Understanding Simple Sugars and Their Role in Nutrition

Simple carbohydrates, naturally occurring as simple sugars, are found in foods like fruits, milk, and others. These sugars are important for quick energy. Carbohydrates from plants can also be processed to create sugar products like table sugar or corn syrup, which are commonly used in various foods.

There are two main types of sugars: monosaccharides and disaccharides. Monosaccharides, the simplest sugars, include glucose, fructose, and galactose. Disaccharides form when two monosaccharides bond, releasing a water molecule. This glycosidic bond is key to the structure and function of disaccharides in our diet.

Sucrose, or table sugar, is the most common disaccharide, made of glucose and fructose. When eaten, enzymes in the digestive system break it down into these two components. The body can convert fructose into glucose, so one molecule of sucrose ultimately provides two glucose molecules for quick energy.

Three important disaccharides in nutrition are maltose, sucrose, and lactose. Maltose, found in germinating grains, consists of two glucose molecules. Sucrose, the familiar table sugar, is used in cooking for its sweetness and solubility.

Lactose, or milk sugar, is present in milk and dairy products, made of glucose and galactose. It is the least sweet and soluble of the sugars, explaining why milk tastes less sweet. Some people lack the enzyme lactase to digest lactose, leading to lactose intolerance.

Recently, concerns have grown over excessive consumption of refined sugars and their effects on health. High intake of added sugars is associated with obesity, type 2 diabetes, and heart disease. Health experts now advise limiting added sugars and choosing natural sources like fruits and dairy for a balanced diet.
Understanding Simple Sugars and Their Role in Nutrition

Simple sugar of monosaccharides

The two main types of sugars are monosaccharides and disaccharides. Monosaccharides consist of a single sugar molecule.

Monosaccharides may contain from three to nine carbon atoms although most of them contain five or six. A three carbon monosaccharide is called a triose; one containing four carbons is called a tetrose; five, a pentose; six, a hexose; seven, a heptose; eight an octose and nine a nonose.

α- D -glucose

*Pentoses (Arabinose, ribose, xylose) The pentose sugars, deoxyribose and ribose, are essential components of the genetic material DNA and RNA. E.g. glucose and fructose: (C6H12O6); arabinose and xylose: (C5H10O5).

Arabinose is found in gums and when several arabinose molecules are joined together, a pentosan formed.

*Hexoses
-Aldohexoses – galactose, glucose
-Ketohexose - fructose
 All hexoses have the same chemical formula C6H12O6, but slightly different structures. In nature, only fructose and glucose occur in free form. Galactose joined with glucose forms the disaccharide lactose.

Glucose is a hexose. Octoses and nanoses are quite rare. Glucose, the main source of energy for body cells, is found in most sweet fruits and in blood.
Simple sugar of monosaccharides