Background: Seasonal Affective Disorder (SAD) is a sub-type of depression that only occurs during the winter months. A reduction in vitamin D may be linked to SAD. Since vitamin D deficiency has been reported to be common in older people, vitamin D supplementation may be expected to reduce seasonal mood disturbance in this group.
Objective: To assess the effect of vitamin D supplementation on the mental health of older women.
Setting: Primary care in three areas of the UK (Herts, Newcastle, York).
Subjects: Women aged 70 years or more recruited to the trial in the months May-October.
Intervention: Eligible women were randomised to receive calcium and vitamin D supplementation or no supplementation.
Outcome measure: At baseline and the six monthly assessment the mental component score (MCS), calculated from the SF-12 questionnaire was used to assess participants' subjective psychological well-being.
Results: A total of 2117 women recruited to the trial had their baseline measures taken between the months of May-October (1205 woman in the control group and 912 women in the intervention group). Of these women, 1621 had a MCS score at baseline and six months. Comparison of the six month mean MCS scores, adjusting for baseline MCS score and age, showed there was no significant difference between the two scores (p = 0.262).
Conclusions: Supplementing elderly women with 800 IU of vitamin D daily did not lead to an improvement in mental health scores.