Читать книгу Eating for Sport - Shelly Meltzer - Страница 18

Current accepted recommendations on protein requirements for athletes fall in the range of 1–2.2g/kg body weight or as a percentage of total energy intake (15–20%). Protein requirements in exceptional situations such as pregnancy, high altitude and low-energy eating will be discussed later. The emphasis should always be on good quality protein of high biological value such as lean red meat, chicken, fish, eggs and low-fat dairy, which are rich in all the essential amino acids and are also the primary sources of certain micronutrients such as calcium, vitamin B₁₂ and bio-available iron and zinc. A low intake of protein and poor quality protein can lead to deficiencies of these micronutrients.

Vegetable sources of protein are considered to be of low biological value since they do not provide the full range of the essential amino acids. Therefore, even if you have sufficient protein (amount in grams) but one of the essential amino acids is lacking (the limiting amino acid) you will not be able to utilize the other amino acids to synthesize protein! This should not be interpreted as an excuse to supplement with single amino acids. Safety and efficacy data is still lacking for single amino acid supplementation and so no upper safety limits have been set.

Vegetarians who eat plant foods only, in the absence of complementary mixtures of plant protein may have an inadequate intake of essential amino acids (see pp 81, 82).

Practical tips

1. Choose a variety of protein-rich foods.

2. Protein should also be distributed throughout the day. Do not let protein dominate all meals, so that you leave enough space on your plate for all the carbohydrate needed.

3. Always choose lean meat and low-fat dairy products as many of these protein-rich foods contain hidden sources of fat.

4. If you are a vegetarian you need to make a special effort to ensure that your diet provides enough good quality protein. By mixing different vegetable proteins such as baked beans on toast, lentils and rice, or a peanut butter sandwich you will achieve good protein combinations (see p82).

5. Many proteins are expensive so it is important to explore ways of extending or stretching the protein without reducing the nutritional value. Dried beans and lentils can be added to stews and soups. Other good economical sources of protein include pilchards, sardines, eggs and skim milk powder (which can be added to many drinks, cereals and soups).

6. Commercially available, specially formulated liquid meal replacements that provide carbohydrate and protein can also be used.

7. To increase your muscle mass you need to follow your eating plan and training programme. If you only concentrate on a high protein intake without enough carbohydrate, then the protein will be used for energy instead of being used to build muscle! Moreover, too little carbohydrate will lead to low energy levels, which will make it very difficult for you to train and perform at your best.