Now Supplements, Nac (N-Acetyl Cysteine) 600 mg With Selenium & Molybdenum, 100 Veg Capsules E-Retailer Product Description  N-Acetyl Cysteine (Nac) Is A Stable Form Of The Non-Essential Amino Acid Cysteine. It Is A Sulfur-Containing Amino Acid That Acts As A Stabilizer For The Formation Of Protein Structures And Is Also Necessary For The Formation Of Glutathione.* Molybdenum And Selenium Are Essential Trace Minerals That Facilitate The Production Of Several Important Enzymes.* Take 1 Capsule Twice Daily. Black Speckling May Occur Over Time After Package Is Opened, But Product Is Safe To Consume. Nac Is A Sulfur-Containing Amino Acid So An...