N Acetyl L Cysteine (NAC) is a modified form of cysteine which has been attached to an acetyl group. NAC has been shown to increase levels of the antioxidant glutathione which can be used to help reduce cell damage, speed recovery from injury and aid lean growth. By reducing cell damage, NAC has been linked with slowing the ageing process. N Acetyl L Cysteine is particularly popular amongst those who perform high intensity and endurance based sports due to the fact that it can help reduce muscle damage and promote a healthy immune system. Further to NAC’s ability as an antioxidant, it is also widely used by those looking to maintain or build lean mass. It has been shown to help reduce fatigue during exercise.