Monosaccharides and disaccharides are the two kinds of simple sugars, a form of carbohydrate. In contrast to polysaccharides, which contain three or more sugars and are also known as complex carbohydrates, monosaccharides and disaccharides contain one and two sugars, respectively. Monosaccharides include glucose, fructose, and galactose. Disaccharides, by contrast, include sucrose, lactose, and maltose, and these are made up of two monosaccharides bonded together, such as glucose and fructose or even glucose with glucose. Monosaccharides require the least effort by the body to break down and therefore are digested and subsequently available for energy more quickly than disaccharides.
Carbohydrates are the body’s most immediately available source of energy, the source it relies upon for everything from getting through a workout to fueling the brain. The more complex the carbohydrate — that is, the more sugars it contains — the longer it takes to be broken down in the intestines to its simplest components, monosaccharides and disaccharides. Glucose, a form of monosaccharide, is the body’s preferred energy source, and it is also known as blood sugar. Most carbohydrates, whether disaccharides or polysaccharides, end up in glucose form once broken down in the digestive tract. In other words, a major difference between monosaccharides and disaccharides is that monosaccharides are used immediately for energy, whereas disaccharides must be converted into their monosaccharide components before they are of use to the body.
The foods from which monosaccharides and disaccharides like fructose and sucrose are derived for commercial purposes is another difference between the two. Glucose is found in a large number of living organisms, from plants, to insects, to humans. In commercial food production, however, fructose tends to be the preferred sweetener, as it is sweeter than table sugar and can be made cheaply from corn. High fructose corn syrup, for instance, is a fructose sweetener derived from corn that is found in many sweet foods and beverages like baked goods and soda.
Disaccharides are obtained from a variety of plant and animal sources, sources that naturally contain a combination of monosaccharides. Sucrose, the scientific name for table sugar, is a disaccharide that contains both glucose and fructose. It is typically derived from the sugar cane or sugar beet plants, both of which are vegetables. Lactose, another disaccharide, comes not from plants but from animals as it is the type of sugar found in milk and other dairy products. It is made up of glucose combined with galactose.