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Beatrix Kenesei

Protein Supplement Guide for Athletes

Most athletes striving to optimize their nutrition add protein supplements to their diet for reasons of:

  • convenience (and easy preparation),
  • lower cost (relative to meat and fish products),
  • avoid the concurrent consumption of carbohydrates and fats (to minimize adding calories while meeting protein needs),
  • to avoid meat consumption. (See our previous article about nutrition.)

Due to technological and regulatory reasons (see later) the protein supplement market has boomed since the ‘70s resulting in an overwhelming diversity of products. The most popular protein supplements are today:

  • milk based proteins: whey and casein
  • egg white/albumin
  • collagen
  • legume proteins: soy, pea
  • grain proteins: rice, hemp
  • seed proteins: sunflower, pumpkin seed
  • insect proteins
  • Spirulina
  • Mycoprotein
  • and various combinations of the above

So how to choose the right protein product from the myriad of options? Before you pick one, ask yourself the following questions:

  1. Is it a complete protein source?
  2. Is it easily digestible/bioavailable?
  3. What else besides protein is in that product?
  4. Do you have any allergies/ food sensitivities to any substance in that product?

1. Complete protein sources.

A complete protein or whole protein is a food source of protein that contains an adequate proportion of each of the (in humans nine) essential amino acids (EAA). Essential amino acids can not be synthesized de novo by the organism and must be supplied in its diet. Of the 21 amino acids common to all life forms, the nine amino acids humans cannot synthesize are phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and histidine.

Six other amino acids are considered conditionally essential in the human diet, meaning their synthesis can be limited under special pathophysiological conditions or individuals in severe catabolic distress. Six amino acids are non-essential (dispensable) in humans, meaning they can be synthesized in sufficient quantities in the body.

EssentialConditionally essentialNon-essential
Histidine (H)Arginine (R)Alanine (A)
Isoleucine (I)Cysteine (C)Aspartic acid (D)
Leucine (L)Glutamine (Q)Asparagine (N)
Lysine (K)Glycine (G)Glutamic acid (E)
Methionine (M)Proline (P)Serine (S)
Phenylalanine (F)Tyrosine (Y)Selenocysteine (U)
Threonine (T)
Tryptophan (W)
Valine (V)

It is not only important to consume all 9 essential amino acids, but equally important to consume them in the right proportions! In other words for high net protein utilization (the mass ratio of amino acids converted to proteins in our body to amino acids supplied) we need to consume a good balance of the essential amino acids. The current RDA’s (Recommended Dietary Allowance) for essential amino acids are as follows:

Amino acid(s) WHO mg per kg body weight WHO mg per 70 kg US mg per kg body weight
Methionine + Cysteine10.4 + 4.1 (15 total)1050 total19 total
Phenylalanine + Tyrosine25 (total)1750 total33 total

Note, that some amino acids can not be synthesized de novo but can be converted into each others by our body such as methionine can be converted into cystein and phenylalanin into tyrosine (thus making cystein and tyrosine non essentials.)

When we consume protein sources lacking the essential amino acids, our body turns them into carbohydrates (via gluconeogenesis) or fat and eventually they will be used as energy sources for the body.

Complete proteins are meat, poultry, eggs, fish, insects (like crickets), milk, and cheese containing a balanced set of EAAs. There are many near complete vegan protein sources such as soy, pea, rice, hemp etc. They technically contain all EAAs but not in the right balance. They have 1 or 2 limiting amino acid (the essential amino acid found in the smallest quantity in the food). In legume proteins (soy, pea) it is tryptophan, in grain proteins (rice, hemp, wheat etc.) and seed proteins (sunflower) it is lysine, in beans it is methionine.

This drawback of plant proteins, compared to animal proteins, can be counterbalanced by mixing different vegan protein sources together, or by adding an EAA mix on top of them, thereby reaching a more optimal EAA profile.

2. Protein quality: digestibility and bioavailability

You can read in detail about this topic here:


Numerous methods exist to determine protein quality by assessing digestibility and bioavailability of the amino acids, like BV, net protein utilization and PER and by also assessing its essential amino acid composition like PDCAAS.

