Xanthan Gum is a common food additive used as a thickener in salad dressings and other processed food products. According to Bob's Red Mill, It is made from a tiny microorganism called Xanthomonas campestris and is a natural carbohydrate.
This off-white fine powdered gum can be used to making breads and baked products for people with allergies to gluten. It should be noted that some people report allergies to this gum product so those people should read food labels carefully. While this product is mostly used by the food industry consumers can purchase retail-sized quantities of xanthan gum from sources like Amazon.com Xanthan Gum Gluten Free or directly from Bob's Red Mill.
While technically xanthan gum does contain about 7g of fiber per tablespoon, the USDA does not consider it "beneficial dietary fiber” so most sellers of the productive have updated their labels to show zero grams of fiber. It is simply considered a "non-digestible carbohydrate"