Main Points
Zinc provides a wide variety of general health benefits and it may positively influence cognition, mood, and well-being. Interestingly, both a deficiency and a surplus of zinc in the brain have been correlated with memory impairment [1, 2].
Zinc supplementation has been shown to improve cognitive performance and taste acuity in a study of adolescent girls [3].
Additionally, correcting for zinc deficiencies has been shown to restore memory and cognition in stroke patients [4].
Zinc is highly concentrated in the hippocampus region of the brain, and deficiency of this mineral is associated with both mood disorders and impaired memory formation [5, 6, 7]. Specifically, zinc deficiency is highly correlated with decrements in spatial memory, thought to result from impaired BDNF signaling (a pathway associated with neuronal growth and plasticity) [8, 9, 10].
In a mouse model, zinc-fortified water given throughout the lifespan had neuroprotective effects compared to control, indicating that zinc may aid in preventing decline in memory over time [11].
It is theorized that zinc may reduce the accumulation of the protein beta-amyloid (which is linked to the onset of neurodegenerative diseases) in the brain as well as improve mitochondrial function and BDNF levels [12].
Depressed patients appear to have reduced levels of serum zinc, and the magnitude of the deficiency is related to the severity of the depression [13, 14, 15].
Zinc supplementation is effective as an adjunct therapy alongside traditional antidepressants, but it may also reduce depressive symptoms in otherwise healthy individuals via increased BDNF [16].
The results of a 6-month trial showed improvements in mood in a population of young, healthy women after supplementing with 7 mg elemental zinc [17]. Another study showed that 30 mg elemental zinc taken daily for 12 weeks was associated with improvements in depressive symptoms compared to placebo [18].
Studies involving rats have shown that depressive and behavioral symptoms were improved upon normalizing zinc levels after a period of two weeks of zinc deprivation [19, 20].
Zinc is thought to inhibit the enzyme glycogen synthase kinase-3B (BSK3B) which is a molecular target for mood disorders [21, 22, 23].
Cases of nausea have been reported when zinc is taken on an empty stomach and at high doses.