Learning how protein works can help you get more out of your supplement regimen. These common myths might be holding you back. Get the scoop so you can get your gains.
Myth 1: High protein intakes will not affect muscle protein synthesis
Fact: Greater availability of amino acids means more protein synthesis within muscle cells.
Experiments have shown that lab animals can survive on very limited protein as long as they have enough fat and carbs. Simply put, the body begins to lower amino acid oxidation to spare nitrogen containing compounds.
Yet can we really apply this kind of example to adult humans trying to build muscle? I think not.
When the body begins getting stingy with amino acids because of low protein intake, nonessential functions, such as skeletal muscle protein synthesis, drop to minimal levels.
Other functions within the body such as the immune system, which uses glutamine primarily of muscle origin for fuel, also begins to suffer.1
This cripples the body's ability to cope with the stress and tissue damage from intense training. Some researchers even believe that the currently recommended protein intakes may actually lead to illness because they don't include enough amino acids.2
Research clearly shows that by increasing blood levels of amino acids you increase protein synthesis in skeletal muscle.3,4 It has also been shown that you can keep a positive nitrogen balance for long periods of time and that nitrogen accretion will tend to continue as long as protein intake is high.5
Clearly, if you want to maximize your gains in the gym you've gotta get more protein than the average Joe.
Myth 2: You can only assimilate 30 grams of protein at one sitting
Fact: The body has the ability to digest and assimilate much more than 30 grams of protein from a single meal.
Speaking of high intakes of protein, people have been perpetuating the myth that you can only assimilate about 30 grams of protein at a time, making protein meals any greater than a 6-ounce chicken breast a waste.
This is anything but true. For example, the digestibility of meat is about 97 percent efficient. If you eat 25 grams of beef, you will absorb into the blood stream 97 percent of the protein in that piece of meat. If you eat a 10-ounce steak containing about 60 grams of protein, you will again digest and absorb 97 percent of the protein.
If you could only assimilate 30 grams of protein at a time, why would researchers be using in excess of 40 grams of protein to stimulate muscle growth?6
Critics of high protein intakes may try to point out that eating more protein only leads to burning more protein. This is true, nevertheless, some researchers speculate that this increase in protein oxidation following high protein intakes may initiate something they call the "anabolic drive".7
The anabolic drive is marked by hyperaminoacidemia, an increase in both protein synthesis and breakdown with an overall positive nitrogen balance.
In animals, anabolic hormones like IGF-1 and GH also go up.8 Though it's hard to track that in humans, lean tissue accretion does go up with super high protein intakes.9,10
The take-home message is that for more muscle growth you need less muscle loss, and more protein synthesis. You get this with heavy training, enough calories, and high protein consumption.
This means that meals with more than 30 grams of protein will be the norm. And all that protein will be put to use by the body.
Myth 3: Protein must be rapidly digested to build muscle
Fact: Both rapidly and slowly digested proteins offer significant benefits to athletes.
Some proteins are "fast" and others are "slow".11 This is based on how fast they raise blood levels of amino acids after you eat them. Whey protein is a fast protein and causes amino acid levels to go up quickly. Casein on the other hand is a slow protein.
Both fast and slow proteins are good for someone trying to build muscle. Proteins that enter the blood stream quickly increase protein synthesis significantly. Proteins that enter the blood stream slowly are beneficial for keeping protein from breaking down, even if you don't eat that much of them.
By using both fast and slow proteins, you should be able not only to jump-start protein uptake into muscle cells during a grueling workout, but also make sure that protein synthesis is jump-started and that protein breakdown is kept very low during the hours after the workout. Take the fast protein before training, and a slow protein after for the best muscle-building effect.
In summary, it is a mistake to say that a "fast" protein is better than a "slow" protein. Both types of protein should be used strategically to tweak protein metabolism in favor of muscle growth.
Myth 4: A protein must have added peptides of specific molecular weights to effectively build muscle
Fact: The body's digestive tract makes its own variable molecular weight peptides from the whole proteins you eat.
As soon as protein hits the stomach it is attacked by powerful stomach acids. This acid, along with an enzyme called pepsin, serves to change or denature the protein's structure, preparing it for further digestion in the small intestine.
In the small intestine several other enzymes work to break down the protein into various molecular weight peptides and free amino acids. Each enzyme acts on a specific part of the amino acid chain, breaking it in the appropriate place.
Whether you've just eaten a steak, scrambled eggs, or a glass of whey protein, the end result of digestion is the same, a full spectrum of molecular weight peptides and a moderate amount of free amino acids perfectly suited for absorption into the body.
The small intestine has special transporters which actively pull peptides across the brush border membrane and into intestinal cells. As a result of these transporters, peptides can be actively absorbed faster than free amino acids.
Within intestinal cells, peptides are further broken down into individual amino acids by enzymes called protease.
