In this review from 2018 of zinc and sperm fertilization ability, researchers found many links between zinc concentrations and healthy sperm counts and morphology (shape). An animal study found that zinc supplementation improved sexual dysfunction, potentially due to zinc’s ability to increase serum testosterone levels. In a human study, zinc supplementation was able to correct the negative effect on the thyroid and testosterone in males undergoing fatiguing exercise. Other animal studies have shown that zinc supplementation increased sperm counts and improved antioxidant activities.
Kerns K, Zigo M, Sutovsky P. Zinc: A Necessary Ion for Mammalian Sperm Fertilization Competency. Int J Mol Sci. 2018 Dec 18;19(12):4097. doi: 10.3390/ijms19124097. PMID: 30567310; PMCID: PMC6321397.