Carbohydrates: What are they?

Carbohydrate

Both starches and sugars are carbohydrates.  You may also come across carbohydrates described as refined and unrefined, simple and complex.  Fibre is also a carbohydrate which is important for our health, although we cannot digest it.  Carbohydrates seem to have fallen out of fashion in the last few years, with low-carb diets becoming popular.  But carbs should be an important part of our diet.

When carbohydrates are digested, they are broken down into simple sugars.

Starch

Starch is a polysaccharide (meaning many sugars) made up of long chains of sugar molecules called maltose.  Our digestive system breaks these chains, releasing the maltose which is further broken down into glucose.  Starch is also known as a complex carbohydrate.  A refined carbohydrate is a starch that has had some or all of the naturally occurring fibre removed in processing, such as white bread.  An unrefined carbohydrate has been processed less, and contains more fibre and other nutrients, such as wholemeal bread.   Foods containing starch include rice, potatoes, bread, pasta, cereals, bananas, root vegetables, beans and pulses.

Sugar

Sugar is a simple carbohydrate, which is officially called a saccharide.  There are the disaccharides: sucrose (table sugar), maltose (found in cereals such as wheat) and lactose (found in milk).  These are broken down into monosaccharides: lactose becomes galactose and glucose, sucrose becomes fructose and glucose, and maltose is two glucose molecules stuck together so it simply becomes glucose.

Fructose and glucose are found naturally in vegetables, fruits and honey.  Sucrose, also known as table sugar, is made from sugar cane or sugar beet and is often added to drinks and foods.  This is known as added sugar, as it isn’t part of the natural food, or as extrinsic sugar.

Sugar can be classified as Extrinsic or Intrinsic sugar.  Intrinsic sugar is found incorporated in the cells of plants.  Extrinsic is not, and includes all types of table and sugar we use to cook with (for example caster, granulated, icing, Demerara and brown), molasses, treacle, syrup, agave nectar and honey.

The sugar in milk appears under the intrinsic category as a special case, and the sugar in fruit juices appears under extrinsic.

Too much sugar can lead not only to dental problems, but is also linked with obesity and its many related diseases.  Sugar that we do not need can be changed into fat and stored in our bodies.

How much sugar is too much?

The UK government recommend not exceeding 10% of your total energy on extrinsic sugar.  For an average intake of 2000 calories, that would be 200 calories maximum for extrinsic sugar – or 10 to 11 teaspoons of table sugar.  You might think eating 10 spoons of sugar would be quite difficult, but have a look at these common foods and drinks:

When cutting down on sugar, remove processed foods as these often have added sugar.  Fruit contains sugar, but it also contains lots of other great nutrients plus fibre, so is much better if we need a sweet treat.  Apart from some small amounts of nutrients in natural sources of extrinsic sugars such as honey and molasses, most added sugar calories are empty – just calories and nothing else.