It has been shown that a very small percentage of digested peptides can enter the bloodstream by squeezing between intestinal cells. Even though some peptides make it into the bloodstream intact, they are quickly broken down by proteases on the surface of liver and muscle cells. If by some small chance peptides actually make it all the way into these cells, they are rapidly broken down by proteases within the cell.
So all this talk about adding various molecular weight peptides just means that the manufacturing process predigested an already easily digestible protein. This simply adds to the expense of making the protein. The added cost, of course, is passed on to you.
Myth 5: Drinking raw eggs is a great way to get extra protein.
Fact: Raw eggs can be dangerous, leach nutrients, and give you really gnarly gas.
Salmonella poisoning is something many of you are probably familiar with. This is one reason why drinking raw eggs is not a good idea.
Many people wonder if they can they drink pasteurized egg whites since this would kill the salmonella. The answer is yes, but what you have to watch out for here is that eating raw eggs can leach biotin out of your body. Biotin is a vitamin that plays an important role in the body and drinking raw eggs can lead to a deficiency.12
Drinking your eggs raw instead of cooking them can also prevent the body from fully absorbing all the protein from the egg. Only about half of the protein gets absorbed.
The last thing you have to watch out for is the foul stench that will follow you around like you have a New York sewer in your back pocket. Raw eggs will give you farts like you wouldn't believe!
Myth 6: Arguments over which protein scores highest on various methods of protein assessment will make or break your success in the gym.
Fact: As protein intake increases the influence of protein quality decreases. In other words, high quantity can significantly make up for low quality.
The amount of protein in the foods you eat makes each protein's quality scores less important. If you only eat 35-45 grams of protein a day, you'd better make sure you choose the highest quality protein you can find.
On the other hand, if you eat the quantities of protein common among bodybuilders, say 1.6-1.8 grams per kilogram of body weight, the large amount of amino acids overcome slight differences in scoring.
Once you get to a certain level of quality in a protein supplement, increasing it further will not really make it work better when you're eating enough to pack on muscle.
Methods Of Testing Proteins
Here is a quick overview of the methods used to determine protein quality. Keep in mind that tests used to determine protein quality use the lower threshold of protein requirements. This creates a metabolic environment far different from that seen in a well-fed bodybuilder or athlete.
The most obvious way to judge the quality of a given protein is to break it down into its individual amino acids. This amino-acid profile is then compared to a standard profile. Egg protein is the standard that is used in a chemical scoring scale for protein quality and has a rating of 100.
Take, for example, a protein that has a limited amount of a specific amino acid. This amount is then compared to the amount found in egg protein. If the amount in the test protein is 75 percent of that found in egg protein, then the test protein gets a rating of 75.
From this you would assume that if you could feed a person an amount of this protein that is exactly their requirement, you would see nitrogen excreted in the urine in the amount of 25 percent of the nitrogen they ate.
Although it is pretty easy and cheap to do a chemical scoring of any protein, it does not always accurately predict how digestible it is and how well the body can use it.
Chemical scoring also involves a procedure that may destroy certain amino acids and this may lead to inaccurate results. Plus, it doesn't count substances in a given protein that can make it less digestible, so it doesn't give you the full picture.
Biological Value (BV)
Biological value (BV) scoring uses in vivo testing. To find the actual amount of a given protein that will be used by the body, you measure how much nitrogen is lost when people go to the bathroom.
When measuring the BV of a protein source, two nitrogen studies are done. The first study measures how much nitrogen is lost from the body even when no protein is fed. This amount of nitrogen loss is assumed to be inevitable and that the body will naturally lose it no matter how much nitrogen is in the diet.
In the second study an amount of the protein is fed that is slightly below what is required. As before, the nitrogen losses are then measured, but this time they are compared to the amount of nitrogen consumed. To determine the actual BV of the protein, the results are then derived using this formula:
Net protein utilization (NPU) = (N retained / N intake) x 100
This method often involves animal test subjects and is more frequently used. Its drawbacks are that if a low NPU is obtained, it is impossible to know if it is because of a poor amino acid profile or low digestibility.
Protein Efficiency Ratio (PER)
Protein efficiency ratio (PER) is the best known procedure for deciding protein quality and is used in the United States for food labeling and setting the protein recommended dietary allowance (RDA). This method involves rats who are fed a measured amount of protein and weighed periodically as they grow. The PER is expressed as:
PER = weight gain (g) / protein intake (g)
The benefits of this method are its expense and simplicity. Its drawbacks are that it is time consuming, the amino acid needs of rats are not those of humans, and the amino acid needs of growing animals are not those of adult animals (growing animals and humans need more lysine, for example).
The PER is used to qualify statements about daily protein requirement in the United States. It's based on eating protein with a PER that is equal to or better than that of the milk protein casein; if the protein's PER is lower, you must eat more of it to meet the RDA.
