Definition
Diarrhea is not a digestive disease in itself, but rather a symptom of an underlying condition. It generally involves the sudden and frequent passage of liquid stools. Diarrhea can lead to significant loss of fluids and electrolytes (e.g., sodium, magnesium, chloride, potassium), sometimes associated with dehydration. It may be accompanied by abdominal and perianal pain, gas, cramps, incontinence, weakness, nausea, vomiting, and fever.
Types
Diarrhea can be acute or chronic, depending on its duration. Acute diarrhea lasts less than a week and its most common causes include viral, parasitic, or bacterial infections (e.g., gastroenteritis) and food poisoning. Chronic diarrhea lasts more than four weeks and its most common causes include irritable bowel syndrome and Crohn's disease.
Classification
There are four classes of diarrhea, depending on their cause:
Osmotic diarrhea
Osmotic diarrhea results from the consumption of substances that are poorly or not absorbed. When these substances are present in excess in the intestine, they retain water, leading to the passage of liquid stools. Some causes of osmotic diarrhea include carbohydrate malabsorption (e.g., lactose intolerance), excessive consumption of poorly absorbable carbohydrates (e.g., fructose), magnesium (e.g., laxatives, antacids), and laxatives containing poorly absorbable elements (e.g., phosphate). Finally, osmotic diarrhea stops with fasting or avoidance of the offending substance(s).
Secretory diarrhea
Secretory diarrhea is characterized by excessive secretion of water and electrolytes by the intestine. Causes of secretory diarrhea include bacterial agents (e.g., E. coli), bile acid malabsorption (e.g., after intestinal resection), long-chain fatty acid malabsorption (e.g., steatorrhea), certain laxatives (e.g., castor oil), a hormonal disorder, and chronic alcohol ingestion. This class of diarrhea continues despite fasting.
Exudative/inflammatory diarrhea
Exudative or inflammatory diarrhea is secondary to various factors that can affect the intestinal mucosa, such as Crohn's disease, viral infections, parasites, or radiotherapy. The secretion of plasma, serum proteins, mucus, and blood by the intestine increases the mass and liquid content of stools, causing diarrhea.
Diarrhea due to accelerated transit
Diarrhea caused by accelerated transit results from a decreased contact time between digesting food and the intestinal absorption surface. The reduced contact time decreases the amount of liquids absorbed by the intestine, leading to diarrhea. Acceleration of gastric emptying can be caused by various factors, such as irritable bowel syndrome, resection of part of the intestine, and certain medications.
Nutritional approach
The nutritional treatment of diarrhea in adults aims to correct water losses and restore electrolyte balance, to identify and eliminate, if possible, the cause of diarrhea, to prevent recurrences, and to prevent and correct nutritional disorders and weight loss in cases of chronic diarrhea. Generally, hydration correction and electrolyte balance restoration are done using a rehydration solution, whose composition (water, carbohydrates, electrolytes) and administration route (e.g., oral or intravenous) depend on the individual's hydration status (e.g., mildly versus severely dehydrated). Then, dietary recommendations depend on the type of diarrhea (acute or chronic), its classification (e.g., osmotic, secretory, inflammatory), and the underlying disease causing it (e.g., Crohn's disease, irritable bowel syndrome, celiac disease, etc.). For example, for acute diarrhea occurring in the context of gastroenteritis, dietary recommendations may include:
- Starting with a fiber-restricted diet and gradually progressing to a normal diet
- Eating several small meals per day
- Paying attention to lactose consumption (secondary lactase deficiency is possible)
- Following a diet without excess concentrated sugars (e.g., polyols, fructose, sucrose)
- Consuming probiotics, especially if gastroenteritis is caused by a bacterium such as difficile, or following antibiotic treatment.
Finally, it is possible that stool frequency continues to increase during treatment and that it takes a few days before stools return to normal appearance. For chronic diarrhea, dietary recommendations are more extensive depending on the underlying disease (e.g., irritable bowel syndrome or celiac disease). Ultimately, to obtain recommendations tailored to your specific needs, do not hesitate to consult a healthcare professional who can individualize treatment for your particular case.
References
- Bouthillier, Lise. January 2019. "Digestive Tract Diseases." NUT 2047 – Clinical Nutrition 2. Montreal: University of Montreal.
- https://www.merckmanuals.com/en-ca/home/digestive-disorders/symptoms-of-digestive-disorders/diarrhea-in-adults?query=Diarrh%C3%A9e#