What is a Carbohydrate?



What is a Carbohydrate? Carbohydrates, as the name suggests, are compounds consisting of carbon, hydrogen and oxygen. The common abbreviation for carbohydrates is therefore CHO. CHOs contribute a substantial proportion of energy to the daily diet – the brain relies almost exclusively on CHO to function, and the other tissues, nerves, and muscles use CHOs for a significant proportion of their energy.

CHOs are broken down to monosaccharides in the mouth to a small degree, but mainly in the small intestine. Monosaccharides are the basic units, or building blocks of CHOs; glucose being the most well known of the three. The other two monosaccharides are fructose (commonly found in fruit) and galactose (occurring as part of the disaccharide lactose).

Disaccharides are made when two monosaccharides join together: Maltose = glucose + glucose
Sucrose = glucose + fructose
Lactose = glucose + galactose

Polysaccharides are linked branched chains of monosaccharides (e.g. starch).

It is from the above chemical explanations that the well-known definitions of simple and complex CHOs came about. Monosaccharides and disaccharides were classified as simple sugars and were thought to be non-nutritious, very sweet and could cause a fast rise and fall in blood glucose and insulin levels, and be a large contributor to dental issues. Complex carbohydrates (starches) were thought to be far more nutritious, and would create a more sustained rise and fall in blood glucose and insulin levels.

Foods defined as Complex Carbohydrate-rich

  • Bread (e.g. multigrain, wholemeal)
  • Breakfast cereals
  • Rice, pasta, noodles
  • Potato, sweet corn
  • Dry biscuits
  • Legumes (e.g. red kidney beans, soy beans, baked beans)
  • Grains including cous cous, barley and oats

    Foods defined as Simple Carbohydrate-rich

  • All types of sugar
  • Honey, golden syrup
  • Jam, marmalade
  • Fruit (e.g. canned, fresh, dried)
  • Jelly
  • Soft drinks and cordials
  • Sugar-based confectionery
  • Dairy products


    For more detail on carbohydrates, click here for an insight into the Glycaemic Index.
    For a list of complex carbohydrates more specific to active individuals and athletes, click here.

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