Foods that have been thickened help swallowing impaired patients by converting the food or liquid to a consistency ranging from a heavy syrup to mashed potato or pudding. The food becomes dense and cohesive, which eliminates the problem of thin pureed food or drink running down the throat and into the lungs.  See   5 Levels Difficulty In Swallowing

Important: Before using any food thickeners, please consult with your physician and/or speech pathologist. A swallowing study may be warranted, covered by Medicare, and identify the appropriate thickener.  Below are a few of the products offered commercially.  Typically, you can ask your local Pharmacist about the commercial Food Thickners they can purchase for you by the case.  Buying by the case is usually cheaper then buying one can at a time.