Food Data Chart - Carbohydrate

Sugars and starches in food are sources of energy. Australians obtain 20 to 60 per cent of their total dietary energy from carbohydrate. Cellulose and some related substances are not used by our bodies as a significant source of energy. Nevertheless, these components are very important as, together with other indigestible substances, they constitute dietary fibre. The role of dietary fibre is discussed on Chart 3.

SUGARS

The main sugars in food are sucrose, glucose, fructose, maltose and lactose. Sucrose is obtained from sugar cane and is usually called 'sugar'. In addition, sucrose (as well as glucose and fructose) is found in fruit, fruit juices and honey. Besides providing energy, sugars also produce the sensation of sweetness. Each sugar contributes the same amount of energy (kilocalories) to our diet regardless of its sweetness. Different sugars are not equally sweet and the degree of sweetness of a food is often not a good indication of the amount of sugars present. For example, as shown in Figure 45, maltose is only half as sweet as sucrose.

FIGURE 45: SWEETNESS OF SUGARS RELATIVE TO SUCROSE

SUGAR RELATIVE SWEETNESS OTHER NAME

Sucrose
Glucose
Fructose
Lactose
Maltose
Sorbitol 1
0.7
1.1
0.4
0.5
0.5 Sugar
Grape sugar
Fruit sugar
Milk sugar
Malt sugar
-

Sugars are widely distributed in foods, particularly processed foods where their sweetness may sometimes be masked or hidden by other ingredients. Often the list of ingredients on the label will give an indication of the relative amount of sugar present. For a fuller discussion on sugars, see Sugars and Health.

The use of non-nutritive or artificial sweeteners can be used to make food and drink sweet without contributing significant amounts of energy. Although there is controversy about their safety, the most widely used artificial sweeteners are saccharin and cyclamate. The label of any food or drink containing these sweeteners must indicate that they are present. An artificial sweetener recently approved by some health authorities is aspartame. It has about the same energy value as sugar but because it is 180 times sweeter, very little needs to be used. The amount of aspartame providing sweetness equivalent to one teaspoon of sugar will only provide one-tenth of a kilocalorie.

STARCH

Starch is the main form of carbohydrate in our food. It is present in a variety of cereals, vegetables and fruit, with major contributions from flour, potatoes and legumes (beans, peas). Starchy foods are usually cooked to improve digestibility and give a more desirable texture and flavour. During the ripening of fruit, starch is changed into sugars, which give sweetness to ripe fruits. In contrast to sugars, starch is often accompanied by significant amounts of other nutrients including dietary fibre. Starch has the same energy value as sugars. Health authorities are in agreement that we should increase our consumption of foods containing starch, such as wholegrain bread, cereals, fruits, vegetables and nuts.

CARBOHYDRATE INTAKE

There is no specific dietary requirement for carbohydrate because energy can also be derived from protein, fat and alcohol. However, a diet that does not contain carbohydrate can lead to muscle breakdown, ketosis and dehydration. This can be prevented by 50 to 100 grams of carbohydrate per day, but levels above this are desirable. Sources of complex carbohydrates, such as starch, are recommended as these often also provide necessary vitamins, elements (minerals) and dietary fibre.