Beefing up

Taking protein supplements to build muscle mass is popular with gym-goers but the best way to get those essential amino acids is still from food.

Question: My son and a number of teenagers I encounter take protein supplements after exercising to help build muscle mass. Is there any scientific evidence to support this, and are there any risks with high-protein diets?

Iapplaud your scepticism, as many dietary supplements are indeed unnecessary – or, at best, taken by people who already have a balanced diet and do not need the additional nutrients.

The use of protein supplements for building muscle mass is, however, backed by some sound scientific support, although it is recommended that athletes first attempt to meet their protein needs with food. Protein is both a handy energy source and an important building block for our body. The human body is about 15-20% protein by body mass. So the body of a 70kg adult, for example, contains about 11kg of protein or more.

About half of the protein in a human body is present as skeletal muscle. In addition to forming our muscle fibres, proteins, which are complex molecules built from various amino acids, have many other important roles, such as in enzymes, antibodies, blood-transport molecules and more.

Protein is found in all living cells, including both animal and plant foods. Of course, some foods are richer sources of protein, such as meat, fish and poultry, along with legumes, eggs, nuts and seeds, while smaller levels are found in milk, cheese, yogurt, other dairy products, whole grains, vegetables, and fruit.

The proteins in our bodies are made from about 20 different amino acids, most of which we can

It should be noted that excessive protein intake can cause health problems.

synthesise. However, eight amino acids, called essential amino acids, must be provided by our diet, as our bodies are unable to synthesise them. Interestingly, in nature, milk and eggs have an amino acid composition most similar to our bodies.

The recommended daily intake of protein for a sedentary male is 0.84g per kilogram of body mass, which equates to about 64g; for women, it is 0.76g/ kg, or around 46g a day.

But when an individual performs regular exercise, their daily requirements for protein increase to support the maintenance and growth of muscle, which is part of the body adapting to the training. Athletes in heavy training, for example, require 1.2-1.6g/ kg daily, according to the Australian Institute of Sport (AIS), which is up to double the amount recommended for sedentary populations.

It should be noted, however, that excessive protein intake can cause health problems. Indeed, long-term consumption of a highprotein diet has been linked to loss of bone mass and kidney dysfunction, among other things.

Ideally, the daily targets for protein are spread over the day and are best served by including a small serving of proteinrich foods at three to five eating times. For example, the AIS suggests including protein in three main meals, a post-training snack and a before-bed or mid-afternoon snack.

There is evidence that protein consumed before or after a workout optimises performance and the body’s recovery.

Although the greatest impact on muscle synthesis is the amount of protein eaten over a 24-hour period, there is evidence that protein consumed before or after a workout (particularly after) optimises performance and the body’s recovery after training.

The same is true whether the exercise was resistance training (such as weightlifting) or endurance training (such as running). So, the young men you mention are following current advice that suggests taking protein supplements after their weight-training sessions may boost their ability to build skeletal muscle.

Ideally, athletes would get their required protein needs met by foods, rather than supplements, as foods will provide a range of other useful nutrients and energy.

For an adult, baked beans on two pieces of wholegrain toast and a pottle of yogurt provide about half of our regular daily protein needs; a beef or lamb steak and a glass of milk provide 80%.

Animal-derived proteins are considered to have higher biological value, as they are closer in profile to that of human proteins.

Whichever source a person chooses, athletes should aim to meet most of their protein needs through a variety of foods, and use isolated protein supplements only as a top-up to meet those higher needs to support training. ▮