Food labels have to take protein quality into consideration, using the PER of casein as a reference point. If a food has a protein quality equal or better than that of casein, the RDA is 45 grams. If the protein quality is less than casein you need 65 grams for the RDA.
You may be wondering if it makes any difference if you get your protein from a supplement or from food. Remember that by the time it gets absorbed into the bloodstream, all your body knows is how much of each amino acid was present in what you consumed.
If you have the money, it is certainly convenient to just drink down a high-quality protein supplement. Beyond that, it makes no difference what form you get your protein from, as long as it's a complete protein and sufficiently digestible.
Protein Digestibility-Corrected Amino Acid Score (PDCAA)
Protein quality can be measured by the quantity of amino acids. If a protein contains all the amino acids essential for life, it is called a complete protein and is given a high score.
Because some proteins are not as efficiently digested, there was a need to not only test for the amino acids in proteins but also for digestibility. This type of testing is called protein digestibility-corrected amino acid score (PDCAA). It is now a federally accepted standard for determining protein quality for preschool-aged children in the United States.
Some foods contain antinutritional factors. These factors, whether they occur naturally or are a result of heating or cooking, make it harder for the body to digest and absorb certain amino acids. The PDCAA method of scoring protein often overestimates the quality of foods containing antinutritional factors.13
The take-home message from all this is that arguments about which protein scored highest on this test or that test are really meaningless to the average well-fed athlete.
Knowing the truth about protein will not only save you money, but may also open up new opportunities for muscular gains. Knowledge is the key to effective supplementation with protein or any other supplement.
Don't let your purchasing decisions be controlled by false claims and misleading information. A wise man once said, "...know the truth, and the truth shall set you free." In this case, the truth will give you the freedom to make educated decisions about protein supplementation and the freedom to discern between marketing hype and honest manufacturers offering quality products.
- Newsholme, E. A., & Parry-Billings, M. (1990). Properties of glutamine release from muscle and its importance for the immune system. Journal of Parenteral and Enteral Nutrition, 14(4_suppl), 63S-67S.
- Young, V. R., & Marchini, J. S. (1990). Mechanisms and nutritional significance of metabolic responses to altered intakes of protein and amino acids, with reference to nutritional adaptation in humans. The American Journal of Clinical Nutrition, 51(2), 270-289.
- Bennet, W. M., Connacher, A. A., Scrimgeour, C. M., & Rennie, M. J. (1990). The effect of amino acid infusion on leg protein turnover assessed by L‐[15N] phenylalanine and L‐[1‐13C] leucine exchange. European Journal of Clinical Investigation, 20(1), 41-50.
- Castellino, P., Luzi, L., Simonson, D. C., Haymond, M., & DeFronzo, R. A. (1987). Effect of insulin and plasma amino acid concentrations on leucine metabolism in man. Role of substrate availability on estimates of whole body protein synthesis. Journal of Clinical Investigation, 80(6), 1784.
- Oddoye, E. A., & Margen, S. (1979). Nitrogen balance studies in humans: long-term effect of high nitrogen intake on nitrogen accretion. The Journal of Nutrition, 109(3), 363-377.
- Tipton, K. D., Ferrando, A. A., Phillips, S. M., Doyle, D., & Wolfe, R. R. (1999). Postexercise net protein synthesis in human muscle from orally administered amino acids. American Journal of Physiology-Endocrinology and Metabolism, 276(4), E628-E634.
- Millward, D. J. (1998). Metabolic demands for amino acids and the human dietary requirement: Millward and Rivers (1988) revisited. The Journal of Nutrition, 128(12), 2563S-2576S.
- Fryburg, D. A., Jahn, L. A., Hill, S. A., Oliveras, D. M., & Barrett, E. J. (1995). Insulin and insulin-like growth factor-I enhance human skeletal muscle protein anabolism during hyperaminoacidemia by different mechanisms. Journal of Clinical Investigation, 96(4), 1722.
- Fern, E. B., Bielinski, R. N., & Schutz, Y. (1991). Effects of exaggerated amino acid and protein supply in man. Experientia, 47(2), 168-172.
- Dragan, I., Vasiliu, A., & Georgescu, E. (1985). Effects of increased supply of protein on elite weight-lifters. Milk Proteins, 84, 99-103.
- Boirie, Y., Dangin, M., Gachon, P., Vasson, M. P., Maubois, J. L., & Beaufrère, B. (1997). Slow and fast dietary proteins differently modulate postprandial protein accretion. Proceedings of the National Academy of Sciences, 94(26), 14930-14935.
- Zempleni, J., & Kuroishi, T. (2012). Biotin. Advances in Nutrition: An International Review Journal, 3(2), 213-214.
- Sarwar, G. (1997). The protein digestibility–corrected amino acid score method overestimates quality of proteins containing antinutritional factors and of poorly digestible proteins supplemented with limiting amino acids in rats. The Journal of Nutrition, 127(5), 758-764.