The tutor has wondered about fibre ever since he heard about soluble fibre.
Back in the early 90s, when I was in university so cut off from day-to-day culture (no TV, no money, no time), a few snippets still did reach me. One was the term “soluble fibre.” I was highly skeptical; how could fibre, undigestible by definition, yet be soluble?
At an early age I was taught that fibre passes through the intestines, keeping the bowels loose and the stool easy to pass. It can do so because it’s not digestible. At the same time, it holds water, keeping the stool soft. Therefore, it speeds the movement of material through the gut. To do so, wouldn’t you expect it to be insoluble?
Well, the insoluble fibre is the kind I’ve just described above. However, soluble fibre also exists, but serves a different function. In contrast with insoluble fibre, soluble fibre slows food’s exit from the stomach. Apparently, as it dissolves in water, it forms a complex with the water molecules, giving them more inertia. Possibly, cholesterol can get stuck in the complex as well, making it less likely to be absorbed. Anyhow, the effect is that, with the soluble fibre binding together the water molecules in which it’s dissolved, the liquified food in the stomach is more sluggish. Therefore, it stays in the stomach longer. One result is feeling “full” for a longer duration after eating. The other is a slower release of glucose into the bloodstream, which may help offset – or even prevent – symptoms of diabetes.
The sources of both soluble and insoluble fibre are numerous. A variety of fresh fruits and vegetables, plus a variety of whole grains, will likely avail plenty of both. Here’s a fun fact, though: oat bran provides soluble fibre, while wheat bran provides insoluble. I seem to recall, from the 90s to the early 2000s, an increased focus on oat bran rather than just bran.
Soluble and insoluble fibre: now we know:)
Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.