I have been taking Dr. Rob Keller's Glutathione formula for over 20 years. I had been diagnosed with Hepatitis C following a blood transfusion during surgery in 1978. I took glutathione for at least the last 20 years of my infecion. I know this formula boosted by immune system over the many years I was infected with Hep C because during that time I developed several non-melanoma skin cancers and they always responded to the glutathione. If I upped the dosage, these lesions dried up and disappeared. So I knew my immune system was being enhanced by the glutathione. I am quite sure that it was a critical part of my remaining reasonably healthy throughout my illness. I was cured of Hep C in 2015 and still take Dr. Rob Keller's formulation to boost my immune system, which has been compromised by so many years of a chronic infection. Glutathione is a very difficult substance for the body to absorb, but Dr. Rob Keller's unique formulation is the key to its working so well.