NOW is a brand I have really come to trust and I really need this product on the order of my holistic doctor as an anti-oxidant, detoxifying agent, and free-radical scavenger for my thyroid disorder Hashimoto's autoimmune thyroiditis/hypothyroidism. N-acetyl cysteine increases glutathione in the body, which is especially needed and yet is unable to be produced in enough quantities in the body in certain disease states, especially autoimmune diseases and thyroid diseases. I also have prediabetes, and glutathione also is needed as a detoxifying agent for the liver, which is a problem for diabetics as well. I was taking three times a day but it made me nauseous so I started taking one in the am and that was working fine. Lately I tried three times a day again to get full benefit and was careful to take with food, and no problems. This is a high quality product at a reasonable price, as are all NOW products that I have tried. Will keep taking and ordering this product!