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Your body not only needs protein, it also needs a sufficient quantity of each of the amino acids, the building blocks of protein. There are 21 amino acids, nine of which are essential in the diet since the body cannot manufacture them.

Amino acids are needed to manufacture the structural components of muscle tissue, enzymes, haemoglobin, antibodies, hormones and transport proteins. They are therefore needed for strength, to build and maintain muscle, maintain immune function, to aid recovery and, in younger athletes, protein is also essential for growth and development.

Protein is not an efficient source of fuel during exercise, but when too little energy is available from carbohydrate and fat, amino acids will be used as energy. In this situation, amino acids are broken down to form glucose and nitrogen. The nitrogen waste produced must not be allowed to accumulate in the body as it is toxic and it is therefore converted to urea and excreted from the body by the kidneys.

One of the biggest myths is that large amounts of protein are required to build muscle. Your muscles can only use a limited amount of protein for growth, provided there is enough carbohydrate to fuel the strength-training required for your muscles to grow. Any excess protein will be broken down for energy and excreted as urea, although excessive protein intake may increase total calorie intake, increasing the chances of weight gain. The process of breaking down amino acids also necessitates the excretion of water and so excessive intakes of dietary protein may affect fluid balance. A consistently high protein intake may also contribute to kidney disease, gout and arthritis.

Vary your protein intake to provide a selection of different nutrients.

There is no storage form of protein, but the body is continually synthesizing protein from the pool of amino acids within cells and then breaking them down again.

FOODS AND PORTION SIZES PROVIDING 10G PROTEIN

▪ 50g (1.7 oz) grilled fish (cooked)

▪ 50g (1.7 oz) tuna, salmon, pilchards

▪ 35g (1.3 oz) lean beef, lamb, veal or game (cooked)

▪ 40g (1.3 oz) chicken or turkey (skinless, cooked)

▪ 50g (1.7 oz) ostrich (cooked)

▪ 2 small or 1 large chicken egg

▪ the whites of 3 large eggs

▪ 70g (2.3 oz) cottage cheese

▪ 30g (1 oz) low-fat cheese

▪ 200ml (¾ cup) low-fat fruit yoghurt

▪ 300ml (1¼ cups) low-fat milk (cow or soy milk)

▪ 30ml (2tbsp) low-fat or skim milk powder

▪ 250ml (1 cup) liquid meal replacement (made up with skim milk or water)

▪ 160ml (⅔ cup) cooked lentils

▪ 125ml (½ cup) cooked soya beans

▪ 200ml (¾ cup) baked beans

▪ 40ml (3½tbsp) nuts*

▪ 60ml (5tbsp) sesame seeds

▪ 200ml (¾ cup) cooked soya mince

▪ 120g (4 oz) raw tofu

▪ 125ml (½ cup) hummus*

▪ 70g (2.3 oz) Quorn (textured vegetable protein)

* These foods have a high fat content

Foods in portion sizes of 10g protein. See the table on p11 (Sizing It Up) on how to estimate the size of portions.

However, extra protein may be needed after training, a competition or match and especially so if you have experienced any muscle or tissue damage. Muscle damage also interferes with the storage of carbohydrate as glycogen, so together with the extra protein you should also increase your carbohydrate intake (see Recovery Nutrition p55).