A study conducted by the University of Eastern Finland and Kuopio University Hospital found that fewer cases of melanoma were observed among regular users of vitamin D supplements. Experienced dermatologists also estimated that those taking vitamin D supplements regularly had a significantly lower skin cancer risk. The study, published in Melanoma Research, involved nearly 500 individuals at elevated risk for skin cancer and showed that those who took vitamin D supplements regularly had a reduced incidence of melanoma compared to non-users.
Vitamin D is vital for the proper functioning of the human body and may be implicated in various diseases. There has been extensive research on the relationship between vitamin D and skin cancers, with a focus on calcidiol, a metabolite of vitamin D, and its correlation with skin cancers. Previous studies have centered around examining serum levels of calcidiol and its link to skin cancers.
Findings from these studies have been inconclusive and even contradictory at times, as serum calcidiol levels have been associated with both a slightly higher and a slightly lower risk of different skin cancers. This may, in part, be explained by the fact that serum calcidiol analyses do not provide information on the metabolism of vitamin D in the human skin, which can express enzymes that generate biologically active vitamin D metabolites or inactivate them.
The new study, conducted under the North Savo Skin Cancer Programme, took a different approach: 498 adult patients estimated to have an increased risk of a skin cancer, such as basal cell carcinoma, squamous cell carcinoma, or melanoma, were recruited at the dermatological outpatient clinic of Kuopio University Hospital. Experienced dermatologists at the University of Eastern Finland carefully analyzed the patients’ background information and medical history and examined their skin.
The dermatologists also classified the patients into different skin cancer risk classes, namely low risk, moderate risk, and high risk. Based on their use of oral vitamin D supplements, the patients were divided into three groups: non-users, occasional users, and regular users. Serum calcidiol levels were analyzed in half of the patients and found to correspond to their self-reported use of vitamin D.
A key finding of the study is that there were considerably fewer cases of melanoma among regular users of vitamin D than among non-users and that the skin cancer risk classification of regular users was considerably better than non-users. Logistic regression analysis showed that the risk for melanoma among regular users was considerably reduced, more than halved, compared to non-users.
The findings suggest that even occasional users of vitamin D may have a lower risk for melanoma than non-users. However, there was no statistically significant association between the use of vitamin D and the severity of photoaging, facial photoaging, actinic keratoses, nevus count, basal cell carcinoma, and squamous cell carcinoma. Serum calcidiol levels were not significantly associated with these skin changes, either. Since the research design was cross-sectional, the researchers were unable to demonstrate a causal relationship.
Other relatively recent studies, too, have provided evidence of the benefits of vitamin D in melanoma, such as the association of vitamin D with less aggressive melanoma.
“These earlier studies back our new findings from the North Savo region here in Finland. However, the question about the optimal dose of oral vitamin D in order to for it to have beneficial effects remains to be answered. Until we know more, national intake recommendations should be followed,” Professor of Dermatology and Allergology Ilkka Harvima of the University of Eastern Finland notes.
Researchers at the University of Eastern Finland and Kuopio University Hospital have previously reported (BMC Cancer 2021) that the melanoma mortality rate in North Savo is relatively high in relation to its incidence.
“For this reason, too, it is worth paying attention to the sufficient intake of vitamin D in the population in this region,” Harvima concludes.
Reference: “Regular use of vitamin D supplement is associated with fewer melanoma cases compared to non-use: a cross-sectional study in 498 adult subjects at risk of skin cancers” by Emilia Kanasuo, Hanna Siiskonen, Salla Haimakainen, Jenni Komulainen and Ilkka T. Harvima, 14 November 2022, Melanoma Research.