A healthy balance between vitamin D status and skin safety may be difficult to achieve in sunny climates. This is particularly important in young people who may suffer serious long term consequences from either vitamin D deficiency or excessive sun exposure. We recruited 262 healthy Australian women age 16 25 years (mean ± SD 22.3±1.2) via Facebook advertising and obtained extensive questionnaire data, UV exposure by calibrated dosimeter use, serum 25 hydroxyvitamin D (25 OHD) levels (Abbott Architect assay), Fitzpatrick skin type (higher score reflecting lesser sun sensitivity), skin melanin density (spectrophotometry of the inner upper arm) and actinic skin damage by silicone skin cast score (Beagley-Gibson grading). Mean serum 25 OHD was 60.7 nmol/L (range 20 201; 39% ≤ 50; n=186). Vitamin D status was inversely related to Fitzpatrick skin type (adjusted odds ratio [OR] 0.5, P=0.015), melanin density (adjusted OR 0.7, P=0.045), use of summer sun protective measures (adjusted OR 0.8, P=0.037), and positively associated with regular multivitamin use (adjusted OR 1.6, P=0.04). Of concern, median skin cast score was 3/6 (interquartile range [IQR] 2), and 4/6 (IQR 2) in 23-25 year-olds. Skin cast score was positively associated with recorded UV exposure after adjustment for Fitzpatrick skin type, age and daily smoking (p<0.01). These data indicate a high prevalence of moderate-to-severe actinic skin damage in young Australian women despite high prevalence vitamin D insufficiency. Moreover, several factors that reduce skin damage and skin cancer risk were shown to be associated with lower 25OHD levels. The findings raise concern whether it is feasible to maintain adequate vitamin D status while minimising skin ageing and skin cancer risk under climatic conditions of plentiful UV availability. Carefully-designed prospective studies and clinical trials are required to address this important problem.
Disclosure: The authors declared no competing interests. This work was supported by the Australian NHMRC, project grant number APP1049065.