Answer:
Precursors of glutathione are also called building blocks of glutathione. Precursors of glutathione is more of a medical term, whereas you and I might call them raw materials, ingredients, or building blocks of glutathione.
Glutathione is a beneficial protein in each of your cells. The precursors of glutathione are three amino acids that your body uses to make it: cysteine, glutamine (or glutamic acid), and glycine. Your body needs all three amino acids to make the protein glutathione in your cells.
Cysteine + Glycine + Glutamic Acid = Glutathione (GSH)
Of these three precursors of glutathione, it is hardest to get cysteine from our diet. There is plenty of glycine and glutamic acid in most people's diets today. However, to make matters worse, free cysteine, even if you can get it, is of no value because it is destroyed in our gut.
There is a form of cysteine found in nature, but we don't typically consume it. It is called bonded cysteine, and the body can successfully use this form of cysteine to make glutathione. It's found in raw milk, raw eggs, and raw meat. Due to safety concerns, we don't eat those things today, or enough of them in amounts to make a difference. We used to get it when we drank raw milk. Since pasteurization, raw milk has been very difficult to obtain.
Immunocal is made from raw cow's milk, which is very similar in composition to mother's breast milk. Immunocal is rich in this bonded cysteine to raise your glutathione. Immunocal supplies you with the most difficult of all the precursors of glutathione to obtain.
Immunocal is the most effective, safe, and natural way to raise and sustain your glutathione.
You can order Immunocal here.