Gum Arabic (Acacia gum, INS 414: E414) is extensively used as a food additive, but there is no regulatory or scientific consensus about its calorific value. It is a complex polysaccharide, primarily indigestible to both humans and animals, not degraded in the intestine, but fermented in the colon under the influence of microorganisms. Despite a range of animal studies, there are no usable data for humans which can quantify the utilizable energy of Gum Arabic. Estimates in the literature from animal experiments vary from 0 to 4 kcal/g. After certain allowances are made for the energy losses from volatile and gaseous fermentation products, an upper level of 2 kcal/g for rats has been set. The situation in man is demonstrably different, with greatly reduced amounts of such products, and the need to adapt for varying periods before Gum Arabic is attacked by colonic bacteria. In the absence of an agreed scientific assignment, the FDA in the USA insist upon 4 kcal/g in nutritional labelling, whereas in Europe, no value has been assigned to soluble dietary fibre, such as Gum Arabic. This review argues that based on present scientific knowledge only an arbitrary value can be used for regulatory purposes.