Carbohydrate: essential for health
Published: February 20, 2015
The term "carbohydrates" may bring to mind foods such as bread, cakes, crackers, potatoes, pasta, rice and other foods which are commonly termed as "carbs".
However, from a scientifc perspective carbohydrates are a family of organic compounds which contain, in various formulae, carbon (C), hydrogen (H), and oxygen (0).
From a nutritional perspective carbohydrate compounds are considered to be macronutrients and are a source of energy and in some instances fibre.
Various carbohydrates, simple and complex, are components of many foods and beverages which usually also contain other macronutrients: water, protein and fat, and various micronutrients such as vitamins, minerals, and phytochemicals.
The many different carbohydrate compounds are commonly grouped as sugars, starches and fibres. Sugars (monosaccharides and disaccharides) are often referred to as simple carbohydrates, while starches and fibres (polysaccharides) are commonly known as complex carbohydrates.
The majority of carbohydrates have chemical formulae with a ratio of one carbon atom (C) to one water molecule (H2O) = CH2O. Different carbohydrate compounds are composed of differing multiples of this single unit.
Monosaccharides are represented by the chemical formula C6H12O6 (6 x single unit). Nutritionally, there are three important monosaccharides:
These three sugars have the same number of carbon, hydrogen and oxygen atoms, but in different molecular arrangements.
Disaccharides are two monosaccharide units linked together. Nutritionally, there are three important disaccharides: maltose, sucrose and lactose.
- Maltose is composed of two glucose molecules linked together and is a component of starch, a complex carbohydrate.
- Sucrose is naturally found in fruits, and some vegetables and grains, and is composed of one glucose molecule and one fructose molecule.
- Lactose, a major component of milk, is composed of one glucose molecule and one galactose molecule.
Polysaccharides are chains of monosaccharide units linked together. Nutritionally, there are three important polysaccharides:
- glycogen (the storage form of energy in your body and in other animals)
- starches (the storage form of energy in plants)
- fibres which provide structure to the stems, trunks, roots, leaves and skins of plants.
Whitney, E. & Rady Rolfes, S. (2005). Understanding Nutrition. Belmont, CA: Thomson Wadsworth
Gropper, S.S., Smith, J.L. & Groff, J.L. (2005). Advanced Nutrition and Human Metabolism (4thEd.). Belmont, CA: Thomson Wadsworth.