Serum testosterone and urinary excretion of steroid hormone metabolites after administration of a high-dose zinc supplement

Abstract

Objectives: To investigate whether the administration of the zinc-containing nutritional supplement ZMA causes an increase of serum testosterone levels, which is an often claimed effect in advertising for such products; to monitor the urinary excretion of testosterone and selected steroid hormone metabolites to detect potential changes in the excretion patterns of ZMA users. Subjects: Fourteen healthy, regularly exercising men aged 22-33 years with a baseline zinc intake between 11.9 and 23.2 mg day À1 prior to the study. Results: Supplementation of ZMA significantly increased serum zinc (P ¼ 0.031) and urinary zinc excretion (P ¼ 0.035). Urinary pH (P ¼ 0.011) and urine flow (P ¼ 0.045) were also elevated in the subjects using ZMA. No significant changes in serum total and serum free testosterone were observed in response to ZMA use. Also, the urinary excretion pattern of testosterone metabolites was not significantly altered in ZMA users. Conclusions: The present data suggest that the use of ZMA has no significant effects regarding serum testosterone levels and the metabolism of testosterone in subjects who consume a zinc-sufficient diet.

Effect of Zinc and Selenium Supplementation on Serum Testosterone and Plasma Lactate in Cyclist After an Exhaustive Exercise Bout

“…Kilic concluded that "administration of a physiologic dose of zinc can be beneficial to performance." Contradictory, Koehler et al [40] noted that zinc supplementation may reverse lowered testosterone levels and restore disturbed testosterone metabolism in cases of mild or severe zinc deficiency; it is not capable of further increasing serum testosterone when sufficient zinc is provided by the regular diet. The disparity in results in the aforementioned studies with our findings might be due to variations in the consumed dose of zinc supplement, status of zinc in subjects, amount of zinc intake on diet, as well as the improper time duration for the effect of supplementation does in our study.…”

Analysis of the relationship between the blood concentration of several metals, macro- and micronutrients and endocrine disorders associated with male aging

“…Zn deficiency enhances apoptotic processes in the testis and negatively affects semen quality by reducing the number and motility of sperm (Kumari et al 2011). Research conducted by Koehler et al (2009) does not show a statistically significant increase in the concentration of TT and FT in young men supplemented with Zn (Koehler et al 2009). Jalali et al (2010) demonstrate that Zn supplementation of male hemodialysis patients results in increased concentrations of luteinizing hormone and testosterone.…”

A–Z of nutritional supplements: dietary supplements, sports nutrition foods and ergogenic aids for health and performance: Part 46

“…Wilborn et al 23 showed that 8 weeks of ZMA supplementation, combined with resistance training, resulted in no significant differences in the plasma concentrations of Zn or magnesium in anabolic (T, IGF-1 and GH) or catabolic hormones (cortisol), gains in muscle mass and strength or cycling anaerobic capacity when compared to placebo. Koehler et al 24 also reported, in a well-controlled study, that 56 days of ZMA supplementation in physically active males did not alter plasma total T, free T or urinary excretion of T metabolites.…”