Dietary thiols in exercise: oxidative stress defence, exercise performance, and adaptation

Area of Science:

• Exercise physiology and sports nutrition
• Biochemistry of oxidative stress
• Nutritional biochemistry

Background:

• Excessive aerobic exercise generates reactive oxygen species (ROS), potentially causing cellular damage and fatigue.
• While ROS are implicated in fatigue, they also play a role in exercise adaptations.
• Antioxidant supplements like vitamins C and E have controversial effects on athletic performance and recovery, sometimes blunting training adaptations.

Purpose of the Study:

• To explore the potential of dietary thiol donors to enhance endogenous antioxidant systems in endurance athletes.
• To investigate the ergogenic and recovery benefits of thiol donors, specifically N-acetylcysteine (NAC) and keratin.
• To assess whether keratin, a food-sourced thiol donor, can improve antioxidant capacity without negatively impacting training adaptations.

Main Methods:

• Review of existing literature on ROS, exercise physiology, and antioxidant supplementation.
• Analysis of studies investigating N-acetylcysteine (NAC) as a cysteine donor for augmenting glutathione and reducing oxidative stress.
• Exploration of recent findings on keratin as a potential thiol donor food source for enhancing endogenous antioxidants.

Main Results:

• NAC supplementation has shown potential in improving antioxidant capacity and delaying fatigue in experimental models.
• Concerns exist regarding potential adverse physiological effects of certain thiol donors like NAC.
• Keratin, as a food-sourced thiol donor, presents a novel approach to enhance endogenous antioxidants.

Conclusions:

• Endurance athletes may benefit from strategies that up-regulate endogenous antioxidant systems rather than relying solely on exogenous supplements.
• Dietary thiol donors, particularly keratin, offer a promising avenue for enhancing athletic performance and recovery without compromising training adaptations.
• Further research into keratin's efficacy and safety as a thiol donor for athletes is warranted.