Biological value (BV) measures protein quality by calculating the nitrogen used for tissue formation divided by the nitrogen absorbed from food.

Net protein utilization is based on nitrogen ingested instead of absorbed.

Protein efficiency ratio (PER) is based on the weight gain of a test subject, (rats), divided by its intake of a particular food protein during the test period.

Protein digestibility-corrected amino acid score (PDCAAS) is a method of evaluating the quality of a protein based on both the amino acid requirements of humans and their ability to digest it.(mg oflimiting amino acid in 1 g of test protein / mg of same amino acid in 1 g of reference protein) x fecal true digestibility percentage.) Note that this definition means that any non complete protein has a 0 as it’s PDCAAS value.

PDCAAS is currently the most accepted and widely used method, although it has some limitations, too, such as overestimation in the elderly (likely related to reference values based on young individuals), not counting amino acids utilized by the gut microbiom, and antinutritional factors.

Antinutritional factors such as trypsin inhibitors, lectins, and tannins present in certain protein sources (such as soybean meal, peas and fava beans) may cause reduced protein hydrolysis and amino acid absorption. This may also be more effected by age. (See: The protein digestibility-corrected amino acid score, Schaafsma G J Nutr. 2000 Jul;130(7):1865S-7S.)

Protein Type Protein Efficiency Ratio Biological Value Net Protein Utilization Protein Digestibility Corrected Amino Acid Score
Black beans000.75
Soy protein2.274611.00
Wheat gluten0.864670.25
Whey protein3.2104921.00

(Adapted from: U.S Dairy Export Council, Reference Manual for U.S. Whey Products 2nd Edition, 1999 and Sarwar, 1997.)

Insects have very high protein quality indexes, too. Such as crickets (Gryllus assimilis) with BV=93, PDCAAS=0.73. Read more here.

3. What else besides protein is in that product?

Many protein products contain added sugars and trans fats for flavoring, try to avoid those by all means.

But unfortunately that’s not all what your product may contain due to regulatory problems.

In 1994, the Dietary Supplement Health and Education Act (DSHEA) was signed into law in the USA. Under DSHEA, responsibility for determining the safety of the dietary supplements changed from government to the manufacturer and supplements no longer required approval from the U.S. Food and Drug Administration (FDA) before distributing a product (!). Since that time manufacturers did not have to provide the FDA with the evidence to substantiate safety or effectiveness unless a new dietary ingredient was added. It resulted in booming product sales with more and more new products and with much less product safety unfortunately. As a result there is basically no guarantee what your product contains leading to spiked products and potentially contaminated products on the market. Which means when you are choosing any supplement your biggest concern should be to find a high quality provider which puts their products through a safe and reliable way of testing.

Also, many protein products contain a lot of additional essential nutrients on top of proteins, adding more benefits to the product, such as insect protein, Spirulina, Mycoprotein. More details below!

4. Do you have any allergies/ food sensitivities to any substance in that product?

Dairy based proteins provide the most common allergies and food intolerances, followed by egg proteins. Mycoprotein (derived from fungi) allergies are not well known like the previous ones, but can be severe. And persons with shellfish allergies may exhibit an allergic reaction to insect protein products.

Now that we know what to look for in a protein supplement product let’s walk through the most popular protein sources!

