Antioxidant additives to foods and beverages are important marketing tools. However, little evidence exists on the bio-availability of such antioxidants. Strenuous exercise is expected to induce reversible oxidative stress in healthy volunteers. This is expected to lead to a decrease in antioxidant levels and an increase in lipid peroxidation levels and the Oxidative Stress Ratio. By measuring the ability of an ingested antioxidant to decrease the exercise-induced oxidative stress, information of its bio-availability can be obtained. Therefore an exercise protocol able to consistently induce oxidative stress can be a valuable tool in antioxidant efficacy and bio-availability studies. For this dissertation three different exercise studies, the First, Second and Third Exercise Study were undertaken to investigate the effect of strenuous exercise on plasma and salivary oxidative stress parameters in healthy volunteers. The DPPH Assay was employed as a measure for total antioxidants in plasma and saliva and the TBARS Assay was used as a measure of plasma lipid peroxidation. The Oxidative Stress Ratio, a combined value for the DPPH and TBARS markers was calculated from these values. Some sports physiology parameters were also measured. The possible use of two markers of protein carbonylation as an indication of oxidative stress following exercise was also investigated. They were a spectrophotometric assay, the DNPH Assay and a Western blot method, the Oxyblot™ method. Not one of the three exercise studies succeeded in modulating the oxidative stress parameters in the expected direction to a statistically significant level. Possible improvements for future studies are discussed and include the prescreening of volunteers to exclude exercise tolerant volunteers.
Dissertation (MSc (Biochemistry))--University of Pretoria, 2007.