Let’s love fibre- Chapter 2: Insoluble Fibre
Welcome to the second part of the fibre series!!
Insoluble fibre is the part of dietary fibre that cannot be dissolved in water. Insoluble fibre foods include brown rice, wheat, legumes (eg. lentils, chickpeas), potatoes, nuts, seeds , brussel sprouts, broccoli and cauliflower. Also, many fruits and vegetables (eg. prunes, beans) contain both soluble and insoluble fibre.
Insoluble fibre could promote healthy bowel movements.
Comparing to soluble fibre, insoluble fibre is fermented in the bowel to a much smaller degree. This is why insoluble fibre particles reach the large instenine mucosa and create an irritating effect due to their “rough” composition. The result is the production of mucus and water in the large bowel and the increase of stool water content. Hydrated stool is softer, bulkier and easier to pass. Since large intestine cells can absorb water and reduce the stool water content, insoluble fibre is important to prevent stool dehydration and promote regular bowel movements .
A diet rich in insoluble fibre could decrease the risk of diverticulitis.
A diet rich in both soluble and insoluble fibre could reduce the diverticulitis risk . In fact, lower fibre intake after the industrilization of several areas could possibly be a factor of the increased diverticultis prevalence. Consuming insoluble fibre though has recently been associated with a decreased diverticulitis risk more strongly comparing to soluble fibre intake. The association was significant only for fibre coming from fruit and cereal .
Food processing could affect insoluble fibre structure .
- Heat could break glycosidic linkages in fibre molecules and that could turn insoluble fibre into soluble.
- Boiling vegetables seems to increase their total fibre content, probably because of the loss of other constituents.
- Milling cereal grains can partly break down the endosperm’s insoluble fibre. As a result, fibre can be more easily digested by upper gastrointesinal tract enzymes or be fermented by gut bacteria.
- Excessive milling may also reduce the size of fibre molecules to the point where their properties could be negatively affected. Data is still inadequate though, so further research is required.
Thank you for reading. Chapter 3 will be about the potential effect of fibre on appetite and weight management!
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