Vitamin C supplementation improves blood pressure and oxidative stress after acute exercise in patients with poorly controlled type 2 diabetes mellitus: A randomized, placebo-controlled, cross-over study.

This study aimed to assess the effect of Vitamin C on blood pressure (BP), and subsequently on oxidative stress and nitric oxide (NO) release, following the low-intensity exercise in the patients. This study included 24 patients with type 2 diabetes mellitus (T2D) (age, 53 ± 7 years; hemoglobin A1c, 10.1% ± 0.9%) randomized into two 6-week daily arms based on the consumption of either placebo or 1000 mg Vitamin C. The crossover trial occurred after a 6-week washout. Before and after both supplementation arms, all patients performed cycling exercise at 33% of peak oxygen consumption for 20 min. BP was measured before, immediately, and 60 min after the exercise. Blood samples were drawn immediately before and after the exercise to determine plasma ascorbate, malondialdehyde (MDA), F2-isoprostanes (F2-IsoPs), and NO concentrations. Data showed significant lower BP in the Vitamin C arm when compared with the placebo arm (systolic BP [SBP] P < 0.001 at every time point, diastolic BP [DBP] P < 0.001 except at immediately after exercise, P < 0.05). Plasma ascorbate concentration (P < 0.05 at every time point) and plasma NO (at resting P < 0.001, immediately after exercise P < 0.05) were significantly increased in the Vitamin C arm than in the placebo arm. Plasma MDA (P < 0.05 at every time point) and F2-IsoPs (P < 0.05 at every time point) concentrations were significantly lower in the Vitamin C arm than in the placebo arm. In addition, data showed significantly lower SBP (P < 0.001 at every time point), DBP (P < 0.001 except at immediately after exercise P < 0.05), plasma MDA (P < 0.001 at every time point), and F2-IsoPs (P < 0.05 at every time point) at post-supplementation than at pre-supplementation. Besides, there were significantly higher plasma ascorbate (P < 0.05 at every time point) and NO (at rest P < 0.01, immediately after exercise P < 0.05) concentrations at post-supplementation than at pre-supplementation. This is in contrast to the placebo treatment arm which demonstrated no statistical difference in all outcomes throughout the experiment. This study suggests that 6-week Vitamin C supplementation decreased preexercise and postexercise BPs, possibly due to improved oxidative stress and NO release. However, exercise had no effect on any outcome measures.

Cashew apple juice supplementation enhances leukocyte count by reducing oxidative stress after high-intensity exercise in trained and untrained men.

BACKGROUND: Cashew apple juice (CAJ) was shown to improve immunological mechanisms by regulating a balance between reactive oxygen species and antioxidant concentrations. However, no study exploring the effects of the CAJ and training status on the immune system and oxidative stress induced by exercise. Therefore, we investigated the effects of CAJ supplementation primarily on leukocyte counts and secondary on oxidative stress and cortisol changes after high-intensity exercise in trained and untrained men. METHODS: Ten moderately (endurance) trained (Age = 21.5 ± 0.97 yr., VO2max = 45.6 ± 4.12 mL/kgBM/min) and ten sedentary men (Age = 20.4 ± 2.72 yr., VO2peak = 32.2 ± 7.26 mL/kgBM/min) were randomized to ingest either daily CAJ or a placebo at 3.5 mL/kgBM/day for 4 weeks, with a four-week washout period. Before and after each period, they performed 20-min, high-intensity cycling (85% VO2max), with blood samples collected immediately preceding and the following exercise. Samples were analyzed to determine leukocyte counts, malondialdehyde, 8-isoprostane, and cortisol concentrations. A repeated measures analysis of variance was used to examine the effects of supplement and training status over time with an alpha level of 0.05. RESULTS: There was no interaction between supplement and training status on those variables before and after exercise. However, CAJ raised resting neutrophil counts and exercise-induced leukocyte counts in the trained group (all p < 0.05). Besides, CAJ significantly reduced plasma malondialdehyde concentrations at rest and after exercise and reduced the post-exercise plasma 8-isoprostane concentration in both groups of subjects (p < 0.05). Moreover, CAJ reduced plasma cortisol after exercise in the untrained subjects. CONCLUSIONS: We suggest that 4-week CAJ supplementation can enhance exercise-induced leukocyte and resting neutrophil counts in trained men. The possible mechanism is a reduction in oxidative stress. However, the supplementation did not change the immune responses of untrained men, but it did reduce stress hormone concentrations. TRIAL REGISTRATION NUMBER: TCTR20181127002 Registered 26 November 2018 "retrospectively registered".

