Whether low levels of vitamin D cause depression, worsen it, or are a symptom of the underlying depression is not fully understood.
Dr Sonal Pathak said: “There is no solid proof that vitamin D deficiency causes depression. Large studies are clearly needed.”
Dr Pathak studied three women aged 42 to 66 who all suffered with depression.
All three were deficient in vitamin D, with levels that ranged from 8.9 to 14.5 nanograms per ng/mL.
The women received vitamin D therapy for eight to 12 weeks to replenish their blood levels.
After treatment, their levels increased to 32 to 38 ng/mL. The women also reported corresponding improvements in symptoms of depression following vitamin D therapy.