Todd,
I don't think you can call charcoal a supplement because it is almost always used in acute care. I would call it a remedy instead. We don't bother with the silly capsules sold in stores as they are too much trouble to break open and the amount needed for benefit is often much more than is reasonable to fiddle with that way. I buy our charcoal in large jars. Charcoal is amazing in its absorptive abilities. Hospitals use it in liquid form for poisoning. For home use it can be used where you need to absorb or draw toxins. This may mean food poisoning or "stomach flu" internally or spider bite or bee sting externally. It really works. 

I've seen a vomiting person, writhing with intestinal pain recover their composure in thirty minutes after one dosage of charcoal taken in water...........

Beth