Are there any concerns or considerations?

Current use of antioxidant supplements

Mega dosing with exogenous antioxidants can potentially inhibit adaptations to exercise.⁶ It is important to establish an athlete’s current use of antioxidant supplements and consider ceasing when supplementing with NAC for prolonged periods (i.e., during training camps).

Side effects of NAC

Several unwanted side effects have been reported with the use of NAC. It is recommended that when using NAC, athletes are educated on the potential side effects and complete the questionnaire below daily to track and manage any occurrences (Figure 1). If side effects do occur, quercetin may be used as an effective alternative during periods of intensified training or altitude camps. However, other ergogenic aids (i.e., bicarbonate, caffeine) should be considered if NAC is being used for acute performance benefits.

Figure 1: N-Acetyl Cysteine Health Questionnaire

Please grade any reactions that you experience following consumption of the supplement. Mark only one square.

Habitual use is not recommended

NAC is not recommended for habitual use. Rather, an increased dietary intake of antioxidant rich foods should be used to improve the oxidantantioxidant balance in athletes.