Gum arabic
Gum arabic is a complex polysaccharide and soluble dietary fibre that is generally recognized as safe for human consumption. An indication of harmless flatulence occurs in some people taking large doses of 30 g or more per day. It is not degraded in the intestine, but fermented in the colon under the influence of microorganisms; it is a prebiotic (as distinct from a probiotic). No regulatory or scientific consensus has been reached about its caloric value; an upper limit of 2 kcal/g was set for rats, but this is not valid for humans. The US FDA initially set a value of 4 kcal/g for food labelling, but in Europe no value was assigned for soluble dietary fibre. A 1998 review concluded that "based on present scientific knowledge, only an arbitrary value can be used for regulatory purposes". In 2008, the USFDA sent a letter of no objection in response to an application to reduce the rated caloric value of gum arabic to 1.7 kcal/g.