Glutathione is such a critical soldier in our line of defense that our bodies make it themselves. We even have mechanisms that recycle and reuse it. But what happens when our toxic Elemental Diet as a Therapeutic Modality: A Comprehensive Review Digestive Diseases and Sciences Springer Nature Link Can Collagen Cause Constipation? Symptoms, Fixes & Safer Use Leucovorin (also called folinic acid) is a folate analog and chemoprotective agent. It's used to rescue healthy cells from the toxic effects of high dose methotrexate, to enhance the effectiveness of fluorouracil (5 FU)