Hydrogen breath testing can be used to test for fructose intolerance. Fructose is a sugar found naturally in fruits, vegetables and honey. It is also used as a sweetener in some soft drinks and fruit drinks. Fructose malabsorption occurs when the body doesn’t take in fructose the right way. Undigested fructose reaches the small and large intestine, naturally occurring bacteria feed off of this excess sugar, and the resulting symptoms of gas, bloating, pain and discomfort occur.