I've had IBS for 20 years. I have learned which foods to avoid:
most raw fruits and vegetables
(these may vary by individual)
I supplement with a variety of enzymes (Beano, Lactaid, and Fast Food Enzymes) which seem to help.
I eat six to eight times per day with no problems, except bloating in the late afternoon and evening. And this is probably from Surge.
Good luck to your friend.