Made in the skin through UVB exposure, the sunshine vitamin is a mainstay among dermatologists. They first recognized its ability to regulate skin cells while treating patients with psoriasis, a disease marked by warp-speed cell growth. More recently, “studies have shown that D3 can help activate hair growth by similar means—boosting the metabolism of the follicles and encouraging those cells to turn over in a more normal way,” says Michelle Henry, MD, a dermatologist in New York City. Dermatologists are also using D3 to treat acne, as it “strengthens the moisture barrier, preventing skin from drying out and then paradoxically unleashing more oil to protect itself from dehydration,” explains New York City dermatologist Whitney Bowe, MD.
The vitamin also regulates the skin’s antimicrobial system, turning on the production of antibacterial peptides called cathelicidins, which is why “without sufficient vitamin D3, we are more prone to developing infections and inflammatory conditions,” says Jeannette Graf, MD, a dermatologist in New York City. Bottom line: Since we create less D3 as we get older, and few foods are naturally rich sources, supplements are still essential. Dr. Graf encourages adult-acne patients to take 5,000 IUs a day. (Talk to your doctor before trying any new drug.)