Dietary ?bre is that part of food which cannot be digested in the gastrointestinal tract, although it can be metabolised in the colon by the micro-organisms there. Roughage falls into four groups: cellulose, hemicelluloses, lignins and pectins, found in unre?ned foods such as wholemeal cereals and ?our, root vegetables, nuts and fruit. It has long been known to affect bowel function, probably because of its capacity to hold water in a gel-like form. It plays an important role in the prevention of CONSTIPATION, DIVERTICULOSIS, IRRITABLE BOWEL SYNDROME (IBS), APPENDICITIS, DIABETES MELLITUS and cancer of the colon (see INTESTINE). At present, many western diets do not contain enough roughage.
n. a condition in which bowel evacuations occur infrequently, or in which the faeces are hard and small, or where passage of faeces causes difficulty or pain. The frequency of bowel evacuation varies considerably from person to person. Constipation developing in a person of previously regular bowel habit may be a symptom of intestinal disease and may require further investigation. Recurrent or longstanding constipation is treated by increasing fluid intake, *dietary fibre (roughage), *laxatives, or *enemas, and by withdrawing medications that promote constipation (such as opiates). Faecal impaction, the end-result of chronic constipation (more common in the elderly and the very young), often requires manual removal of the faecal bolus (faecal disimpaction), sometimes under an anaesthetic.... constipation
(roughage) nonstarch polysaccharides (NSP), which cannot be digested and absorbed to produce energy; specifically, sources of NSP that do not contain lignin or resistant starch. Fibre is divided into two types: insoluble (cellulose and hemicelluloses) and soluble (pectins). Highly refined foods, such as sucrose, do not contain dietary fibre. Foods with a high fibre content include wholemeal cereals, vegetables, nuts, and fruit. A diet high in insoluble fibre (e.g. wheat bran, wholegrain and wholemeal bread and cereals) may help prevent bowel diseases, such as constipation, diverticulitis, and colon cancer. Soluble fibre (e.g. oats, barley, beans, pulses, fruit, and vegetables) slows the reabsorption of *bile salts and so helps to lower cholesterol as well as dampening the glycaemic response to glucose (see glycaemic index). A high-fibre diet used to be the first-line advice for irritable bowel syndrome; however, a low *FODMAP diet can be more effective.... dietary fibre
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