per week, is plenty for light-skinned people. People of Asian or Indian descent may require 3x as much sun under similar conditions, and those of African descent may need up to 10x in order to produce enough vitamin D.
That's not to say you should ever let yourself burn! If you expect to spend more time in the sun, start early in the season to build your tolerance for sun exposure, and cover up with loose clothing when necessary. Sunscreens contain dangerous chemicals that are carcinogenic and may, in fact, be partly responsible for the increase in skin cancer rates (read which sunscreens are the safest here).
There is a wide variety of Vitamin D supplements on the market, and certain foods such as dairy products are typically fortified with Vitamin D. The problem is that both of these practices are linked to many serious health concerns. Supplements are known to cause nutritional imbalances that can increase your bad cholesterol and contribute to kidney disease, immune system suppression, gastrointestinal issues, and even cancer.
For those who absolutely must take a supplement because limited movement prevents them from getting outdoors, the smallest supplement needed to meet the RDA requirement should be adequate. According to Dr. John McDougall, 200 IUs per day should be adequate (a far cry from the recommended levels of 2,000 – 4,000/day). He contends that “normal values” for vitamin D have become exaggerated, and that the current standards are too high; he lists plenty of recent scientific literature references which backs him up.
Fortunately, a 2010 report from the Institute of Medicine concluded that very few people are actually vitamin D deficient, and that there is no benefit to increasing blood plasma levels of vitamin D to over 20 ng/ml for healthy people.
Lastly, the best way to protect yourself against skin cancer is to consume the "Plan A" diet, which is low in fat and high in antioxidant-rich foods. There is strong evidence that diet has a profound effect on the development or prevention of skin cancer, which is not surprising since we know diet has an effect on all types of cancer. If you would like the references or more information on this topic, please contact [email protected].
The Lord provides sun for light by day, the moon and the stars to shine at night. He stirs up the sea and makes it roar; his name is the Lord Almighty. (Jeremiah 31:35, GNT)