Nutrients from foods that we need in large amounts are called macronutrients such as protein, fats and carbohydrates. In contrast, micronutrients such as minerals and vitamins are only needed in relatively small or micro amounts. Proteins are made up of chains of amino acids, the building blocks of protein and when we eat or drink foods containing protein, the protein is broken down into amino acids. The body can then utilize these amino acids to build all the different proteins it needs.
Why do we need proteins?
We all need protein in our diet but athletes, especially growing ones need even more. Every single cell in the body is made of protein such as enzymes, skin and bone, antibodies for immunity, muscle growth and repair. To grow and stay healthy we need adequate protein. Proteins are also brain food. Amino acids create neurotransmitters such as dopamine and norepinephrine (focus and concentration) endorphin (pain) and serotonin (mood and sleep) so are critical for high performance. Most of our energy comes from carbohydrates and fats, however protein also contributes to our energy tank. Proteins are continually broken down and remade throughout the day allowing new proteins to be formed. We are not good at storing protein, so we need adequate daily sources.
Where do we get protein from in our diet?
There are many amino acids but 9 of them cannot be created in the body and are therefore considered to be “essential amino acids” (EAAs) and must be obtained through our daily intake of food and drink.
Not all proteins are created equal. Foods which are rich in high levels of EAAs are considered as complete or high-quality proteins if they contain all the essential amino acids in the correct quantities and ratios to increase muscle protein synthesis (Kerksick, 2019). These include many animal sources such as meat, dairy, fish and eggs. Milk and egg white are some of the most complete proteins available and have been shown to have similar effects to supplements containing whey protein and casein on muscle protein synthesis which is the process by which we build muscles when coupled with resistance training.
“Incomplete proteins” are lacking at least one essential amino acid or the essential amino acid content doesn’t have the right proportions or quantity (Kerksick, 2019). Many vegetarian based proteins such as beans, seeds, nuts and grains are lacking in all the EAAs to are regarded as incomplete, however, by combining different incomplete proteins in the diet it is possible to achieve all the building blocks we need from plant-based sources. Plant based protein sources tend to be quite filling, so care should be made in younger athletes that they do not fill up just on protein dense food and miss out on other macronutrients such as carbs and fats.
How much do we need?
The continual turnover of proteins means athletes should consume protein regularly throughout the day, to allow adaptations to exercise training to occur. In sedentary adults, figures for recommended daily allowance (RDA) from World Health Organisation are 0.83 g/kg/d of body weight. To start to calculate your individual needs, therefore, start my weighing yourself in kgs. The International Society of Sports Nutrition recommends consuming between 1.4g-2g per kilogram of body weight per day to build and maintain muscle mass in athletes, depending on the demands of the exercise regime. There is no solid evidence about these figures for adolescents and how they may differ according to maturation.
Example of an adult athlete:
For a 70kg athlete requiring 1.4g/kg that equals 98g per day in total. This should be spread evenly over 4-5 meals a day not just after sport so approximately 20g of high-quality protein per meal depending on your body weight (0.25 g of protein per kg body mass per meal).
Excessive amounts of protein will be broken down and peed out so consuming more than you can use is not an effective strategy. To increase both muscle mass and strength you need to combine resistance-type exercise with an adequate dietary protein intake as muscle growth comes from regular training and a balanced diet, not through supplements or protein shakes. Where possible we should source our protein intake naturally through whole food sources not through supplements. If you decide to add protein powders to your diet, check the contents list for other additives that may be banned in your sport and are not always appropriate for growing athletes. Check out https://www.wada-ama.org/en/content/what-is-prohibited
What does this look like?
To compare one food against another, converting it to it’s value per 100g is more reliable to avoid changes in portion size for example. This does not mean you should eat 100g! These are approximate values for foods traditionally high in protein and vary from source to source.
What happens when we don’t get enough protein?
If we accept that protein forms the building blocks of so many tissues and essential processes in the body, then a lack of protein in the diet is likely to have serious consequences on the overall health of the body. In particular, research points to low levels of protein intake being related to loss in muscle but it is not just muscles that suffer. Research points to the link between protein and overtraining syndrome which is characterised by a loss of performance and illness. If you are injured, then your body needs protein to create the tissues needs for healing so make sure you are getting adequate high-quality protein in your diet.
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