Researchers have found that high doses of vitamin D could help to treat sunburn.

Redness, blistering, and soreness are just three of the dreaded symptoms of sunburn. But according to new research, these symptoms could be reduced with a vitamin resulting from sun exposure: vitamin D.

In a pilot study, researchers found that participants who took high doses of vitamin D within an hour of sunburn experienced a reduction in swelling and inflammation.

Senior study author Dr. Kurt Lu, an assistant professor of dermatology at Case Western Reserve University in Cleveland, OH, and colleagues recently reported their findings in the Journal of Investigative Dermatology.

While many of us welcome a hot, sunny day with open arms, we need to make sure those arms are well protected.

According to the Centers for Disease Control and Prevention (CDC), just 15 minutes of ultraviolet (UV) radiation from the sun is enough to cause skin damage.

As such, the CDC recommend wearing broad-spectrum sunscreen (SPF15 or higher), a wide-brimmed sun hat, sunglasses, and other protective clothing - such as a long-sleeved shirt - to help prevent UV-related skin damage.

Many of us are well aware of these recommendations, but more than a third of us still get sunburnt, which can result in red, sore, blistering skin. The new study from Dr. Lu and team, however, suggests that vitamin D supplementation might help to ease the symptoms of sunburn.

Vitamin D and sunlight

Vitamin D is considered an essential nutrient. It not only aids bone health by promoting calcium absorption, but it also plays a role in nerve signaling and immune system functioning.

The National Institutes of Health (NIH) recommend that individuals aged 14 to 70 years get an average of 600 international units of vitamin D every day.

Vitamin D is naturally present in small amounts in some foods, including fatty fish, cheese, and eggs. However, the body's main source of vitamin D is the sun.

Our skin contains a chemical compound called 7-Dehydrocholesterol. When exposed to sunlight, this compound produces vitamin D-3. However, due to the risks of excess UV exposure, getting all the vitamin D we need from sunlight is not always feasible.

For people who are unable to achieve vitamin D recommendations through diet and sunlight exposure, vitamin D supplements are an alternative.

But the new research suggests that, in high doses, vitamin D supplements may do more than just boost vitamin D levels.

Vitamin D activates skin repair genes

Previous research has suggested that vitamin D can help to reduce inflammation of the skin. For the new study, Dr. Lu and colleagues set out to determine whether the vitamin could reduce skin inflammation caused by sunburn.

To reach their findings, the team enrolled 20 participants, all of whom were given a small "sunburn" on their inner arm, induced by exposure to a UV lamp.

Next, the participants were randomly assigned to one of four groups. One group received a placebo pill, while each of the other groups received vitamin D in a single dose of either 50,000, 100,000, or 200,000 international units.

The team collected skin biopsies from each subject at four time points after they became sunburnt: 24 hours, 48 hours, 72 hours, and 1 week.

Compared with participants who took the placebo, subjects who received vitamin D experienced a reduction in skin inflammation.

What is more, the team found that the highest doses of vitamin D not only led to a reduction in skin redness, but they also activated skin repair genes, including an anti-inflammatory enzyme called arginase-1.

"We hypothesize that vitamin D helps promote protective barriers in the skin by rapidly reducing inflammation," says Dr. Lu. "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."

While the results suggest that vitamin D supplementation may be an effective treatment for sunburn, Dr. Lu and team caution that the doses used in their study are much higher than the current daily recommendations.

    "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."

    Dr. Kurt Lu

The researchers now plan to investigate whether vitamin D could aid the treatment of burn patients.