They are not necessarily impure, but the route-of-administration science does not support the marketing in most cases
Glutathione not only strengthens immunity but also aids in body detoxification
However, three real risks exist: reduced therapeutic effect (dangerous for diabetes management), potential contamination in older opened vials, and possible immunogenic responses from aggregated peptides
ONeill, Comparison of the total oxyradical scavenging capacity and oxygen radical absorbance capacity antioxidant assays, J
While not classified as a controlled substance, it is regulated differently for research, therapeutic, and athletic contexts
[PubMed] [Google Scholar] 30.Maranon G, Munoz-Escassi B, Manley W