can glutathione cause gas Stomach Pain? What You Should Know – CYMBIOTIKA Toxicity of Glutathione-Binding Metals: A
Description
There havent been any serious or adverse effects reported from glycine use yet, so at the moment, it appears to be a supplement that is safe to use every day

Allameh A & ziglar T

Clin Pharmacokinet 2009

Additionally, trials of oligonucleotide therapeutics and some small-molecule NNMT inhibitors in vitro and in preclinical animal models have validated NNMT as a promising therapeutic target to prevent or treat obesity and related T2D, but currently, clinical trials have not yet been reported
