250g - & Non-GMO Antioxidant Boost. N-Acetyl L-Cysteine (NAC) is a stable, effective form of the amino acid L-Cysteine, renowned for its incredible health benefits. This pure powder is a powerful antioxidant that not only supports your body's defense against oxidative stress but also plays a crucial role in maintaining optimal glutathione levels, known as the body’s master antioxidant.