Doctor, every time I do *this*, it hurts!

The correct response is either:-

1) Go to hospital and get that broken finger fixed, or
2) Stop doing *that*!

There seem to be a lot of people out there who are having problems with wheat gluten (gliadin), casein and other proteins. As Matt Lalonde said in The Science Behind the Paleolithic Diet, some proteins are harder to digest than others.

Here's a hard to digest protein:-


It's raw albumin (egg white protein). As mentioned in As sure as Eggs is Eggs....., raw albumin is poorly absorbed, compared to cooked albumin. To digest the above protein requires peptidase enzymes (pepsin, trypsin and chymotrypsin) to break the peptide bonds. This has to be done from the outside inwards, so a large, heavily-folded protein takes a long time to break down into individual amino acids. Cooking albumin changes the 3-D structure - this is called denaturing. Cooked albumin digests much faster than raw albumin, which is why it's much better absorbed. Cooked proteins are generally faster to digest than raw proteins, unless they're burned to a crisp on a barbecue!

In a person with a healthy gut, partially-digested proteins are not absorbed, as the molecules are too large to pass through the tight junctions in the small intestine. They just ferment, producing malodorous wind. In a person with impaired gut permeability, partially-digested proteins pass through the loose junctions and get into the blood, provoking an immune response. This is not good, so Keep 'em tight.

People who suffer ill-effects after eating certain proteins may either have the wrong genes (e.g. coeliac disease), or have impaired gut permeability. The former isn't fixable but the latter may be. In the meantime, if eating "X" hurts, don't eat "X"!