There are many different terms when it comes to carbohydrates and sugars.
- Carbohydrates. Dietary carbohydrate include sugars, starches and fibres.
- Sugars. The term “sugars” describes all mono- and disaccharides. Sugars are found naturally in fruits, vegetables, and milk products, or added to foods and beverages.
- Sugar. The term “sugar” is used to describe sucrose specifically.
- Alternative sweeteners. "Sugars" does not include high-intensity sweeteners, sugar alcohols, or polydextrose.
Carbohydrates are an important source of food energy. Starches, sugars, and fibre are the most common types of carbohydrate in the diet.
According to chemical composition and the number of single sugar units bound together, dietary carbohydrates are grouped into three categories:
- Sugars (1-2 units);
- Short-chain carbohydrates or oligosaccharides (3-9 units); and
- Polysaccharides (≥10 units).
The simplest carbohydrates are monosaccharides (single sugar units) such as glucose, fructose and galactose. Other carbohydrates are composed of multiple monosaccharide units. Sugars (i.e. mono-saccharides and disaccharides), oligosaccharides and starch can be broken down to single monosaccharide units by enzymes in the small intestine. They all provide 4 Calories per gram to the body. Fibres, on the other hand, cannot be broken down to single units. They are instead either fermented in the large intestine by microflora into other substances (e.g. short-chain fatty acids) or secreted out in feces intact. The fermentable fibres provide 2 Calories per gram to the body whereas infermentable fibres provide 0 Calories.
The compositions of common digestible carbohydrate are shown in the figure below (*Fru=fructose; Glu=glucose, Gal=galactose).
The term "sugars" or “total sugars” refers to all monosaccharides and disaccharides naturally occurring or added to foods. Examples of monosaccharides are glucose and fructose and examples of disaccharides include sucrose, lactose and maltose. Sugars occur naturally in foods such as milk (lactose) and fruits and vegetables (glucose, fructose and sucrose). Sugars such as sucrose, honey, glucose and many others are also added to foods to provide sweetness and other important functional properties.
“Free sugars” is an emerging term appearing in recent government reports and dietary guidelines. It is defined by the World Health Organization and the UN Food and Agriculture Organization as sugars that are added to foods by the manufacturers or consumers, as well as naturally present in honey, syrups and fruit juices.
“Sugar” is sucrose, a carbohydrate found in every fruit and vegetable and is the major disaccharide in most diets. All green plants produce sucrose through photosynthesis, the process by which plants transform sunlight into their food and energy supply. Some plants, such as sugar cane and sugar beet, accumulate high levels of sucrose and as such are used as commercial sources of sugar.
Sucrose is a disaccharide, made up of one unit of glucose and one unit of fructose. It is present in honey, maple syrup, fruits, berries, and vegetables, and is also added to food products in granular or liquid form.
In Canada, the Food and Drug Regulations prescribe the standard for sugar as the "food chemically known as sucrose". It has a specific compositional standard; i.e. must "contain not less than 99.8% sucrose". For food labelling purposes, sugar is considered the "common name" of the food and must meet this standard. When listed in the ingredient list of a food, different types of sugar can be listed; for example, sugar, liquid sugar, invert sugar or liquid invert sugar. Compositional standards for other types of sugar are also defined in the Regulations, including icing sugar and brown sugar. All of these products are derived from sugar cane or sugar beet.
For more detailed information on the labelling of sugars-based ingredients, visit our page on Nutrition Labelling and Claims.
“Sugars” does not include high-intensity sweeteners, sugar alcohols, or polydextrose.
- High-intensity, zero-calorie sweeteners are food additives, and common examples include aspartame, acesulfame-potassium, and sucralose.
- Sugar alcohols are food additives, and common examples include maltitol, sorbitol, and xylitol. Sugar alcohols are not completely absorbed in the small intestine and therefore contribute 0.2-3 Calories/gram compared to sugar’s 4 Calories/gram, however overconsumption can lead to bloating, diarrhea, and flatulence.
- Polydextrose is a food additive derived from dextrose (glucose), which is typically used to provide bulk in foods without adding sweetness. It contributes 1 Calorie/gram.
For more information, additional resources include:
- Infographic - Learning About Sugars Labelling: New Nutrition Information
- "Sweeteners" by the Canadian Food Inspection Agency
Food and Drug Regulations, Department of Justice Canada
Cumming JH and Stephen AM. Carbohydrate Terminology and Classification. European Journal of Clinical Nutrition, 2007, 61:Suppl1: S5-S18.
Report of a Joint FAO/WHO Consultation. 1997. Carbohydrates in Human Nutrition.