One ingredient I like to add to my pemmican from time to time (especially to the cold recipe versions) is oat bran. It mixes in well, does not add a lot of weight, and really gets the fiber content up good. Of course the regular addition of dried fruits and vegetables in my pemmican recipes already helps with the fiber content.

I've also used fenugreek seed along with cumin to give the pemmican an indian flavor. Fenugreek seed is a natural laxative. Very mild, but effective.

Fortunately, even without adding fiber or laxative ingredients, I have yet to encounter a bowel problem from eating pemmican. Not so with the MREs, as other people have already mentioned.