Effect of mate tea consumption on rapid force production after eccentric exercise: a randomized, controlled, crossover study

Effect of Green Tea Supplementation on Antioxidant Status in Adults: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

It is well-established that green tea supplementation has antioxidant properties. However, whether green tea supplementation leads to oxidative stress reduction remains unclear, as clinical investigations on this subject have yielded inconsistent outcomes. Consequently, we aimed to determine the effects of green tea supplementation on oxidative stress in adults. A systematic search of English language publications up to 21 August 2021 was carried out in PubMed, Scopus, Embase, and ISI Web of Science, utilizing pertinent keywords. These searches included randomized controlled trials (RCTs) evaluating the relationship between green tea supplementation, malondialdehyde (MDA), and total antioxidant capacity (TAC) in adults. A random-effects model was used to estimate the weighted mean difference (WMD) and 95% confidence intervals (95% CI). Meta-regression and non-linear dose-response analyses were performed to investigate the association between the dosage of green tea (mg/day) and the duration of the intervention (weeks) with pooled effect size. Sixteen RCTs with seventeen arms including 760 participants met the inclusion criteria. Our results indicated that green tea supplementation had significant effects on TAC (weighted mean difference [WMD]: 0.20 mmol/L; 95% CI: 0.09, 0.30, p < 0.001) and significant heterogeneity between studies (I² = 98.6%, p < 0.001), which was largely related to gender and body mass index (BMI). Subgroup analysis in TAC identified a significant relationship except with low dose supplementation and obese individuals. No relationship between MDA and green tea supplementation was observed in any subgroups; however, meta-regression analysis revealed a linear inverse association between the dosage and significant change in MDA (r = −2117.18, p = 0.017). Our outcomes suggest that green tea supplementation improves TAC and affects MDA based on the dose of the intervention in adults. Future RCTs with longer durations are needed to expand our findings.

The effect of leaf extract supplementation on exercise-induced muscle damage and muscular performance: A systematic review and meta-analysis

This systematic review and meta-analysis investigated the effects of leaf-plant extracts typically used for tea beverages on the level of exercise-induced muscle damage. The meta-analysis was conducted by comparing measures between the leaf-extract supplements (SUPP) and placebo (PLA) conditions at 24 h and 48 h following the muscle-damaging protocols from 19 studies with 416 participants. The results showed that the SUPP condition exhibited significantly lower indirect muscle damage markers than the PLA condition at 24- and 48-h post-exercise (p < 0.05). Furthermore, oxidative stress markers were significantly lower for the SUPP condition than the PLA condition at 24-h post-exercise (p < 0.05), although not at 48-h post-exercise (p > 0.05). In addition, no differences were found for anti-oxidant status at 24- and 48-h post-exercise (p > 0.05) between conditions. Muscle performance measures significantly increased for the SUPP condition than the PLA condition at 24-h post-exercise (p < 0.05), but not at 48-h post-exercise (p > 0.05). These results demonstrate that leaf plant extracts reduces the level of various biomarkers indicative of exercise-induced stress, although its effect on anti-oxidant status remains equivocal. Nonetheless, leaf-plant extracts typically ingested as a tea beverage may be an effective recovery strategy following strenuous exercises.