The Social Sunshine of the Arctic Youth: Exploring friendship’s influence on Vitamin D levels

Background Vitamin D status correlates with 25OHD levels which depends on nutritional intake and UVB exposure. These two factors are influenced by friends, as people tend to participate in the same activities or eat a similar diet to their peers. Objectives Investigate how social interactions in a general high school population above the Arctic Circle influence 25OHD levels in the population. Methods The Fit Futures 1 study was performed over 8 months and interview data on social contact among 1038 first-level students in 8 high schools in Northern Norway were collected. Serum levels of 25OHD were measured (n = 890). The participants filled in a questionnaire about nutritional consumption, solarium habits, ethnicity, and chronic diseases. The participant’s BMI was also measured. Results Once high schools’ social biases were accounted for, only UVB radiation levels explained the differences in 25OHD levels. For non-solarium users, logistic regression analysis showed a positive correlation between a person’s 25OHD levels and the 25OHD level of friends in the general population and within the same high school for most of the schools. We saw that women can influence other women into going to the solarium, while this influence was not present for men. Conclusions 25OHD levels can be influenced by social networks. This study can help to add weight to current public health recommendations due to the positive spillover effect in the network.