This is a huge problem for a lot of us. It’s not that we don’t go daily – for those of us who do – but when we go it’s only partially complete. Anyone with this condition knows that this often leads to IBS symptoms as the day progresses. Non-IBS people get constipation as well, but don’t have the symptoms that we do. This could be because they effectively digest their food. If they suffer from constipation, they just get constipation. If a non-IBS person has constipation, unless they tell you, you wouldn’t know.
IBS sufferers on the other hand know that there are certain carbs they can’t digest well. This means that the nutrients of these carbs escape digestion through the villi of the small intestine. These food molecules continue to travel through the small intestine and colon, feeding bacteria. The fermentation creates Short Chain Fatty Acids (SCFAs) which are healthy in fairly small doses in the colon but deadly to epithelial cells in the small intestine, where they don’t belong.
As undigested stool passes through the small intestine and colon, it will increasingly fill with gas. This is the origin of gas in IBS. Dr Mark Pimentel pioneered a study which showed that about one third of us produce methane, which causes constipation. Other people convert methane to hydrogen, leading to diarrhea.
This could account for all the different sub-groups in IBS. It’s still the same underlying cause – maldigested food – but it affects people differently according to their bacterial make-up.
Methane can act as a neurotransmitter, meaning it can affect the muscular contractions of the colon, or peristalsis. On a physical level, pockets of gas can also impede the passage of stool. The end result is that a lot of gas in the colon will lead to an inefficient bowel evacuation.
Our gut has its own brain, the enteric nervous system. But the gut and our brain are united, in one organism. If we have had a long history of difficult and time consuming evacuations, then this habit might be hard to shake, for both us and our colon.