Disaccharides

Disaccharides Definition

Disaccharides [Greek di = two; sacchar = sugar] are sugars composed of 2 monosaccharides (Chart 1). Disaccharides, along with monosaccharides, are called simple carbohydrates.

Three Common Disaccharides

The three most common disaccharides in foods are sucrose, lactose and maltose.

A Typical Disaccharide Structure

A disaccharide molecule is formed by 2 monosaccharides, joined by a glycosidic bond (Picture 1). The type of a glycosidic bond can determine the properties of certain disaccharides. For example, sucrose, isomaltulose and trehalulose are all composed of glucose and fructose, which are linked by different types of glycosidic bonds.

A disaccharide picture

Picture 1. A disaccharide sucrose composed of
monosaccharides glucose and fructose

Disaccharides Examples

Chart 1. Disaccharides list, calorie value, food sources

DISACCHARIDE	STRUCTURE	ENZYME required for digestion	Kcal/g	FOODS high in disaccharides
Sucrose (saccharose, table sugar)	Glucose + fructose	Sucrase	3.9	Table sugar, molasses, maple syrup, fondant, cakes, candies, chocolate, ice cream, fruits, honey
Lactose (milk sugar)	Glucose + galactose	Lactase	3.9	Milk, ice cream, infant formula, milk chocolate, milk candies, certain pills
Maltose (malt sugar)	Glucose + glucose	Maltase, isomaltase	4	Spelt, kamut, sweet potatoes, barley malt syrup, high maltose corn syrup (HMCS), beer, or produced from corn
Isomaltose	Glucose + glucose	Isomaltase, maltase	<2	Produced during digestion of starch (bread, potatoes, rice…), or artificially produced
Isomaltulose	Glucose + fructose	Isomaltase	4	Sugar cane syrup, honey, or artificially produced
Trehalose	Glucose + glucose	Trehalase	4	Mushrooms, honey, seafood, wine, or artificially produced
Trehalulose	Glucose + fructose	Isomaltase	4	Artificially produced from sucrose

Function

Disaccharides are an energy source; most of them provide about 4 Calories (kilocalories) per gram, just like other carbohydrates. Disaccharides are non-essential nutrients, which means they are not necessary for health or life of human beings.

Digestion and Absorption

In order to be absorbed, disaccharides need to be digested, that is broken down, by intestinal enzymes into simple sugars (monosaccharides), which are then absorbed in the small intestine.

Disaccharide Intolerance

Disaccharide intolerance refers to gastrointestinal symptoms (diarrhea, bloating) caused by poor digestion of disaccharides due to lack of respected intestinal enzymes. Lactose intolerance is common, but intolerances to other disaccharides are rare.