Friday, October 29, 2010

Zinc Supplementation Works Within Days

Zinc is probably among the most popular bodybuilding and fitness supplements on the market. Thus, it may interest you that a recent study by Wessels et al. (Wessels. 2010) found that taking supplemental zinc will increase serum zinc levels within 5 days:
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. [...] 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.
What is particular interesting is that there was no difference in zinc levels regardless of the amount of zinc the subjects received. Here, we obviously have another instance of "more ain't more" and "more certainly ain't better" - the latter goes hand in hand with information on the interference of zinc supplementation with copper and iron metabolism which previously reported on the SuppVersity.