People who regularly take vitamin D supplements may have a lower likelihood of developing melanoma, according to study results published in Melanoma Research. The research was done in the North Savo region of Finland, which is near the Arctic Circle and gets little winter sunlight.

Vitamin D is an essential nutrient needed to maintain healthy bones. It also has anti-inflammatory and antioxidant properties, and it supports good immune function. Vitamin D is present in foods such as fortified milk and certain fish, and it can also be taken as a supplement. The body makes vitamin D when the skin is exposed to sunlight, but people with limited sun exposure may not make enough. This is a risk for people living at latitudes that get little sun for part of the year and those who spend most of their time indoors.

Ilkka Harvima, MD, PhD, of the University of Eastern Finland, and colleagues explored the potential link between vitamin D intake and the development of malignant skin conditions, including melanoma. Previous research on this has yielded conflicting results.

The study included 498 adults at risk for skin cancer who were recruited at the dermatology outpatient clinic of Kuopio University Hospital; 96 of them were immunocompromised. Based on their self-reported use of oral vitamin D supplements, they were split into three groups: nonuse, occasional use or regular use. After a skin examination, they were grouped according to their risk for skin cancer. The researchers measured blood levels of 25-hydroxyvitamin-D3 in 260 participants. Regular users of vitamin D supplements had the highest levels, while nonusers had the lowest levels.

Among participants who were not immunocompromised, vitamin D supplement use and serum vitamin D levels were not associated with facial or other photoaging (skin damage due to sun exposure), actinic keratosis (dry, scaly patches on the skin), the number of nevi (moles) or basal cell or squamous cell carcinoma, the most common types of skin cancer.

On the other hand, there was a clear association between vitamin D supplement use and melanoma. People who regularly took vitamin D supplements were about half as likely as nonusers to currently have melanoma or to have had it in the past (18% versus 32%). They were also less likely to have any type of skin cancer (62% versus 75%). What’s more, regular users had a lower skin cancer risk classification. Similar associations were seen for the 96 immunocompromised people.

In conclusion, “regular use of vitamin D associates with fewer melanoma cases when compared to nonuse, but the causality between them is obscure,” the study authors wrote.

“[T]he question about the optimal dose of oral vitamin D in order for it to have beneficial effects remains to be answered,” Harvima said in a press release. “Until we know more, national intake recommendations should be followed.”

Harvima noted that the melanoma mortality rate in the North Savo region of Finland is relatively high in relation to its incidence. “For this reason, too, it is worth paying attention to sufficient intake of vitamin D in the population in this region.”

Click here to read the study abstract in Melanoma Research.

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