The products of digestion normally travel from the small intestine to the liver where they are broken down further, cleaned of any microbes, and sent to all the body cells via the hepatic portal vein and inferior vena cava. When Fructose Malabsorbers consume fructose and HFCS, less fructose makes its way to the liver. It becomes concentrated in the small and large intestines and is known to contribute to abdominal gas, bloating, pain and discomfort. 
In Fructositis disease, fructose that is not absorbed is thought to become reactive and contribute to the formation of dietary protein resistant fragments that contribute to asthma and auto-immune reactivity.
Under normal conditions, for example in non-malabsorbers, fructose is metabolised primarily by the liver. While a few other body tissues including sperm cells and some intestinal cells have the enzymes necessary to use fructose directly, the liver contains most of the body's fructokinase. Glucose metabolism differs markedly from fructose and tends to pass through the liver to be metabolised anywhere in the body. In non-malabsorbers, excessive fructose consumption may contribute to the development of non-alcoholic fatty liver disease.