As of July 2006, Benefiber has announced that all of their products will no longer contain partially hydrolized guar gum. Benefiber will now be made from wheat dextrin. According to a phone representative at Novartis, the makers of Benefiber, this decision was made to allow for smaller dosages and for a higher profit margin. Benefiber guar gum provided 3 grams of soluble fiber per tablespoon, whereas Benefiber wheat dextrin provides 1.5 grams of soluble fiber per teaspoon (there are three teaspoons in one tablespoon).
I do not know how wheat dextrin compares to guar gum as a soluble fiber supplement for Irritable Bowel Syndrome. I would not assume that the wheat dextrin in Benefiber is safe for people with wheat allergies or gluten intolerance disorders such as celiac.