The relationship between depression in adolescents and vitamin D was studied in a case-series that included effects of vitamin D supplementation.

Serum 25OH vitamin D (25OHD) levels in 54 Swedish depressed adolescents were investigated. Subjects with vitamin D deficiency were given vitamin D(3) over 3 months (n = 48). To evaluate well-being and symptoms related to depression and vitamin D status, the WHO-5 well-being scale, the Mood and Feelings Questionnaire (MFQ-S) and a vitamin D deficiency scale were used.

Mean serum 25OHD in the depressed adolescents was 41 at baseline and 91 nmol/L (p < 0.001) after supplementation. Basal 25OHD levels correlated positively with well-being (p < 0.05). After vitamin D supplementation, well-being increased (p < 0.001) and there was a significant improvement in eight of the nine items in the vitamin D deficiency scale: depressed feeling (p < 0.001), irritability (p < 0.05), tiredness (p < 0.001), mood swings (p < 0.01), sleep difficulties (p < 0.01), weakness (p < 0.01), ability to concentrate (p < 0.05) and pain (p < 0.05). There was a significant amelioration of depression according to the MFQ-S (p < 0.05).

This study showed low levels of vitamin D in 54 depressed adolescents, positive correlation between vitamin D and well-being, and improved symptoms related to depression and vitamin D deficiency after vitamin D supplementation.