Low-digestible carbohydrates represent a class of enzyme-resistant saccharides that have specific effects on the human gastrointestinal tract. In the small bowel, they affect nutrient digestion and absorption, glucose and lipid metabolism and protect against known risk factors of cardiovascular disease. In the colon they are mainly degraded by anaerobic bacteria in a process called fermentation. As a consequence, faecal nitrogen excretion is enhanced, which is used clinically to prevent or treat hepatic encephalopathy. Low-digestible carbohydrates are trophic to the epithelia of the ileum and colon, which helps to avoid bacterial translocation. Short-chain fatty acids are important fermentation products and are evaluated as new therapeutics in acute colitis. They are considered in the primary prevention of colorectal cancer. The bifidogenic effect of fructo-oligosaccharides merits further attention. Unfermented carbohydrates increase faecal bulk and play a role in the treatment of chronic functional constipation, symptomatic diverticulosis and, possibly, the irritable bowel syndrome. In conclusion, low-digestible carbohydrates may play a role in the maintenance of human digestive health. However, the strength of evidence differs between disease entities.

Legislation is described that impacts on the use of low-digestible carbohydrates in foods. This includes controls on the use of these carbohydrates, mandatory labelling concerned with gastrointestinal effects, nutrition labelling, and nutrition and other claims. Regional differences in approach to legislation have led to inconsistencies in the information that must be provided to consumers, even for the same food products. Also, within regions, different regulations apply to food carbohydrates that may be classified similarly from the physiological perspective. Consistency of food labelling globally and in application to similar carbohydrates would benefit from greater attention to the underpinning science.