High doses of vitamin D taken one hour after sunburn may significantly reduce skin redness, swelling, and inflammation, a study claims. Researchers conducted a clinical trial in which 20 participants received a placebo pill or 50,000, 100,000, or 200,000 international unit of vitamin D one hour after a small ultraviolet lamp 'sunburn' on their inner arm. They followed up with the participants 24, 48, 72 hours and one week after the experiment and collected skin biopsies for further testing. The researchers from Case Western Reserve University in the US found that 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, researchers said. "We found benefits from vitamin D were dose-dependent," said Kurt Lu, assistant professor at Case Western Reserve University. Researchers hypothesized 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," Lu said. Also Watch: 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. "I would not recommend at this moment that people start taking vitamin D after sunburn based on this study alone. But, the results are promising and worthy of further study," Lu said. The study was published in the Journal of Investigative Dermatology.