Supplements for Mental Health, Part 2: Zinc

 Zinc is a metallic element, and an essential nutrient.  

It is toxic if ingested in excess, with various side effects such as nausea, headache, and diarrhea.  High-dose supplementation can cause copper deficiency, typically at doses greater than 100 mg/day.  The maximum recommended dose is 40 mg/day, with the standard daily requirement being around 10 mg/day.  

The prevalence of zinc deficiency in North America is about 7.5 %  In cases of deficiency, it is obviously beneficial to use supplements.  But what about supplementation above a baseline, normal dietary intake? 

There are some positive studies, including RCTs, typically using doses of about 25 mg per day.  But a few groups have shown negative results, including a major study of using several nutritional supplements, including zinc, all at once. (Sarris et al, 2019).  This group showed that placebo did considerably better than supplements, for treating depression.   

There is in particular no evidence of benefit from zinc supplementation in the treatment of COVID.  

Overall, the research is variable, often low-quality.  It is clear, once again, that zinc supplementation is very helpful in situations in which there could be nutritional deficiencies.  

But the risk of supplementing with zinc in a 25 mg per day range would be very low.  It could be on a list of things to try, as an adjunct for the treatment of depression or ADHD.  It would best be done on a randomized basis, for example to set up your own personal study to take either zinc or placebo for 6 weeks (with the truth of what you were actually taking unknown to you until the trial was over) then with repeated randomized 6-week trials several times, to assess any consistent change in symptoms between placebo and zinc trials.  

References

Lai, J., Moxey, A., Nowak, G., Vashum, K., Bailey, K., & McEvoy, M. (2012). The efficacy of zinc supplementation in depression: Systematic review of randomised controlled trials. Journal of Affective Disorders, 136(1), e31–e39. https://doi.org/10.1016/j.jad.2011.06.022

Duncan, A., Yacoubian, C., Watson, N., & Morrison, I. (2015). The risk of copper deficiency in patients prescribed zinc supplements. Journal of Clinical Pathology, 68(9), 723–725. https://doi.org/10.1136/jclinpath-2014-202837

Estimating the Global Prevalence of Zinc Deficiency: Results Based on Zinc Availability in National Food Supplies and the Prevalence of Stunting. (2012). PLOS ONE, 7(11), e50568. https://doi.org/10.1371/journal.pone.0050568

Yosaee, S., Clark, C. C. T., Keshtkaran, Z., Ashourpour, M., Keshani, P., & Soltani, S. (2022). Zinc in depression: From development to treatment: A comparative/ dose response meta-analysis of observational studies and randomized controlled trials. General Hospital Psychiatry, 74, 110–117. https://doi.org/10.1016/j.genhosppsych.2020.08.001

Sarris, J., Byrne, G. J., Stough, C., Bousman, C., Mischoulon, D., Murphy, J., Macdonald, P., Adams, L., Nazareth, S., Oliver, G., Cribb, L., Savage, K., Menon, R., Chamoli, S., Berk, M., & Ng, C. H. (2019). Nutraceuticals for major depressive disorder- more is not merrier: An 8-week double-blind, randomised, controlled trial. Journal of Affective Disorders, 245, 1007–1015. https://doi.org/10.1016/j.jad.2018.11.092

Thomas, S., Patel, D., Bittel, B., Wolski, K., Wang, Q., Kumar, A., Il’Giovine, Z. J., Mehra, R., McWilliams, C., Nissen, S. E., & Desai, M. Y. (2021). Effect of High-Dose Zinc and Ascorbic Acid Supplementation vs Usual Care on Symptom Length and Reduction Among Ambulatory Patients With SARS-CoV-2 Infection: The COVID A to Z Randomized Clinical Trial. JAMA Network Open, 4(2), e210369. https://doi.org/10.1001/jamanetworkopen.2021.036