Salivary Total Antioxidant Capacity of Sportive Adolescents-The Effect of Antioxidant Vitamin Intake with Usual Diet and Physical Exercises.

Background: The body requires effective antioxidant defense mechanisms to counter the effect of oxidative stress. The aim of the study was to evaluate the postprandial effect of antioxidative vitamin (C, E and β-carotene) consumption during breakfast and of aerobic exercise on salivary total antioxidant capacity (TAC). Methods: Fifty-one healthy male adolescents were examined (13-18 years; 15.4 ± 1.6). Dietary interviews including vitamin C, E, and β-carotene intake were performed twice, once on the examination day and again the day before. Salivary TAC was assessed using the DPPH method (2.2-diphenyl-1-picryl-hydrazyl) and expressed as % of free radical reduction. Saliva samples were assayed at three subsequent time-points: fasting (DPPH 1), after a meal-breakfast-(DPPH 2), and after aerobic exercise training (DPPH 3). Results: DPPH 2 was higher than DPPH 1 (16.8 ± 7.5 vs. 14.9 ± 7.2% of reduction; p = 0.03), and no differences were noted between DPPH 2 and DPPH 3 (16.8 ± 7.5 vs. 16.3 ± 6.5%; p > 0.05), nor between DPPH 1 and DPPH 3. Subjects with higher BMI demonstrated higher values of DPPH at all time-points of the study (p < 0.05). In turn, neither the DPPH values nor the changes in DPPH were related to weekly exercise-related energy expenditure (p > 0.05). No singular DPPH index was associated with the level of vitamin E or β-carotene intake with meals on the day before the study; however, DPPH 1 (rho = -0.38; p < 0.01) and DPPH 2 (rho = -0.45; p < 0.001) negatively correlated with vitamin C intake on the day before examination. Conclusions: In physically active adolescents, daily vitamin C consumption decreased salivary TAC, and the consumption of antioxidant nutrients/vitamins as part of a regular breakfast directly enhanced the antioxidant capacity of saliva; nevertheless, subsequent physical exercise had no detectable impact.