Plasma Zinc Concentration Responds Rapidly to the Initiation and Discontinuation of Short-Term Zinc Supplementation in Healthy Men

To assist with the evaluation of zinc (Zn) intervention programs information is needed on the magnitude and velocity of response of plasma Zn concentration following changes in Zn intake Our objective in this study was to measure plasma Zn concentration of healthy adult men before and after initiation and discontinuation of 1 of 2 dosages of Zn supplements or placebo We conducted a randomized double blind placebo-controlled trial in 58 apparently healthy males aged 19-54 y Participants received 1 of 3 liquid supplements daily for 21 d 10 or 20 mg Zn/d as Zn sulfate or placebo Fasting plasma Zn concentrations were measured on 14 occasions before during and after supplementation Data were analyzed using mixed-model ANCOVA The plasma Zn concentration was related to day of study (P < 0 0001) and study group (P < 0 0001) Controlling for baseline concentrations plasma Zn concentrations were consistently elevated above baseline by d 5 among individuals in both of the Zn-supplemented groups compared with those receiving placebo supplements regardless of their initial plasma Zn concentration There were no significant group-wise differences between those who received either 10 or 20 mg/d Zn Plasma Zn concentrations of supplemented individuals declined following withdrawal of supplementation and within 2 wk no longer differed from those of the placebo group Change in the plasma Zn concentration is a useful indicator to monitor compliance with and possibly effectiveness of Zn supplementation programs To ensure accurate interpretation of the results samples should be collected while the intervention is still in progress J Nutr 140 2128-2133 2010