Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 30, 2001
Publication Date: February 1, 2002
Citation: Lukaski, H.C. 2002. Adverse effects of dietary zinc restriction on cardiorespiratory function during exercise in men [abstract]. American Journal of Clinical Nutrition. 75:409S. Technical Abstract: The role played by micronutrients, such as zinc (Zn), in promotion of optimal physiological function is not well understood. Although some Zn metalloenzymes are postulated to participate in regulation of energy output, there are limited data on the effects of graded Zn intake on RBC carbonic anhydrase (CA) activity and metabolic responses during exercise. Twelve vigorous men, aged 21-28 yr, participated in a double-blind, cross- over study in which Zn was provided as 3 mg/d (low Zn) and 18 mg/d (supplemental Zn) for 9 wk periods with a 6-wk wash-out between dietary periods. Dietary Zn did not affect hemoglobin or RBC count. Serum Zn decreased [13.9 +/- 0.5 (mean +/- SE) vs 11.2 +/- 0.5 micro mol/L; p<0.01] and Zn balance or retention declined (1.43 +/- 0.48 vs 0.23 +/- 0.28 mg/d; p<0.01) with Zn restriction. Peak oxygen uptake, carbon dioxide output and respiratory exchange ratio decreased (p<0.01) during ergocycle exercise when dietary Zn was low. Peak ventilatory equivalents for oxygen and carbo dioxide increased (p<0.05) with Zn restriction. Total CA, and specifically CA-I and CA-II, activities decreased (p<0.05) with low Zn intake. These findings indicate that low dietary Zn, in amounts consumed by some endurance athletes, are associated with significant reductions in erythrocyte CA activity and result in impaired gas exchange and energy production during peak exercise.