Zinc is an element that is found naturally in many foods. It is necessary to regulate our metabolism and maintain a strong immune system. Over the last 20 years, researchers have determined that it also plays a role in mental health.
Zinc is highly concentrated in the brain (second only to iron) and maintains the "blood brain barrier", or BBB. The BBB surrounds and protects the brain from many things. Studies show that a zinc deficiency in animals reduces the strength of the BBB, thus possibly increasing the risk for Alzheimer's and Parkinson's.
A recently published meta-analysis of 17 clinical studies concluded that the blood zinc concentration in depressed individuals is 1.85 umol/l lower (approximately 12.3 percent) than in a non-depressed control group. Additionally, there was evidence that incrementally lower zinc levels correlated positively with the severity of clinical depression.
Potential causes for zinc deficiency include alcohol abuse, diabetes, sickle cell disease, chronic infection, a vegetarian diet without supplements and anorexia. Those over 65 face the additional issue of poor zinc absorption and of course a poor diet, while not quantified, could logically be expected to contribute.
Many of the above medical problems are also seen in the depressed population, thus causality as always is the question. Nonetheless, this analysis certainly lends credence to a link between depression and low blood zinc levels.
The best news is summed up by researcher Walter Swardfager, Ph.D., “A growing body of evidence demonstrates that experimental zinc deficiency can induce depressive-like behavior in animals, which can be effectively reversed by zinc supplementation."
Though a blood test is optimal for determining your zinc level, two signs of deficiency include brittle hair that easily falls out and white bands on the fingernails.
Here’s more information on zinc and mental health.