Arrowroot has 7g of carbohydrates per Tbsp and negligible fiber. Arrowroot is indeed a root, so should not have any impact on your grain allergy. You mix it with water - just like cornstarch - to use it as a thickener.

Another thickener is guar gum which is made from the seeds of the cluster bean plant. The plant grows in the Southern US.

My fovourite way to thicken soups, stews and gravies is well cooked, pureed cauliflower. It doesn't add much taste and provides body.

Karen