Anyone on a Paleo diet might notice that their symptoms are getting worse. They’ve given up grains, and possibly starches & FODMAPs as well, but their IBS is just as bad as it ever was. This could be due to the little-known fact that meat can ferment in the colon.
Not all meat and fish are completely digested in the stomach. Up to 20% of animal protein can escape digestion and ferment in the colon. Sulphur is a major component of protein. Bacteria metabolise the proteins in undigested meat, causing hydrogen sulphide, or rotten egg gas.
Hydrogen sulphide can also damage the intestinal wall. A high meat diet might be a factor in colitis and inflammatory bowel disease.
So meat can be highly fermentable, and inflammatory, for some people, particularly if you eat a lot of it. Most of us can tolerate the sulphur in meat and fish as long as we don’t eat too much of it. It’s believed the higher the intake of meat the higher the fermentation potential in the colon.
So meat isn’t altogether the safe IBS food we’re told it is. We all have an individual threshold for the amount of sulphur we can ingest, the same as we all have a threshold for FODMAPs and starch. If we overdo any of these foods, IBS symptoms can occur.
I try to limit animal protein to 1 serving per day.
The problem with a Paleo / low starch / low FODMAP diet that excludes all grains, nuts etc (which are calorie rich) is that the only things left to eat are low fermentable vegetables and animal protein. We find we’re eating more and more animal protein to satisfy the hunger, as vegetables just aren’t that filling. None of this is easy.