INFLUENCE OF AN ANTIOXIDANT NUTRIENT FORTIFIED FOOD PRODUCT AND STRENUOUS EXERCISE ON ANTIOXIDANT ENZYME SYSTEMS 176

Abstract

Sixteen healthy adult male subjects 18-34 y of age participated in a double blind placebo controlled trial designed to measure: 1) the effect of the consumption of an antioxidant nutrient fortified food product (VO2 MAX™ Energy Bar [VM-Bar]) on select components of the oxidative defense system, and 2) the effect of a 30 min run at 80% VO2max, then a continuous ramp to exhaustion within 5 min (EX), on these components, prior to, immediately after, and 24 h after EX. Subjects were trained individuals who continued an exercise regimen (20-25 miles of running/wk) during the trial period. Fortification was achieved using a low-fat food bar (VM-Bar) to which ascorbic acid (94 mg), α-tocopherol acetate (43 mg) and a carotenoid mixture, consisting primarily of α- and β-carotene (7.4 mg), were added during the manufacture of the product. The placebo bar (P-Bar) contained no fortification, but was otherwise identical to the test bar in macronutrient composition, taste and appearance. Subjects consumed 2 bars/d of either the VM-Bar or P-Bar for 6 wk followed by an 8 wk washout period and a subsequent cross-over for an additional 6 wk. EX was performed at the beginning and end of each new treatment. Dietary screening criteria excluded applicants who consumed dietary supplements of any kind. Diets were monitored via 3 d food records during each treatment to ensure consistent nutrient intake. Consumption of the VM-Bar was associated with marked increases in plasmaα-tocopherol, ascorbic acid, and carotenoid concentrations. The concept that these changes were functionally significant is supported by the observation that EX-induced increases in the activities of the oxidant defense enzymes, red blood cell and plasma glutathione peroxidase, and superoxide dismutase were lower in subjects consuming the VM-Bar than the P-Bar(p<0.05). We suggest that this lower induction of enzymes indicates a lower level of oxidative stress in the VM-Bar group.