Diarrhoea and its dietary management

Definition of diarrhoea

Diarrhoea is defined by the World Health Organization as having three or more loose or liquid stools per day, or as having more stools than is normal for that person. Acute diarrhoea is defined as an abnormally frequent discharge of semisolid or fluid faecal matter from the bowel, lasting less than 14 days, by World Gastroenterology Organisation (Wilson, 2005).

Types of diarrhoea

Patel et al (2009), classified diarrhoea into four different types based on their characteristics.

Secretory diarrhoea

Secretory diarrhoea means that there is an increase in the active secretion, or there is an inhibition of absorption. There is little to no structural damage. The most common cause of this type of diarrhoea is a cholera toxin that stimulates the secretion of anions, especially chloride ions. Therefore, to maintain a charge balance in the lumen, sodium is carried with it, along with water. In this type of diarrhoea intestinal fluid secretion is isotonic with plasma even during fasting. It continues even when there is no oral food intake.

Osmotic diarrhoea

Osmotic diarrhoea occurs when too much water is drawn into the bowels. If a person drinks solutions with excessive sugar or excessive salt, these can draw water from the body into the bowel and cause osmotic diarrhoea. Osmotic diarrhoea can also be the result of maldigestion (e.g., pancreatic disease or Coeliac disease), in which the nutrients are left in the lumen to pull in water. Or it can be caused by osmotic laxatives (which work to alleviate constipation by drawing water into the bowels). In healthy individuals, too much magnesium or vitamin C or undigested lactose can produce osmotic diarrhoea and distention of the bowel. A person who has lactose intolerance can have difficulty absorbing lactose after an extraordinarily high intake of dairy products. In persons who have fructose malabsorption, excess fructose intake can also cause diarrhoea. High-fructose foods that also have a high glucose content are more absorbable and less likely to cause diarrhoea. Sugar alcohols such as sorbitol (often found in sugar-free foods) are difficult for the body to absorb and, in large amounts, may lead to osmotic diarrhoea.  In most of these cases, osmotic diarrhoea stops when offending agent (e.g. milk, sorbitol) is stopped.

Exudative diarrhoea

Exudative diarrhoea occurs with the presence of blood and pus in the stool. This occurs with inflammatory bowel diseases, such as Crohn’s disease or ulcerative colitis, and other severe infections such as E. coli or other forms of food poisoning.

Inflammatory diarrhoea

Inflammatory diarrhoea occurs when there is damage to the mucosal lining or brush border, which leads to a passive loss of protein-rich fluids and a decreased ability to absorb these lost fluids. Features of all three of the other types of diarrhoea can be found in this type of diarrhoea. It can be caused by bacterial infections, viral infections, parasitic infections, or autoimmune problems such as inflammatory bowel diseases. It can also be caused by tuberculosis, colon cancer, and enteritis.

Causes of diarrhoea

The most common cause of diarrhoea is a virus that infects the gut. The infection usually lasts for two days and is sometimes called “intestinal flu” or “stomach flu.” Diarrhoea according to King, et al (2003) may also be caused by:

  • Infection by bacteria (the cause of most types of food poisoning)
  • Infections by other organisms
  • Eating foods that upset the digestive system
  • Allergies to certain foods
  • Medications
  • Radiation therapy
  • Diseases of the intestines (Crohn’s disease, ulcerative colitis)
  • Malabsorption (where the body is unable to adequately absorb certain nutrients from the diet)
  • Hyperthyroidism
  • Some cancers
  • Laxative abuse
  • Alcohol abuse
  • Digestive tract surgery
  • Diabetes
  • Competitive running

Diarrhoea may also follow constipation, especially for people who have irritable bowel syndrome.

Symptoms of diarrhoea

Symptoms of diarrhoea according to Ejemot, et al (2005) can be broken down into uncomplicated (or non-serious) diarrhoea and complicated diarrhoea. Complicated diarrhoea may be a sign of a more serious illness.

Symptoms of uncomplicated diarrhoea include:

  • Abdominal bloating or cramps
  • Thin or loose stools
  • Watery stool
  • Sense of urgency to have a bowel movement
  • Nausea and vomiting

In addition to the symptoms described above, the symptoms of complicated diarrhoea include:

  • Blood, mucus, or undigested food in the stool
  • Weight loss
  • Fever

Dietary management of diarrhoea

According to Kasper, et al (2005), dietary management for diarrhoea include:

  • Drink clear fluids – broth, water and juices – for the first twelve hours of your diarrhoea.
  • After 12 hours of liquids only, follow the BRAT diet – bananas, rice, applesauce, and toast.
  • Green bananas are best for diarrhoea.
  • Plain toast is a good idea as this will further dilute and absorb up the tainted fluids that are stored up in your stomach.
  • Limit insoluble fibres. Insoluble fibres are called “insoluble” because they do not dissolve in water. Insoluble fibres accelerate the movement of food through the GI tract. Soluble fibres, such as pectin (found in applesauce), slow the movement of food through the GI tract by forming a gel when combined with water. Soluble fibres have a property called viscosity, and fibres with a higher viscosity are more beneficial for diarrhoea.
  • Eliminate foods that might be contributing to your diarrhoea, such as high-fructose foods, sugar-free foods sweetened with sugar alcohols, and dairy products. Dairy products may worsen diarrhoea in people who are not lactose-intolerant because food usually travels through the intestines more quickly during diarrhoea, which may reduce the absorption of lactose. The unabsorbed lactose may then draw water into the bowels.
  • After recovery, try some yogurt. If the diarrhoea is not caused by antibiotics, yogurt with live cultures is often helpful to restore the balance in your digestive tract. Often the cause of antibiotic-related diarrhoea is an overgrowth of the clostridium bacteria, and “good” bacteria often help keep that in check.


Diarrhoea, no matter the form it appears certainly is a life threatening situation that must be taken seriously. The greatest way to properly manage it is to ensure that it did not happen in the first place by avoiding the contamination of food items through observing proper personal hygiene. However, when diarrhoea occurs, there should be an immediate action to stopping it through the use of the BRAT diet.


Ejemot, R.I.; Ehiri, J. E.; Meremikwu, M. M. & Critchley, J. A. (2008).  Handwashing for Preventing Diarrhoea. Cochrane Database System. Review (1): CD004265.

Kasper, D. L.; Braunwald, E.; Fauci, A. S.; Hauser, S. L.; Longo, D. L & Jameson, J. L. (2005). Harrison’s Principles of Internal Medicine. New York: McGraw-Hill.

King, C. K.; Glass, R.; Bresee, J. S. & Duggan, C. (2003). Managing acute gastroenteritis among Children: Oral Rehydration, Maintenance and Nutritional Therapy. MMWR Recomm. Rep. (RR-16): 1 – 16.

Patel, M. M.; Hall, A. J.; Vinjé, J. & Parashar, U.D. (2009). “Noroviruses: a comprehensive review”. Journal of Clinical Virology 44 (1): 1–8.

Wilson, M. E. (2005). “Diarrhoea in nontravelers: risk and etiology”. Clin. Infect. Dis. 41 (Suppl 8): S541–6.

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