Protected from gastric acid by an enteric-coated capsule
 
Vitamin C, E, B12, folic acid, selenium, zinc and manganese are necessary for an optimal utilization of reduced L-glutathione 

Highly present in the liver, kidneys, pancreas, spleen and eyes, L-glutathione plays important roles
in antioxidant defense, in nutrient metabolism,
in regulation of cellular events (including gene expression, DNA and protein synthesis, cell proliferation and apoptosis, signal transduction, cytokine production and immune response, and protein glutathionylation
Low-protein diet, stress, high physical exertion, reduction diets, taking certain medications and in old age can cause glutathione deficiency.