We’ve all watched that famous scene of Rocky Balboa cracking copious amounts of raw eggs into a glass, and then slamming it down before stepping out the door to begin his run. Most of you reading this article are probably well aware of why he did this, however, was this actually the best approach? Was Rocky limiting his muscular “gains” by choosing to consume them in raw form, instead of cooking them?
Rocky is a huge source of motivation and inspiration for me, and Sylvester if you’re reading this, no disrespect, but research shows us that the protein in raw eggs, is significantly less digestible, compared to it’s cooked counterpart.
Lets take a look at a study…
Digestibility of Cooked vs. Raw Egg Protein in Humans
(I will cite the full study at the end of this article for those interested)
Essentially in this study, the researchers wanted to look at 3 main things (I am only going to cover 2 of them here, because the 3rd is irrelevant to this article):
1. They wanted to determine the amount of nitrogen which went un-digested after consuming a meal containing a sufficient amount of egg protein.
2. They wanted to see if heat-pretreatment (aka cooking) the eggs, increased the efficiency of the protein’s digestion and absorption.
How They Performed the Study
The researchers took 5 people (subjects), otherwise healthy besides having an ileostomy, and had them consume 2 identical meals containing both egg-whites and egg yolks (meal macros were: 25 grams protein, 5.56 grams fat, negligible carbs).
The only difference between the 2 meals, was that one was raw, uncooked egg-whites/egg-yolk, and the other egg-whites/egg-yolk, were cooked (each meal was exactly the same other than this).
Without getting into the nitty-gritty details of how they assessed the subjects (again, the full study is cited at the end of this article), the researchers had them come into the lab after having not eaten anything for 12 hours, and then fed them one of the two meals described above. From here, the researchers monitored the subjects off-and-on for the next 24 hours. They waited 1 week, and then did this same thing again, however this time with the other meal.
What They Found…
They actually found a couple of very interesting things:
The true digestibility of raw egg protein was significantly less, compared to that of cooked egg protein. On average, the amount of raw egg protein that was absorbed, was only 51%, compared to almost 91% of the cooked egg protein.
This provides us with two very interesting details:
1. Almost 50% of the 25 grams of raw egg white protein was unabsorbed. This means, you are only “getting” about 12.5 grams of protein, compared to the 25 grams you thought you were getting.
2. The true digestibility of cooked egg protein is only 91%. Although 91% sounds like a lot, and it is, it still isn’t 100%, which is what many people teach the digestibility of egg protein is.
What’s the Reason for the Difference?
The researchers speculated that the higher digestibility of cooked egg protein may be due to structural changes in the protein molecule from heating it. These changes may enable our digestive enzymes to gain greater access to the peptide bonds. Further, the researchers suggested that the reduced digestibility of raw egg white, is at least partially due to the presence of trypsin (a digestive enzyme that breaks down protein) inhibitors, contained in raw egg white.
Overall, this looked to be a pretty sound study. There were only two major downsides I noticed with it: One, was the small number of subjects (5), and the other, was that the egg protein was eaten in isolation, and not in conjunction with other foods, which is how we normally consume food (as a part of a meal). This second limitation is purely speculation, and is based on the notion that if the egg protein were eaten alongside other food sources, different digestive enzymes which would have been secreted, may have been able to increase the digestibility of the raw egg protein. However, given the amount of control the researchers had over the study and these participants, plus the methods they used to collect and analyze the data, these results look promising.
Take Home Message
Whatever our goal is, building new lean-tissue, preserving the loss of muscle while dieting, chasing a new 1 RM, protein is important. This is true for both quantity and quality, and anything that interferes with either of these two, can potentially effect the outcome of achieving our goal. I didn’t write this article to try to convince you to never eat raw eggs. I simply wanted to provide you with information, so that you can better make the decision for yourself, about what approaches you’d like to use.
I hope you benefited, and enjoyed reading this article. If there is anything you’d like me to write about, feel free to leave it in the comments section below.
Evenepoel P, Geypens B, Luypaerts A, Hiele M, Ghoos Y, Rutgeert P. Digestibility of cooked and raw egg protein in humans as assessed by stable isotope techniques. J Nutr 1998;128:1716–22.