Anyone who has ever had bad sunburn understands the agonizing discomfort associated with too much sun exposure and would probably try just about any tactic to relieve their pain. Now, researchers at Case Western Reserve University (CWRU) School of Medicine and University Hospitals Cleveland Medical Center have recently released results from a small double-blinded, placebo-controlled clinical study where participants were given high doses of oral vitamin D one hour after sunburn, which was shown to reduce skin redness, swelling, and inflammation significantly. Findings from the new study were published in the Journal of Investigative Dermatology, in an article entitled “Oral Vtamin D Rapidly Attenuates Inflammation from Sunburn: An Interventional Study.”
The researchers designed the study so that 20 participants were randomized to receive a placebo pill or 50,000, 100,000, or 200,000 IU of vitamin D one hour after a small UV lamp “sunburn” on their inner arm. Investigators subsequently followed up with the participants 24, 48, and 72 hours and one week after the experiment and collected skin biopsies for further testing.
“We designed an interventional study to test the hypothesis that oral vitamin D would be capable of rapidly attenuating experimental sunburn,” the authors wrote. “Twenty healthy adults were randomized, in a double-blinded fashion, to receive either placebo or a high dose of vitamin D3 (cholecalciferol) one hour after experimental sunburn-induced by an erythemogenic dose of simulated solar radiation. As compared to placebo, participants receiving vitamin D3 (200,000 IU) demonstrated reduced expression of the pro-inflammatory mediators TNF-α [tumor necrosis factor-α] (p=0.04) and iNOS [inducible nitric oxide synthase] (p=0.02) in skin biopsy specimens 48 hours after an experimental sunburn.”
Participants who consumed the highest doses of vitamin D had long-lasting benefits—including less skin inflammation 48 hours after the burn. Participants with the highest blood levels of vitamin D also had less skin redness and a jump in gene activity related to skin barrier repair.
“We found benefits from vitamin D were dose-dependent,” explained lead study investigator Kurt Lu, M.D., assistant professor of dermatology at CWRU School of Medicine and University Hospitals Cleveland Medical Center. “We hypothesize that vitamin D helps promote protective barriers in the skin by rapidly reducing inflammation. What we did not expect was that at a certain dose, vitamin D not only was capable of suppressing inflammation, it was also activating skin repair genes.”
Interestingly, by measuring gene activity in the biopsies, the researchers also uncovered a potential mechanism underlying vitamin D skin repair activity. The results suggest vitamin D increases skin levels of an anti-inflammatory enzyme, arginase-1. The enzyme enhances tissue repair after damage and helps activate other anti-inflammatory proteins.
The authors noted that the findings in the new study “demonstrate that oral vitamin D is capable of rapidly attenuating experimental sunburn, and implicate arginase-1 up-regulation as a novel mechanism by which vitamin D exerts anti-inflammatory effects in humans. These results have broad implications for the role of vitamin D in skin homeostasis, and suggest that oral vitamin D may be clinically therapeutic for its immunomodulatory properties.”
While the investigators were excited by their discoveries, they cautioned that the trial tested very high doses of vitamin D that far exceed daily allowances. The FDA's recommended adult daily allowance for vitamin D is only 400 IU. The research team is planning additional studies that could inform treatment plans for burn patients.
“I would not recommend at this moment that people start taking vitamin D after sunburn based on this study alone,” Dr. Lu stressed. “But, the results are promising and worthy of further study.”