Also several years years ago I met a globally recognised scientist in the field of anti-oxidants, from Emory University in Atlanta.
He explained to me how much of his research funding was obtained. This was by parties with vested interests giving him money to find almost "anything" positive ( for marketing purposes ) and specifically and contractually told not to report on ANY negative effects.
He told me to forget about supplements in general unless rigorous medical testing uncovered something distinct that I was lacking.
I will go further. He told me that as far as he was concerned, glutathione was the exception to the rule. But, he told me even that is dodgy ground because evidence of "significant and meaningful" bioavailabilty was thin on the ground. His answer? Eat plenty of cysteine containing foods including anything green.