Vitamin D helps to maintain normal levels of calcium and phosphorus in the blood. It helps the body absorb calcium, which is important for bone strength. Studies show that vitamin D boosts immunity, lowers the risk of cancer and helps stave off depression. A deficiency can contribute to weak bones and muscles, as well as pain. People at a higher risk of deficiency include the elderly, obese, or those with limited sun exposure.
We can get vitamin D in 3 ways: sun exposure, diet, and supplementation. According to the Institute of Medicine (IOM), most people get enough of the vitamin with diet and sun exposure. Foods that are high in vitamin D include fish, eggs, cod liver oil, and fortified milk and orange juice.
As mentioned, sunlight (outside, not through a window) is a great source of vitamin D, but comes along with a risk of skin cancer, discolorations, and wrinkles! 20-25 minutes of sun is all that we need, with the exception of elderly and darker-skinned people, for whom it may not be effective . Previous studies have stated that wearing sunscreen blocks the absorption of vitamin D; however, more recent studies have concluded otherwise. Antony Young, a professor of experimental protobiology, has determined that sunscreen won’t block off the sun you need for adequate vitamin D – and that wearing sunscreen is simply the smarter thing to do.
Unfortunately, for those of us who live significantly north of the equator, our sun exposure is very limited during the winter months. That’s when vitamin D supplementation might be a good idea. 4000 IU/day is typically an acceptable amount of vitamin D according to the IOM, but you must take into consideration all of your sources of vitamin D – diet, sun and supplementation.
Vitamin D can have side effects and cause adverse reactions in people with certain health conditions such as diabetes or blood pressure disorders. It can also interact with medications and supplements. It’s usually a good idea to check with your doctor before starting a new vitamin. Your doctor may inform you of potential drug interactions. He/she will likely do a blood draw to check your vitamin D level to see if you would benefit from increasing your intake.