  1. Milk proteins. The protein in cow’s milk is 20% whey and 80% casein. (For comparison human milk contains 60% whey and 40% casein.) Whey protein is a mixture of proteins isolated from whey, the liquid material created as a by-product of cheese production (the left over liquid from milk coagulation). All whey products have a very fast absorption rate. Whey protein concentrates have typically a low (but still significant) level of fat and cholesterol, but they are higher in carbohydrates in the form of lactose. (Avoid these products if you have lactose intolerance.) Whey protein isolates are processed to remove the fat and lactose. Whey protein hydrolysates are predigested and partially hydrolyzed whey for easier metabolism and reducing the allergenic nature of milk proteins. Casein is the major component of cheese. It is digested and absorbed much more slowly than whey. Most milk protein allergies are casein allergies.
  2. Egg proteins (=egg white/albumin). A complete protein source with high digestibility and a moderate digestion speed (in between whey and casein), eggs have a high protein content relative to other sources.
  3. Collagen. Collagen has a special place on this list since it is the main structural protein in the extracellular matrix in the various connective tissues in the body. It is the most abundant protein in mammals (!), making up from 25% to 35% of the whole-body protein content. Depending upon the degree of mineralization, collagen tissues may be rigid (bone), compliant (tendon), or have a gradient from rigid to compliant (cartilage). It is not a complete protein and has an unusual amino acid profile with a very high content of proline (hydroxyproline) and glycine. It is the best protein source to boost your body’s collagen production and help it repair it’s connective tissues (which get to break down during exercise, too!). Regular consumption reduces injury and accelerates returning to training. (Read more here.) It may also relieve joint pain, could prevent bone loss, and may improve skin health.
  4. Legume proteins. Such as soy, pea, black bean, vary in their amino acid profiles. Pea and black bean are not complete (limiting essential amino acids: Meth +Cyst) while soy protein is complete. Pea and black bean proteins also have a much lower digestibility value than soy. Soy protein is available as an isolate (a highly refined or purified form of soy protein with a minimum protein content of 90% ) or as a concentrate (about 70% soy protein). Soy concentrates retain most of the fiber content of the soy beans (with the soluble carbohydrates being removed). Some are concerned about soy’s phytoestrogen content.
  5. Grain proteins, such as rice, hemp, wheat, oat. Not complete (Lys) protein sources, low digestibility.
  6. Seed proteins. Sunflower seed, pumpkin seed. Similar to grain proteins with Lys as limiting EAA. The latter 3 categories (vegan proteins) are the best combined together to achieve a more optimal EAA ratio.
  7. Quinoa. Quite an outlier, not a grain, complete protein. It could be a very high quality protein supplement but the procedure of making quinoa protein concentrate is still under development currently by several companies. We might see it hitting the market in the future, until then enjoy the whole grains with it’s many benefits (but high carb content)!
  8. Insect proteins. In mass production it is sourced from crickets, locusts or mealworms. Complete protein source, includes unsaturated fat, prebiotic fiber (derived mostly from the chitin that makes up their exoskeleton), vitamins and essential minerals making it nutrient rich. It is also a much more sustainable protein source compared to other animal proteins, because insects have an incredible ability to convert their food into edible body mass with needing much less land, water and feed.
  9. Spirulina is a cyanobacteria (photosynthesizing bacteria). It has high protein content, and is a complete protein source. Rich in vitamins, minerals, unsaturated fatty acids. Highly sustainable, potential food source for providing food security. It is being studied as a potential nutritional supplement, too.
  10. Mycoprotein is protein derived from fungi for human consumption, it has been developed only the last few years. We might see much more of these products coming in the future (and more studies). Not a complete protein source (limiting: Meth +Cyst), mostly sold as a mixture with vegan proteins to counterbalance that. It is rich in prebiotic fiber and very low in fat. Also rich in vitamins and minerals. Potentially a nutritional supplement, too, more studies needed.

Putting this all in a nutshell, go for high quality products with no fillers, sugars and saturated fats. Choose companies which use an independent system to monitor the quality of their products. If you choose vegan proteins, choose mixed proteins with a better EAA profile or add extra EAA supplements to your diet! Also consider adding collagen products to your diet for their amazing connective tissue building capacity.

Today’s protein market tends to grow toward insects, Spirulina and Mycoproteins. They contain many additional nutrients (prebiotic fibers, vitamins, minerals, bioactive compounds) compared to the traditional animal ones while providing high quality proteins with less digestive issues.

At Revolution Fitness we decided to sell only the best products available on the market from companies we highly trust. We mostly focus on collagen, crickets, Spirulina and Mycoprotein products, but we offer some high quality traditional proteins, too.

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