4.4 Fibre

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As we outlined in the last section, plant fibre is made up largely of cellulose, but also contains many other complex plant structural polysaccharides. We do not digest fibre; rather it passes through the digestive tract relatively unchanged. In doing so however it does have an important action. Insoluble fibre provides bulk to our intestinal contents and soluble fibre has a water-holding capacity keeping our intestinal contents and stools moist. Plant fibre contains a mix of insoluble and soluble fibre.

The provision of bulk by consuming enough fibre in the diet (current Government health guidelines suggest minimum of 12-18g per day for UK adults) is very important to allow the proper action of the intestinal wall as it works physically upon the food, mixing it, and moving the contents through the intestinal system. Without this bulk we become constipated or have a slower rate of transit (i.e. do not poo so regularly!). Partially digested food that take longer than is healthy to travel through the digestive tract may lead towards a state called putrefactive fermentation, where protein rich foods and other digestive health changes may disrupt the balance of gut bacteria, described as the state of dysbiosis. This has health implications for the digestive tract and throughout the body, more or which will be discussed in Module 7 on gut health.