Could sunscreen affect vitamin D deficiency? Yes!
According to Dr. Henry W. Lim, chair emeritus of the department of dermatology at the Henry Ford Health System and former president of the American Academy of Dermatology, if sunscreen is applied in a thick layer, it can effectively block sunlight and cause a lack of synthesis of vitamin D.
According to him, a thick layer approximately equal to 1 ounce, or the size of one golf ball, for the whole body, CNN reported.
"However, in the real world ... most people apply less than this amount," Lim added. In other words, "the 'in use' SPF is actually lower than the labeled SPF.”
Thus, you may not have to worry about vitamin D deficiency unless you use enough sunscreen. Those who generously use sunscreen and scrupulously wear hats and clothing with SPF protection will have a higher chance of vitamin D deficiency.
Vitamin D is synthesized in the skin when it is exposed to ultraviolet rays from the sun. Thus, if from 15% to 20% of the body surface is exposed to sunlight without protection for 15-20 minutes, two to three times a week, an adequate level of vitamin D can be achieved. But even with a low level of sunlight, the cumulative damage from the sun can happen for a long time, Lim explained.
"When the skin tans, there is DNA damage, and so with repeated low-dose exposure, the DNA damage could accumulate and potentially increase the risk of skin cancer and photoaging," Lim said. Squamous cell and basal cell carcinoma are the most common skin cancers in humans, and are correlated with the degree of one's sun exposure, while melanoma, the deadliest form of skin cancer is often the result of more intermittent, intense sun exposure, Lim explained.
"Patients need to use sun protection to minimize their risk for skin cancer, and yes it does impede the body's ability to make vitamin D. I tell patients if we found out cigarette smoking increased vitamin D levels, we wouldn't tell patients to smoke," said Dr. Patricia Farris, a dermatologist and fellow of the American Academy of Dermatology. "In other words, you can't recommend exposing patients to a known carcinogen (UV light) just to raise their vitamin D levels."
To reduce the risk of skin cancer and skin aging, dermatologists recommend practicing reasonable photo protection. This means wearing wide-brimmed hats, sunglasses and sunglasses.
A broad-spectrum sunscreen with an SPF of 30 or higher, which protects against harmful UVA and UVB rays, should be generously applied to all exposed areas of the body when you are outdoors for an extended period of time to minimize risk.
As for getting enough vitamin D, Lim recommends taking a multivitamin daily, which usually contains that amount of vitamin D that would provide enough vitamin A in the blood. Optimizing vitamin D levels is important for bone health and can help minimize bone thinning and the risk of fractures.