A Lesson in Protein Digestion

You’re in the protein bar aisle looking for that perfect protein bar to fuel your recovery from a hard workout or run.  Or sometimes an even more daunting task: you’re looking at all of the tubs of protein powder, touting 100% this and max protein content that.  Let’s face it, not everyone knows how much protein they should be consuming on a daily basis and what the best protein product really is for them.  To understand why not all protein is created equal, the first thing we need to do is take a step backwards and take a look at how the protein (bar, powder or any other form) you are putting into your body is digested.  This is the key to proper protein consumption.  We have to warn you, it’s not always a pretty process, but if done correctly and with the right type of protein, you will achieve max results without all of the annoying side affects some proteins can cause.  So, let’s get into protein digestion:

Protein digestion begins in the stomach and proceeds down the small intestine through the ileum where any remaining protein enters the colon and is consumed by our gut bacteria. Undigested protein is what generates that infamous gas, bloating and intestinal cramps, leading to pain and even diarrhea if excessive.  NO THANKS!

In order to be absorbed, all protein, now this is ALL PROTEIN, with the exception of a few very specific residues, must be reduced in molecular size to single aminos and the smallest peptides, called dipeptides, tripeptides and possibly quadrapeptides which contain 2, 3 or 4 amino acids respectively. This process is called protein hydrolysis and the end product is called a hydrolysate. Protein that is not completely hydrolyzed cannot pass into the blood for delivery throughout the body. Animal proteins contain hundreds of amino acids and plant proteins can contain more than a thousand. But in order for your cells to accept delivery, they must all be significantly hydrolyzed.

When protein enters the stomach it is bathed in hydrochloric acid and pepsin, which begin the process of digestion. There is no protein absorption, and only about 2% of the necessary breakdown occurs in the stomach. The stomach is where the surface peptide bonds are broken and the entire mass is stirred into chyme that is suitable for entrance into the small intestine. Once in there, proteases and other enzymes are released and the process of hydrolysis moves into full activity.

There are 10 known different amino acid transporters required to carry 20 aminos, yet only one transporter, called PEPT-1 is needed to convey over 8,400 different di and tripeptides into the blood. As you can probably guess, this means that there is a much greater efficiency in moving di and tripeptides into the blood than there is for single amino acids, which require specialized transporters.

The first 6-8 feet of small intestine is where there is an abundance of the PEPT-1 transporters and relatively fewer amino acid transporters. It is a solid fact that we are set up to capture di and tripeptides quickly.

As protein moves down into the ileum section of the small intestine there are more amino acid transporters relative to the PEPT-1 transporters, a fact that again affirms peptides over amino acids as the primary form of protein absorption and nutrition in humans. Protein then moves past the ileum where digestion slows and finally, any remnants move into the colon for excretion.

This is the usual process for whole protein digestion, which typically delivers much of its protein into the blood as free aminos instead of di and tripeptides, and depending on a host of factors, can create excess undigested protein and the accompanying gas and other undesirable effects we spoke about earlier; ] including the increased loss of excessive dietary amino acids by the liver as toxic waste; a process that further decreases the nutritive value of any dietary whole protein.

The protein used in Power Crunch’s Proto Whey protein powder is called High-DH hydrolysates.  This type of protein presents quite a different offering after moving out of the stomach. Di and tripeptides are immediately absorbed while the balance of small peptides rapidly complete their breakdown and are absorbed a short while later offering complete and rapid protein absorption.  Hence optimal protein absorption and no nagging side effects.

We hope this has been an informative (and not too disturbing) lesson on how protein digestion works in the body – an important fact to understand when choosing the proper protein product to consume.