Question about Some Siouan cooking habits.

[Rankin, Robert L]

I'm sitting in on an ethnobotany course this semester, and one of the things that was mentioned was that the Masai and other African tribes who depend almost exclusively on meat and meat products for food mix Acacia bark in with their stew and it has a cholesterol-lowering medicinal effect.  This reminded me of something Mrs. Rowe told me about Kaw cooking.  She said that THEY USED TO PUT THE INNER BARK OF THE ELM TREE IN THEIR COOKING GREASE.  I always figured that they just liked the flavor it imparted, but I'm finding out that it probably had specific and positive medicinal effects.  
 
Have any of the rest of you heard of this habit among other Siouan-speaking peoples?  I suspect Mrs. Rowe was referring to /hiNje $cu$ce/ the "slippery elm", because its inner bark is sort of gooey.  It would also serve as a thickener for meat broth.
 
Bob