Macronutrients
Macronutrients are needed in the body to provide energy as well as for other essential functions.
Different macronutrients provide different amounts of energy:
- 1g carbohydrate provides 4 kcal
- 1g protein provides 4 kcal
- 1g fat provides 9 kcal
- 1g alcohol provides 7 kcal
Carbohydrate
All carbohydrates are compounds of carbon, hydrogen and oxygen and essentially come in two forms - sugars and starch. Carbohydrate is the main source of energy in the diet.
Sugars can be split into two groups
- Intrinsic (sugars found in fruits and vegetables).
- Extrinsic (lactose, the milk sugar found in dairy products and foods such as honey and table sugar).
Starch and non-starch polysaccharides (NSP) are commonly referred to as complex carbohydrates.
- Starch is found in potatoes, bread, rice and pasta.
- NSP (or dietary fibre) is found in fruit, vegetables, beans and whole-grain cereals.
Fibre
Fibre is a mixture of mainly complex carbohydrates such as non-starch polysaccharides, lignin and starches which have become resistant to digestion in the upper gastrointestinal tract. Fibre cannot be digested in the small intestine and passes through to the large intestine, helping the gut to function properly and keeping the digestive system working smoothly. If not enough fibre is consumed, food can stay in the gut too long and cause constipation, which can increase the risk of other gut disorders.
Protein
Protein is made up of amino acids, which are compounds consisting of carbon, hydrogen, oxygen, nitrogen and sometimes sulphur.
Protein is important for growth and for the repair of our body tissues. Protein also helps to keep hair, muscles, skin and nails strong and healthy. Protein can provide energy but is not a preferrred source of energy in the diet.
Fat
Fat provides a concentrated source of energy and also helps to provide warmth and insulation around vital organs of the body. The three main types of fatty acids which make up fats are saturated fat, monounsaturated fat and polyunsaturated fat..
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