I think anytime fatty food is suggested when involving Meds or supplements it's because cell membranes are lipidsoluble. Lipids readily cross the cell membrane barrier with ease. Lipid soluble Meds need some dietary fat for best absorption. Just because you take it orally doesn't mean it just works in the GI tract only. It can be absorbed and transported throughout the body where needed. Some substances even cross the blood brain barrier which would require it to be a certain size and lipid-soluble.