Nutrition for Athletes: The Essential Guide to Protein

Everything you need to know about protein.


The word protein originates from the Greek ‘protos’, which means ‘the first’. Proteins are the basic building blocks of the human organism. All tissues and organs contain proteins. Apart from that, proteins also fulfill signalling functions in the neural system.

The Amino acid tryptophan, included in the proteins from chicken or turkey meat, is important for production of serotonin, which is an important neurotransmitter, and melatonin, which regulates the sleep cycle.

Albumin is a reserve protein, which regulates distribution of nutrients and maintains the pressure in the blood capillaries. Low albumin levels can signal liver disease or problems with processing the nutrients. A high level of albumin is typical during dehydration.

Transferrin is a transport protein for iron. It is related to immunity-boosting lactoferrin, which can be found in whey protein supplements with lower degree of processing (concentrate).


The human body is composed of approximately three trillion molecules of proteins. They are composed of amino acids. Individual amino acids form longer chains – peptides. Out of twenty amino acids that can be found in the human body nine are essential.

The body cannot produce them from other amino acids and we must take them directly from food. (phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, histidine) BCAAs – branched chain amino acids, which are often used by athletes, also belong to this category.


Amino acids in human tissue are bound together in different combinations. This combination is unique for each organ and it is encoded in the DNA sequence. Because of this our appearance and physical abilities depend on the genes. Certain health defects and diseases can also be caused by the absence of a gene that encodes particular proteins.

Individual amino acids fall into the mechanism of building muscles, neural signalling and they can be used as a source of energy.  However, they are easily obtained from various animal tissues and they depend on synergic effect. Therefore they do not replace full protein.


The recommended daily intake for the maintenance of good health is 0.8 g of protein a day, which represents 64 g of protein for a 80 kg man. It can be found in chicken breast fillet (150 g) with rice, glass of milk and a cup of cottage cheese.

A 60 kg woman needs 48 g of protein, which she gets from 100 g serving of salmon, one baked potato and a chocolate milkshake. Adequate protein intake is crucial for children that are still in development. The same applies to adults with physically or mentally demanding jobs (such as professional athletes).


Strength athletes need more protein to regenerate muscle tissue broken down during training. Studies proved that higher protein intake has positive impact on the development of strength and muscle mass. Recommended amount is 2-2.5 grams per kg of bodyweight. Amino acids facilitate the repair of muscle tissue and improve recovery, especially glutamine.

Endurance athletes also need to repair muscle tissue. Several studies proved positive effects between higher protein intake and recovery rates. Protein drinks combined with BCAAs and quick absorbing carbohydrates can come in handy to fulfill these aims.


It is not recommended to take 3 or more grams of protein per kg bodyweight. You risk problems with digestion and it can also result in kidney and liver issues.

Too much protein causes acidosis of the organism, which can even be enhanced by intensive workouts. It lowers the Ph, which negatively affects sport performance. An acidic environment in the muscles causes fatigue and accumulation of waste. Supplements such as beta-alanine or carnosine help with clearing the waste.


Diet rich in protein has better satiating effect than for example carbohydrate dominant diet. It keeps insulin level low and we do not have cravings that usually occur after consumption of sugary snacks. Moreover, the processing of proteins is more energy demanding than processing of carbohydrates, which increases the overall energy expenditure.


The main source of protein should be food. Protein supplements are just an addition. Protein supplements are concentrated sources of nutrients, in this case proteins. They can also include additional substances, such as individual amino acids, vitamins or creatine.

They must meet the food legislation criteria of the particular country but they do not have to be approved by medical authorities. They should not be considered medications and they cannot include health claims on the label. The legislation can vary depending on the particular country. Some companies have separate manufacturing lines for the US and European market.


Whey protein is associated with highest degree of utilisation by human organism. It contains the whole amino acid spectrum and in case of whey concentrates (WPC) and some isolates (WPI), it contains additional substances that support health and immunity. However, these are filtered out during more precise processing, for example hydrolysis.


  • Aim for the highest possible amount of protein in a single serving and low sugar and fat.
  • Make sure that it contains all 20 amino acids needed for the human body and at least 5-6 grams of BCAAs (branched chain amino-acids) in one serving. Athletes usually put additional BCAA to their protein drink, especially pre or post workout.
  • Prefer products that have a full list of ingredients, including amounts.
  • Be suspicious of individual amino acids (taurine, glycine, glutamine) listed separately on the label. The manufacturers use them in order to replace pure protein but keep the overall nitrogen profile. It is cheaper. (so called amino spiking)
  • Products sweetened by sucralose usually taste well and do not leave bitter after taste.
  • Avoid complex products that contain multiple substances (protein, creatine, carbohydrates). The quality can be questionable. Instead buy each component individually and mix them at home.



If you want to increase the amount of protein in your diet, without any specific performance goals, go for a whey concentrate. You can mix it with water post-workout or add to your favourite cereals and yoghurt.

  • Contains 35-80 grams of protein per 100 g.
  • Higher content of fats and carbohydrates.
  • Contains lactose.
  • Bio-active substances, such as immunoglobulin and lactoferrine, boost immunity.


Suitable for those, who want to improve their performance. Take post-workout, mixed with water for faster absorbtion.

  • Contains at least 90 grams of protein per 100 g.
  • Undergoes further filtration which minimizes the content of carbohydrates and fat but also filters out some of the bio-active substances (depending on the level of processing(.
  • Faster absorption than WPC.
  • Higher price than WPC but contains higher quality protein.


  • Contains 90 g or more protein per 100 g.
  • Proteins are pre-digested to peptides, which can be built directly into the muscles.
  • Quick absorption and instant supply of amino acids makes it ideal post-workout protein.
  • Used by professional athletes.
  • Mix with water (milk slows down absorption).
  • Higher price and the taste is not always pleasant.
  • With whey hydrolyate, make sure that it contains at least 90 percent of protein. If not, it is most probably concentrate or isolate with addition of hydrolysate.


About 80 percent of protein in milk is caseine. Unlike whey, which represents 20 percent, caseine is not water soluble therefore its absorption in the body takes longer, up to 7 hours. It makes it an ideal night protein, supplying amino acids while we sleep. Two most common forms are micelar caseine and calcium caseinate.

Calcium caseinate is better soluble and contains more minerals. The BCAA content is lower and dues to higher degree of processing, it preserves less of the original characteristics.


Is suitable for vegans, vegetarians or people suffering from lactose intolerance. It is quickly absorbing and contains the whole amino acid spectrum. The amount of individual amino acids is different than in whey. For example, soy is good source of arginine, which improves blood flow and supply of nutrients to the muscles.


Beef protein is obtained from the tissues of livestock. It contains all amino acids and it is popular with people who follow paleo diet.


Egg protein was popular before the arrival of whey. It contains egg albumin, which is important for the regulation of capillary pressure.


Complex proteins combine the advantages of fast and slow absorbing proteins. They can be taken after workout or before bed, therefore they are suitable for the people who do not want to spend money on two different proteins. It is ideal if they contain four and more components, including whey concentrate or isolate and caseine.


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