There can be many causes of constipation, which may occur singularly or with other causes. Dietary causes of constipation can be from under nutrition, anorexia, inadequate fluid, dehydration, a low fiber diet, chewing or swallowing issues. There can also be many other causes of constipation such as: metabolic (e.g. diabetes), drugs (e.g. opoids), endocrine (e.g. hypothyroidism), neurological (e.g. MS, spinal injuries), psychiatric (e.g. anxiety, depression), structural abnormalities (e.g. rectal and anal disorders) or disease (e.g. Irritable Bowel syndrome, coeliac disease, colon cancer, diverticulitis, inflammatory bowel disease). But more commonly constipation is caused by reduced physical activity and inadequate dietary intake of fibre, carbohydrates and fluids (1). Risk factors for constipation are females (5 – 10 times more likely to have constipation compared to men), old age, low fibre diets, sedentary life style, malnutrition, poly-pharmacy and a low socioeconomic status (2).
Upright posture and exercise have been shown to promote colonic motility. It has been postulated that exercise may increase gastrointestinal motility and the mechanical bouncing, assist with digestive processes (3, 4) . Low physical activity is associated with a twofold increase in constipation risk (2). Prolonged bed rest and immobility are often associated with constipation. Try to be active at least 30 minutes every day to ensure the upright posture and moving of the body assist with regular bowel movements.
The very act of eating stimulates the bowels to move rhythmically. Starvation and fasting can reduce the motility of the gut, therefore it is advised to eat regular meals and snacks throughout the day. Diets containing fibres (25 – 30 g daily) will result in large, soft stools, which move rapidly through the intestine. The frequency of faeces is related to bulk and viscosity. The bulk is largely determined by the fibre intake and the viscosity is usually inversely related to bulk (1). If someone has a low fibre diet then gradually increasing the fibre intake by 5 g per day each week until the daily recommended intake is reached (5). If fibre is added to quickly this may cause excessive gas and bloating.
Regular bowel habits involve trying to empty bowels at the same time of the day. The optimal times to have a bowel movement typically are soon after waking, and after meals when colonic activity is greatest (5). People with constipation are encouraged to attempt defecation first thing in the morning when the bowel is more active, and 30 minutes after meals to take advantage of the gastrocolonic reflex (5).
Laxatives maybe useful in certain situations to relieve constipation or assist regular motility, especially if opioids or other medications which may lead to constipation are used (5). There are several laxatives that can be considered depending on the symptoms such as; bulk laxatives (e.g. fibres), stool softeners (emollients, which allow water to enter the bowel more easily), osmotic laxatives (which cause secretion of water into the intestinal lumen by osmotic activity), stimulant laxatives (increase intestinal mobility and secretion of water into the bowel) and prokinetic agents (help with slow transit time). Bulk laxatives are most commonly used as they may contain soluble fibre (psyllium, pectin or guar) or insoluble (cellulose) fibre products (5). These are hydrophilic absorbing water from the intestinal lumen to increase stool mass and soften the stool consistency. As with increasing dietary fibres bloating and excess gas production may be a complication of bulk laxatives. Not all patients will be helped by bulk laxatives such as; slow transit constipation or anorectal dysfunction.
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1. Arnaud, M. J. (2003). Mild dehydration: a risk factor of constipation?. European journal of clinical nutrition, 57(S2), S88.
2. Alame, A. M., & Bahna, H. (2012). Evaluation of constipation. Clinics in colon and rectal surgery, 25(1), 5.
3. Dukas, L., Willett, W. C., & Giovannucci, E. L. (2003). Association between physical activity, fiber intake, and other lifestyle variables and constipation in a study of women. The American journal of gastroenterology, 98(8), 1790.
4. De Oliveira, E. P., & Burini, R. C. (2009). The impact of physical exercise on the gastrointestinal tract. Current Opinion in Clinical Nutrition & Metabolic Care, 12(5), 533-538.
5. Hsieh, C. (2005). Treatment of constipation in older adults. Am Fam Physician, 72(11), 2277-84.