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Protein is an essential nutrient in the diet. It is used by the human body to produce protein for structure (building muscles) and function (boosting immune system and regulating/producing hormones). Regulatory proteins act as enzymes or transport vehicles. Proteins are composed of various sequences of roughly 20 different amino acids., nine of these amino acids are essential. Essential amino acids must be consumed in the diet, while the body can synthesize the non-essential amino acids. Proteins is the third fuel source during exercise. It provides 3-5% of energy expenditure during exercise.

What foods contain protein?
Protein can be found in wide variety of animal and plant foods.

Animal Sources
* Meat products: beef, pork or chicken
* Eggs
* Dairy products: cheese, milk, yoghurt
* Seafood: fish and shellfish
* Yoghurt

Plant sources
* Legumes: kidney beans, chickpeas
* Grains and cereals: wholemeal bread, pasta and rice
* Soy products: tofu, soy milk
* Nuts/seeds
* Sports products: whey protein, recovery drinks

Note: most food contains protein.

How much protein do I need?
Muscle protein is constantly being built and broken down. Not all of this broken down protein is recycled within the body. Some of it is also excreted, creating a daily need to top up protein supplies through diet. The recommended dietary intake (RDI) for protein in the general population is 0.8 g/kg daily. However, both strength and endurance athletes may have greater protein needs. The table below summarizes the protein requirements in athletes.

Group Protein intake (g/kg/day)
Sedentary men and women (0.8)
Endurance athletes (1.6)
Strength & Power Sports (1.6-7)
Technical Sports (1)
Tennis (1.4-1.6)

Do athletes need to eat a protein rich diet?
When an athlete has a higher requirement for protein than a sedentary individual, does this mean that they need to change their diet to include more protein serves? In particular, do they need to focus only on very high protein foods, or take protein supplements?

On average in a non restricted diet (i.e. non vegetarian, dairy eating individuals) about 12-15% of energy intake is in the form of protein. Athletes typically have a higher food intake which ensures that these increased requirements for protein are met.

Numerous dietary surveys show that the dietary patterns of athletes provide protein intakes that are well in excess of 1.2-2.0 g/kg body mass per day. Therefore, there is no justification for special high protein eating strategies for sport.

A typical American consumes 1.6g protein/kg. It is very easy for athletes to obtain their increased protein requirements by diet.

Can people have too little protein?
Although most people including athletes eat more protein than is required to meet their special needs for sport, there are some athletes whose diets may be inadequate in protein.

These athletes include:
* People on low energy diets trying to achieve or maintain a lower body mass/body fat level.
* People restricting dietary variety, especially those cutting out large numbers of food groups. This includes fussy eaters, vegetarians with poor diets, people with extensive allergies or food intolerances .i.e. lactose intolerance,
* People travelling to places with a restricted food supply
* People following extreme carbohydrate-rich diets
* People with eating disorders or disordered eating problems, and those following fad diets (e.g. the Cabbage soup diet, or long-term juice and vegetable fasts) are also at risk of sub-optimal protein intake among other nutrient inadequacies

Failure to consume sufficient protein on a regular basis may cause muscle to be broken down for use by the body. This will lead to loss of strength and power, increased likelihood of injury or a failure to make optimal gains from training.

Which are the best foods to provide protein?
The following table indicates the protein content of many basic low fat foods. People often turn to meat, poultry and dairy products to obtain protein. Don't forget that plant foods can also contribute significant amounts of protein to the overall diet.

Dietary sources of protein - animal and plant (each serve contains 10g protein).

Animal
33g beef, pork, lamb or chicken (cooked)
50g fish (including canned e.g. tuna)
2 small eggs
30g reduced fat hard cheese
70g cottage cheese
1 cup low fat milk
Tub of yoghurt (200 g)
150ml liquid meal supplement

Plant
4 slices wholemeal bread
3 cups breakfast cereal (90 g)
1/2 can (220 g) baked (or kidney) beans
2 cups cooked pasta
3 cups cooked rice
120g tofu
60g nuts or seeds
300ml soy milk

Table sourced from Sports Dieticians Australia

Thanks to:
Susie Parker-Simmons
Sports Dietitian (RD) & Physiologist
Nutrition Advisor,
Sony Ericsson WTA Tour
for providing the dietary information for this piece

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Sports Drinks

Calcium