milk thistle glutathione pubmed Silymarin”, a Promising Pharmacological Agent for Treatment of Diseases A review of therapeutic potentials
Description
They suppress mineral absorption too, including zinc

doi: 10.1261/rna.7105504 34 HarmanD

Hair, nails, and skin: differentiating cutaneous manifestations of micronutrient deficiency

They correspond to two different documented protocols and per-dose amounts (150 mcg vs 2.5 mg)
