Clinical Question

In patients with low vitamin D levels, does vitamin D supplementation improve symptoms of depression?

Bottom Line

Taken in aggregate, symptoms of depression do not improve in patients with low vitamin D levels when given vitamin D supplementation any more than when given placebo. There may be a benefit in patients with low vitamin D levels and mild to moderate depression. (Level of Evidence = 1b–)

Synopsis

This study was conducted in Norway, where researchers started by identifying patients with depressive symptoms and low vitamin D levels (< 22 ng per mL [< 55 nmol per L]). The authors excluded patients with severe depression (who were sent for treatment). The remaining 243 patients had a range of depression scores, although the percentage with mild to moderate depression was not reported. These patients were randomized, using concealed allocation, to receive oral placebo or cholecalciferol at a dosage of 40,000 IU weekly. After six months, vitamin D levels increased to normal in 97.5% of treated patients but in only 1.6% of the placebo group. However, there were significant improvements in depression scores in both groups, including an increase in global seasonality score, a measure of seasonal affective disorder. Patients with higher depression scores (who met the definition of depressive disorder) at the start of the study may have had a greater improvement in depression scores with treatment than patients receiving placebo, although this result needs to be confirmed by other studies.

Study design: Randomized controlled trial (double-blinded)

Funding source: Government

Allocation: Concealed

Setting: Outpatient (primary care)

Reference: KjærgaardMWaterlooKWangCEet alEffect of vitamin D supplement on depression scores in people with low levels of serum 25-hydroxyvitamin D: nested case-control study and randomised clinical trial. Br J Psychiatry.2012; 201( 5): 360– 368.