Major depression: Getting a little help from zinc

In patients with major depressive disorder (MDD) being treated with antidepressants, zinc supplementation contributes to a substantial reduction in depressive symptoms, a study has found.

The researchers searched multiple online databases for trials that assessed whether zinc supplementation could prevent depression in healthy individuals or reduce depressive symptoms in those with MDD. The initial search yielded 12,322 articles. Six studies were included in the review, and five of these were pooled for the meta-analysis.

Two studies were conducted in Poland, one in Guatemala, one in Japan, and one in Iran. Only one study involved children. Duration of supplementation ranged from 10 to 12 weeks, with doses varying between 7 mg and 25 mg, administered daily or weekly.

Compared with placebo, zinc supplementation produced a significant reduction in the Beck Depression Inventory score (standardized mean difference [SMD], –0.36, 95 percent confidence interval [CI], –0.67 to –0.04).

Results were consistent in the subgroup of individuals aged ≥40 years (SMD, –0.61, 95 percent CI, –1.12 to –0.09).

One way that zinc may reduce depression symptoms is by inhibition of the ionotropic glutamate receptor N-methyl-D-aspartate (NMDA), the activation of which facilitates increased glutamatergic neurotransmission, which is in turn associated with depression and neurotoxicity, according to the researchers. [Pol J Pharmacol 2001;53:641-645; Prog Neuropsychopharmacol Biol Psychiatry 2011;35:693-701]

Zinc aids in the function of brain and neural structures by modulating synaptic transmission and acting as an endogenous neuromodulator of important receptors such as NMDA and a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic (AMPA), and c-aminobutyric acid (GABA), they added. [Brain Res Rev 2009;62:33-44]