Chronic and acute effects of hydroxytyrosol on antioxidant status and inflammation at rest and during exercise
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Evidence shows that consumption of a Mediterranean diet can lower the risk of all-cause and cause-specific mortality suggesting that this diet has an overall effect on health. Antioxidants found within olive oil, the primary source of fat in the Mediterranean diet, may be leading contributors to the decreased disease risk. More specifically, hydroxytyrosol (HT), one of the most active and powerful antioxidants found in olive oil, has the ability to increase total antioxidant status and lower levels of lipid peroxidation. In addition to a healthy diet, physical activity decreases the risk of cardiovascular morbidity and mortality; however, aerobic exercise of sufficient intensity or duration can induce oxidative stress. Therefore, the purpose of this study was to investigate the effects of 6 weeks of HT supplementation on antioxidant status and markers of inflammation in healthy, recreationally active males before and throughout acute aerobic exercise bouts. Using a randomized, double-blind, repeated-measures, placebo-controlled design, sixty-one (n=61) participants were randomly assigned to consume a placebo (PLA), low dose of HT (LHT, 50 mg/day), or high dose of HT (HHT, 150 mg/day). Throughout the course of the study, the participants performed four time trial rides (TT1-TT4) on cycle ergometers. TT1 occurred before supplementation, TT2 halfway through the supplementation period, and TT3 and TT4 occurred in the sixth week and final two days of supplementation. Blood was drawn prior to (pre) and just before termination (end) of each time trial to measure markers of antioxidant status and inflammation during exercise. We did not observe significant main effects for treatment on any of the markers for antioxidant status (TEAC) or for markers of inflammation (oxLDL, CRP, 8IP, TNFα, IL-6, IL-10, IL-1β, or IL-1ra). Significant treatment-by-time interactions occurred for CRP, 8IP, and IL-6 although significant treatment differences in these measures were not detected. We conclude that chronic and acute HT supplementation does not improve antioxidant status nor decrease markers of inflammation in this population at rest, during, or following exercise.