The role of dietary fibre in human health is a topic of both debate and research. Interpreting evidence is complicated by changes in the definition of fibre. In the UK the Scientific Advisory Committee for Nutrition has recently proposed a definition of "all carbohydrates that are neither digested nor absorbed in the small intestine and have a degree of polymerisation of three or more monomeric units, plus lignin". They have also called for further research into the physiological effects of fibre of the gastrointestinal (GI) tract.