Irritable Bowel Syndrome Message Boards | SF foods, SFS, and gas - here's what I think, let me know if I'm right

Something that comes up on the Board repeatedly is the idea that Soluble Fiber foods and/or Soluble Fiber Supplements cause gas. I did some poking around and I think I understand what's going on here. If I've got something wrong, please let me know. And there are some things I still don't understand, so if anyone can fill in the blanks, I'd appreciate it.

Intestinal gas is caused by different things. Two simple ones are swallowing air (perhaps eating too fast, gulping food down) and carbonation (those little bubbles have to go somewhere). In addition, the digestion (or non-digestion) of certain types of foods also produces gas. As I understand it, if a food makes it through the stomach and small intestine and then into the large intestine without being digested, it will be fermented by the bacteria that live in the large intestine. The bacteria produce gas as a waste product. Apparently only carbohydrates have the potential to produce gas in this manner; fats and proteins do not.

The carbohydrates that produce gas do so for three different reasons:

1) Some foods contain sugars, not table sugar, but complex sugars. The complex sugars that can cause gas are: raffinose, lactose, fructose, and sorbitol. These cause gas because the body lacks the enzymes to digest them before they make it to the large intestine. Here is where digestive enzymes can help. Beano can help the body break down some of these sugars before they reach the large intestine. Beano does not help break down lactose, but Lactaid can do so. (Note that Lactaid does not help with the dairy proteins that are problematic for IBSers.)

2) Most starches cause some gas as they break down in the large intestine. Rice is the only exception. I haven't seen anything that will help prevent this.

3) Soluble Fiber. This always passes undigested into the large intestine. In fact, that is the benefit of it. However, this means those little bacteria fall upon it with glee, gobble it up, and produce gas. This is true for both soluble fiber foods and, apparently, for most (if not all) soluble fiber supplements. Based on my reading, it looks like as the bacteria in the gut adjust to an increase in soluble fiber, the amount of gas almost always decreases. Digestive enzymes will not help with this.

Soluble Fiber Supplements are where things get a little tricky. Some SFS seem to be terrible as far as gas is concerned. Inulin and psyllium are two that apparently ferment like crazy, producing a lot of gas. Some, like Citrucel, claim not to ferment at all. I don't really follow this, since from what I read all soluble fibers ferment. From what I've read on this Website, it seems that Acacia falls somewhere in between. It does act as a prebiotic which means it must encourage bacteria which means it must produce some gas, but it seems to produce far less than inulin or psyllium.

Apparently, then, soluble fiber does produce gas although it appears that as the body adjusts the amount of gas decreases. So I would say that if you want to add an SFS, the advice to start with a very low dose and increase slowly is super important. And remember that if you are having trouble with gas it's not necessarily because of the soluble fiber - other foods can cause gas, also. Try a digestive enzyme to help ward off those problems.

In addition, fermentable soluble fiber is important to get even apart from the IBS benefits of soluble fiber and soluble fiber supplements. This fermentation is what produces short chain fatty acids. I just skimmed over the information on these, but they sound like the best thing since sliced bread. This is what helps keep down lipid levels, for example.

A few odds and ends of information:
- It sounds like anti-gas agents such as simethicone apparently help with stomach gas but don't have any impact on intestinal gas.
- Foods that are high in sulfur like garlic, onions, leeks, broccoli, cauliflower, cabbage and Brussels sprouts can make gas foul-smelling. Since some of these also contain raffinose, you get a double whammy: lots of gas *and* a bad smell.
- Some people suggest that activated charcoal tablets may help with gas in the colon.
- Because people with IBS often have visceral hypersensitivity (very sensitive guts) even a small amount of intestinal gas may be more painful for us than for non-IBSers.

My main source for this was web page

HTH.

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