One of the most common questions I hear from my Miami dermatology patients is, “If I wear sunscreen every day will I become vitamin D deficient?”
My answer to this is always “no,” but let’s explore the practicalities of my answer.
Vitamin D is one of the only vitamins that we as humans can produce ourselves. It has been nicknamed “the sunshine vitamin” because the sun (UV light) stimulates its production. Vitamin D has been linked to the prevention of cancer, heart attacks, osteoporosis, immune system dysfunction, high blood pressure, and even falls in the elderly. But many of these claims may be overstated, according to a recently published article in The Lancet.
Although it is true that vitamin D plays an important role in prevention of some of these conditions in those with low levels of vitamin D, there is still debate on whether supplementation in healthy individuals yields the same results.
It is true that our bodies produce vitamin D in response to UV exposure, but the amount needed for this production is only about 5 to 10 minutes of midday Miami sun. Too much UV exposure can actually destroy the vitamin. In addition, many cases have shown that, despite UV exposure, people can still be vitamin D deficient. The elderly have a decreased ability to produce vitamin D and may require supplementation even if they are sun worshipers. Darker-skinned individuals may also need supplementation, especially if living in northern climates.
Deficiency is not related to sun exposure or lack thereof. The Institute of Medicine of the National Academies’ Recommended Dietary Allowance (RDA) for vitamin D is 600 IU (International Units) a day for people between the ages of 1 and 70, and 800 IU a day for people ages 70 and older. If you are deficient, then you will likely need doses much higher than this. Dietary sources include oily fish, milk, and vitamin D-fortified foods such as cereal and orange juice.
If you are concerned about vitamin D deficiency, then have your primary care physician draw your vitamin D levels. Overexposure to UV will only result in skin cancer and is not a cure for vitamin D deficiency.