T Nation

Digestibility of Raw Eggs


#1

Over the past two months I've found raw eggs an easy and convenient way to get calories down, especially at work when i don't have time to cook. I aim for about 20 a day, which I gently mix with a tablespoon of olive oil, and one of cream for taste.

The only information I've found on the digestibility of raw vs cooked eggs is http://jn.nutrition.org/cgi/content/full/128/10/1716 this.

This study is problematic, the way I see it, and doesn't apply to me because:
-The participants fasted before consuming the eggs
-The ratio of white to yolk was 1/4 in favour of the white
-The eggs weren't consumed with anything else, which could have made them stay in the gut longer, increasing absorption

The study finds that only about 50% of the protein from raw eggs are absorbed.other than cooking, what could make the digestion of them more efficient?

I'm thinking:
-Apple cider vinegar to help with the breakdown
-Ginger tot stimulate bile secretion, helping in breakdown
-Adding fat to the mix, like olive oil or cream
-Eating something solid before, making the eggs tay longer in the gut


#2

If you lack the specific enzyme required, how are any of these going to make a difference?


#3

"The higher digestibility of cooked egg protein presumably results from structural changes in the protein molecule induced by heating, thereby enabling the digestive enzymes to gain broader access to the peptide bonds. It has been suggested that the reduced digestibility of raw egg white is at least partially related to the presence of trypsin inhibitors in raw egg white (Matthews 1990). Ovomucoid is quantitatively the most important trypsin inhibitor (Gilbert 1971, Kassell 1970). Ovomucoid, however, does not react with human trypsin and, moreover, is relatively heat stable (Kasell 1970). Whether other egg trypsin inhibitors (e.g., ovoinhibitor or papain inhibitor) interfere with the digestibility of unprocessed egg white protein is unknown.

Interestingly, the yield of endogenous nitrogen after ingestion of the raw protein meal (i.e., 0.2 g N) was significantly lower compared with the cooked protein meal. This finding is in accordance with a recent study in which it was demonstrated that undigested protein, in contrast to digested protein, only weakly stimulates gallbladder emptying and pancreatic enzyme secretions (Thimister et al. 1996)."

My understanding is this, you don't lack the enzyme(s) to digest the raw eggwhites, the malabsorption is from too little enzyme interacting with the peptide bonds due to the quality of the egg protein in its raw state - cooking changes this, giving the enxzymes 'broader access'.

Could other means also do this, namely mixing in other agents that separate the contents, giving the enzymes that access, or increase the time it stays in the gut, more time = more exposure?


#4

So far, the best solution I've come up with is to just cook the damn whites some and eat them, and drink the yolk. If I'm at work though, I'll have to drink it all.


#5

Just hard boil them and eat the whites not the yolk if your worried about eating yolks. Personally I like hard boiled eggs and I think they make a good snack.


#6

If your taking in 20 eggs a day then cooking them is optimal for sure. I have an egg with my morning shakes 4 days a week so it's not going to impact me as much.

Cook'm. Don't make excuses for lack of time when you did all this research :wink:


#7

Have you heard of egg protein powder? I belive it's the product of cooked eggs, so digestability wouldn't be an issue. A carton of eggs would be cheaper (if you pay less than ~$3.50), but you get convenience and no issues with digestability.


#8

Thank you for posting that study. Other similar work that I had read before failed to specify whether the whites and yolks were consumed as is, or homogenized (e.g. scrambled.) And ordinarily when writing materials and methods, one doesn't fail to specify a relevant step that was done, so one was left with the possibilities of careless writing if there were any homogenization but with this left unsaid, or better writing and there having been no homogenization.

Lack of homogenization therefore remained a possible explanation, given no specific statement on it.

This study however makes plain that they homogenized the eggs.

I don't think that the objections you raise make likely equally good bioavailability as cooked when consumed the way that you do. There might well be a difference in percentage as the percentage yolk is different, but there seems no clear mechanism why the problem with bioavailability of the albumin would be completely (if at all) solved with more yolk. A molecule of albumin floating in solution is not going to be treated differently by enzymes just because another molecule someplace else happens to be of yolk protein instead of from the whites.

The study found rate of gastric emptying to not be the cause.

So I don't think any of your methods would work.

Sadly, this means I ought to start bothering to cook eggs rather than having them raw. Pain in the ass.


#9

Looking at it from an anecdotal standpoint, it seems that the white is only there for the protection of the yolk, thus containing two agents that defend it from the growth of bacteria - indigestibility of protein and an anti-vitamin.

If I have the time, I now separate the yolk and the white, gently fry the white and drink the yolk. It'll be interesting to see the effects of this, as it could potentially mean 60 grams of protein a day which previously was undigested, and more B-vitamins available.


#10

For convenience (as previously stated), I recommend hardboiling the eggs. You can prepare them ahead of time and you dont have to worry about breakage.