Antioxidant effect of Phyllanthus amarus after moderate-intensity exercise in sedentary males: a randomized crossover (double-blind) study.

[Purpose] We aimed to evaluate the effects of Phyllanthus amarus (PA) on oxidative stress and damage, inflammation, and soreness in muscle after a single session of moderate-intensity exercise. [Subjects and Methods] Twelve men randomly participated in 2, three-day phases with a one-week washout period. On the first day, participants consumed two capsules of PA or placebo control (CTL) before 20 min of cycling. They then consumed four capsules on the same day after exercise and six capsules/day for the next two days. Blood samples were obtained before, immediately after exercise and 24 h and 48 h after exercise. The pain tolerance was measured at both legs. [Results] Plasma vitamin C levels in the PA group were higher than those in the CTL group after exercise. At 48 h after exercise, vitamin C levels were higher in the PA group, but those in the CTL group were lower than the pre-exercise levels. However, plasma levels of creatine kinase were increased in both groups after exercise compared with the pre-exercise levels. The neutrophil count was higher immediately after exercise than the pre-exercise levels in the CTL group. [Conclusion] Acute supplementation with PA improves antioxidant status after a single session of moderate-intensity exercise.

Antioxidant and anti-nociceptive effects of Phyllanthus amarus on improving exercise recovery in sedentary men: a randomized crossover (double-blind) design.

BACKGROUND: Phyllanthus amarus (PA) is a herbal plant containing antioxidant compounds that scavenge free radicals. The reduced oxidative stress may decrease muscle damage leading to early recovery from muscle soreness. This study aimed to evaluate the effects of PA powder on oxidative stress, muscle damage, leukocyte counts, inflammation, and muscle soreness after a single bout of high-intensity exercise. METHODS: Twelve men participated in two 3-day phases separated by a 1-week washout in a randomized double-blinded, crossover design. On day 1, randomly divided participants ingested two capsules of either PA (PA group) or placebo (PLA group) 20 min before a single bout of cycling at high intensity for 20 min followed by four capsules (two capsules after lunch and dinner), and six capsules/day for the next 2 days. Blood samples were collected before, immediately after, and 24 and 48 h after the exercise. Pain threshold was measured at the mid-thigh on both legs. RESULTS: Malondialdehyde concentration in the PA group was lower than that in the PLA group (p < 0.05) 48 h after high-intensity exercise. Vitamin C concentration was greater in the PA than in the PLA group (p < 0.05) immediately after high-intensity exercise. Pain threshold in both legs in the PA group was higher than in the PLA group 24 and 48 h after high-intensity exercise. There were no significant differences in creatine kinase, leukocyte counts or inflammation between groups. CONCLUSION: Acute PA supplementation reduced oxidative stress and muscle soreness induced by high-intensity exercise.

Cashew apple juice supplementation enhanced fat utilization during high-intensity exercise in trained and untrained men.

BACKGROUND: Exercise training is known to increase fat utilization during exercise. Diets containing antioxidants and branch chain amino acids (BCAAs) are also reported to have potential effects on fat utilization. Cashew apple juice (CAJ) comprises many nutritional components including vitamin C and BCAAs. This study aimed to investigate the effect of CAJ supplementation on substrate utilization during high-intensity exercise in trained and untrained subjects. METHODS: Ten trained and ten untrained men were randomly supplemented with either placebo (PLA) or CAJ at 3.5 ml/kg body mass (BM) /day for 4 weeks with a 4-week washout between treatments in a randomized cross-over design. Before and after the 4-week supplementations all subjects performed cycling exercise at 85% of maximal oxygen consumption for 20 minutes. At rest, before, and immediately after the exercise, venous blood samples were taken to determine glucose, insulin and lipid concentrations. Expired air was collected during the 20 minutes of exercise to calculate substrate utilization. RESULTS: During the exercise in both trained and untrained groups, there were lower carbohydrate (CHO) and higher fat oxidation rates and contributions to total energy expenditure after the CAJ supplementation compared to the PLA supplementation (p<0.05). These values were greater in the trained group than the untrained group except CHO oxidation rates (p<0.05), which were not significantly different. Moreover, in both trained and untrained groups, resting plasma vitamin C concentrations were significantly higher after the CAJ supplementation compared to the PLA supplementation, without any change after the PLA supplementation. These values were greater in the trained group than the untrained group (p<0.05). There were no significant differences in glucose, insulin or lipid concentrations between the groups' blood samples. CONCLUSION: The findings of this study suggest that CAJ supplementation enhanced fat oxidation during exercise may enhance endurance performance, but specific studies are needed to assess this possibility.