The Effects Of Beetroot-rich Juice Supplementation On Antioxidant Capacity In Recreational Exercisers

Abstract

PURPOSE: To determine the effects of 31-day beetroot-rich juice supplementation on antioxidant capacity in Chinese recreational exercisers. METHODS:60 recreational endurance exercisers (30 males) from China were recruited including 40 youths (18-25 yrs) and 20 middle-aged adults(30-37 yrs). All participants were divided into Beetroot group(B) or Placebo group(P) randomly and then consumed beetroot-rich juice(20 ml) or placebo (Erythritol; 20 ml) two times every day for 31 days. Before and after the intervention, participants completed an exhausting running test (run at 50-55% velocity(V)max for 60 min and then run at 80%Vmax until exhaustion). Venous blood samples were collected before and 30-min after every running test. RESULTS: Before the intervention, there were no significant differences in the baseline levels or post-exercise index of SOD, T-AOC, and MDA between participants of different intervention groups, genders and age groups. After 31-day supplementation of beetroot juice (B group), the SOD activities of young males at rest increased significantly (41.36 ± 6.45 vs. 44.25 ± 6.5 U/ml, p < 0.05), and a significant increase in T-AOC level was also observed in young females (1.18 ± 0.18 vs. 1.35 ± 0.19 mM, p < 0.05). Among middle-aged participants, SOD activities were observed elevating in both genders after intervention (male: 37.15 ± 6.91 vs. 44.95 ± 5.47 U/mL; female: 34.31 ± 6.82 vs. 40.14 ± 2.81 U/mL, p < 0.05). In the placebo(P) group, the SOD activities of different age and gender groups didn’t change. The T-AOC level (1.53 ± 0.16 vs. 1.28 ± 0.19 mM, p < 0.05) and SOD activities(48.83 ± 4.94 vs. 45.2 ± 5.63 U/ml) after the exhausting running test in young participants were higher than those before the intervention. Compared with the P group, the post-exercise T-AOC (1.11 ± 0.23 vs. 0.94 ± 0.15 mM, p < 0.05) and SOD activities (45.41 ± 6.34 vs. 38.14 ± 3.09 U/mL, p < 0.05) of females in the B group were significantly higher. Meanwhile, the MDA level of females in B group after running was significantly lower than in P group (middle-aged: 4.58 ± 0.61 vs. 5.93 ± 0.04 mmol/mL, p < 0.05). CONCLUSIONS:31-day beetroot-rich juice supplementation can improve the whole-body antioxidant capacity of recreational exercisers of different ages and genders, and can reduce the oxidative stress level after exhaustive exercise.