European journal of nutrition
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Randomized Controlled Trial
The effect of green tea extract supplementation on exercise-induced oxidative stress parameters in male sprinters.
Although research suggests that antioxidant supplementation can protect against exercise-induced muscle damage and oxidative stress, also delayed post-exercise muscle recovery and hindered adaptation to training were reported in the supplemented athletes. ⋯ Supplementation with GTE prevents oxidative stress induced by RST in sprinters. Furthermore, GTE supplementation does not seem to hinder training adaptation in antioxidant enzyme system. On the other hand, neither prevention of exercise-induced muscle damage, nor an improvement in sprint performance is noted after GTE administration.
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Randomized Controlled Trial
Guanidinoacetic acid loading affects plasma γ-aminobutyric acid in healthy men.
Guanidinoacetic acid (GAA), a precursor of creatine and an innovative dietary agent, activates γ-amino butyric acid (GABA) receptors yet clinical effects of dietary GAA on GABA metabolism are currently unknown. The main aim of this pilot research was to investigate whether GAA loading affected peripheral GABA homeostasis in healthy humans. ⋯ Results indicate that supplemental GAA affects peripheral GABA metabolism, and potentially down-regulates GABA synthesis in peripheral tissues. Possible GABAergic action of dietary GAA adds to the safety profile of this novel dietary supplement.