Fructose, often described as ‘fruit sugar’, is a monosaccharide found naturally in all fruits, most vegetables, honey, and is commonly added to food and drink as a sweetener (as fructose or high-fructose corn syrup). Fructose is thought to be absorbed in the small intestine by facilitated diffusion (through a luminal transporter) and paracellular transport (with glucose). In paediatric patients, there is growing evidence that a significant percentage of children with recurrent abdominal pain of childhood (RAPC) have fructose intolerance.
Fructose shouldn’t be confused with fructans, which are chains of fructose molecules naturally occurring in a variety of vegetables and grains. Humans cannot digest fructans, so they are instead fermented by bacteria in the gut. While this can provide health benefits to some, it may cause gastrointestinal distress in others.