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Very few studies have investigated the determinants of serum vitamin D levels using a set of variables that include simultaneously sun exposure, phototype, dietary intake, sociodemographics, anthropometric, lifestyle data, and genetic polymorphisms. Our objective was to investigate the associations between all these parameters and vitamin D status in a large sample of French adults. This cross-sectional survey was based on 1,828 middle-aged Caucasian adults from the SU.VI.MAX (SUpplémentation en VItamines et Minéraux AntioXydants) study. Plasma 25-hydroxyvitamin D (25OHD) concentration was lower among women (P<0.0001), older subjects (P=0.04), obese/underweight (P<0.0001), those living at higher latitudes (P<0.0001), those whose blood draw occurred in early spring (P<0.0001), less physically active (P<0.0001), with low sun exposure (P<0.0001), and with no-to-low alcohol intake (P=0.0001). Mutant GC rs4588 and rs7041 single nucleotide polymorphisms were associated with lower and higher 25OHD concentrations, respectively (P<0.0001). Dietary intake was not a major determinant of vitamin D status (P=0.7). This study provides an overall picture of determinants of vitamin D status. Several modifiable factors were identified, such as daily-life moderate sun exposure, physical activity, and normal-weight maintenance, which should be targeted by public health policies in order to improve vitamin D status in the general population, while avoiding active/intensive sun exposure, in line with recommendations for skin cancer prevention.

This study identifies a number of factors associated with the severity of melasma. Further epidemiological studies in this type of population, in particular, to investigate triggering factors, are justified by the aesthetic damage caused by melasma in dark-skinned patients, lack of efficacy of existing treatments, non-compliance with photoprotection recommendations and the challenge of treatment.

Whereas indoor tanning should be discouraged, it seems that indoor tanners are also regular sunbathers unconcerned about the risk of photoageing and skin cancer occurrence. Moreover, indoor tanners seem to have more behavioural risk factors for cancer, such as smoking.

This research aimed to test whether supplementation with a combination of antioxidant vitamins and minerals could reduce the risk of skin cancers (SC). It was performed within the framework of the Supplementation in Vitamins and Mineral Antioxidants study, a randomized, double-blinded, placebo-controlled, primary prevention trial testing the efficacy of nutritional doses of antioxidants in reducing incidence of cancer and ischemic heart disease in the general population. French adults (7876 women and 5141 men) were randomized to take an oral daily capsule of antioxidants (120 mg vitamin C, 30 mg vitamin E, 6 mg beta-carotene, 100 microg selenium, and 20 mg zinc) or a matching placebo. The median time of follow-up was 7.5 y. A total of 157 cases of all types of SC were reported, from which 25 were melanomas. Because the effect of antioxidants on SC incidence varied according to gender, men and women were analyzed separately. In women, the incidence of SC was higher in the antioxidant group [adjusted hazard ratio (adjusted HR) = 1.68; P = 0.03]. Conversely, in men, incidence did not differ between the 2 treatment groups (adjusted HR = 0.69; P = 0.11). Despite the small number of events, the incidence of melanoma was also higher in the antioxidant group for women (adjusted HR = 4.31; P = 0.02). The incidence of nonmelanoma SC did not differ between the antioxidant and placebo groups (adjusted HR = 1.37; P = 0.22 for women and adjusted HR = 0.72; P = 0.19 for men). Our findings suggest that antioxidant supplementation affects the incidence of SC differentially in men and women.

Skin sensitivity is a common concern that declines with age and is relevant for men as well as for women.

The objective of this study was to assess the association between melanocortin-1 receptor (MC1R) variants and the severity of facial skin photoaging. The study population comprised 530 middle-aged French women. A trained dermatologist graded the severity of facial skin photoaging from photographs using a global scale. Logistic regressions were performed to assess the influence of MC1R polymorphisms on severe photoaging with adjustment for possible confounders (demographic and phenotypic data and sun exposure intensity). Among the fifteen MC1R variants identified, the nine most common were V60L, V92M, R151C, R160W, R163Q, R142H, D294H, D84E, and I155T. One hundred and eighty-five individuals (35%) were WT homozygotes, 261 (49%) had one common variant, 78 (15%) had two common variants, and six (1%) had at least one rare variant. After adjustment for possible confounders, the presence of two common variants was already a risk factor for severe photoaging (AOR (95% confidence interval): 2.33 (1.17-4.63)). This risk reached 5.61 (1.43-21.96) when two major diminished-function variants were present. Surprisingly, the minor variant, V92M, was associated with increased risk of photoaging (2.57 (1.23-5.35)). Our results suggest that genetic variations of MC1R are important determinants for severe photoaging.