NAC Powder, Watermelon 600 mg by Trace Minerals Research

NAC is for adults who want to support their body's own glutathione, the main antioxidant inside cells. It is a reasonable pick if your Total Glutathione has tested low, if you are older or train hard, or if you want support for your airways. A powder suits people who dislike swallowing capsules, though NAC has a sulfur taste that flavoring only partly covers. If you feel well, eat enough protein and have no particular reason to take it, the case is weaker.

N-acetyl L-cysteine is a stable form of the amino acid cysteine. Cysteine is usually the ingredient in shortest supply when the body makes glutathione, so providing it helps cells keep their glutathione topped up. That matters most in the liver, which uses glutathione to neutralize reactive by-products and to process many compounds. NAC also loosens mucus by breaking the bonds that make it thick, which is why it has a long history of use in respiratory care.

Each scoop (2.5 g of powder) provides 600 mg of N-acetyl L-cysteine, with 5 calories and 1 g of carbohydrate. The tub holds 30 servings. The label's suggested use is 1 scoop mixed with 4–8 oz of water daily. It is sweetened with xylitol and steviol glycosides and flavored with natural watermelon flavor. Taking it with food cuts down on the nausea NAC can cause. Keep the tub away from dogs, since xylitol is toxic to them.

The label is for adults only and names one medicine: nitroglycerin. NAC can strengthen the effect of nitroglycerin and related nitrate medicines for angina and bring on low blood pressure and a severe headache, so do not combine them unless your cardiologist agrees. NAC may also slow blood clotting slightly: if you take a blood thinner or have a bleeding disorder, check first, and tell your surgeon before any operation. People with asthma should start cautiously, since NAC occasionally sets off wheezing. If you are pregnant or nursing, the label says to consult your physician.

Most people feel nothing in particular, and that is expected. If you are tracking Total Glutathione, retest after 8 to 12 weeks of steady use. The common side effects are nausea, loose stools and heartburn, usually settled by taking it with a meal. Compared with swallowing glutathione itself, which is absorbed inconsistently, NAC is the better-studied way to support the body's own production. Capsules avoid the taste; a powder makes the amount easier to adjust with your clinician.