GLOSSARY

Types of Sugars can be classified by chemistry, origin in food or public-health definitions. These categories overlap: a sugar may be a disaccharide, added to a product and counted as free sugar at the same time.

A common classification distinguishes one-unit monosaccharides, two-unit disaccharides, short-chain oligosaccharides and longer polysaccharides. The FAO framework generally places oligosaccharides at 3–9 units and polysaccharides at 10 or more. Some sources use different boundaries, so the convention being applied should be stated rather than assumed universal.

Glucose, fructose and galactose are all monosaccharides, but their transport and processing differ. After absorption, fructose and galactose undergo substantial processing in splanchnic tissues, including the liver, and can contribute to energy supply. A lower immediate blood-glucose response does not make a sugar calorie-free or metabolically inactive.

Normal disaccharide absorption requires the bond between the two units to be split by an appropriate intestinal enzyme, such as lactase for lactose or sucrase for sucrose. Limited digestion of a particular sugar can cause bloating or diarrhoea. It does not establish an inability to use every type of sugar.

Glucose or sucrose does not become a different molecule simply because its origin is natural or added. Practical differences often concern amount, food structure, fibre and accompanying components. Eating whole fruit differs from drinking a large sweetened beverage even when some sugars share the same chemical names.

WHO free sugars include added sugars as well as sugars in honey, syrups, fruit juice and fruit-juice concentrates. Sugars within intact fruit and naturally present milk lactose are outside this definition. Consequently, 'no added sugar' does not necessarily mean 'no free sugars' or 'sugar-free'.

A carbohydrate source is assessed through fibre, food structure, accompanying nutrients, free sugars and the purpose of use. Calling its molecules simple or complex does not by itself establish a healthy or unhealthy choice. A fruit containing simple sugars and a highly refined starchy product can play very different nutritional roles.