Digestion is the process by which food is broken down into simpler substances so that it can be absorbed by the alimentary tract. It is both a mechanical and chemical process that starts from the time food enters the mouth. Problems with digestion (maldigestion) may arise in any part of the alimentary tract. A disruption in one part of the tract will inadvertently affect digestion and absorption in neighboring sections thereby eliciting a wide range of signs and symptoms.

Maldigestion vs Indigestion

Maldigestion should not be confused with indigestion. The latter is also known as dyspepsia and encompasses a number of gastrointestinal symptoms that are referred to as indigestion or an upset stomach. Indigestion does not mean that the process of digestion is impaired, although patients with maldigestion and malabsorption syndromes may experience mild to severe indigestion.

Signs and Symptoms of Digestion Problems

The digestive process is a complex and well coordinated sequence of events. It is designed to yield maximum nutrition from food for subsequent absorption. Digestion problems, or maldigestion, will disrupt absorption and it is often the signs and symptoms of malabsorption that raises the concern about an impediment within the alimentary tract.

The gastrointestinal signs and symptoms include :

Other conditions and symptoms that may arise from digestion problems include :

Malabsorption as a result of maldigestion is often evident in the stool resulting in signs like steatorrhea (fats in the stool).

Causes of Digestion Problems

Mechanical Digestion Problems

Disorders affecting mastication (chewing), as well as stomach and small intestine motility, impairs mechanical digestion. Gastrointestinal motility does not only affect the movement of food through the gut, it is also play a major role in mechanical digestion. When mechanical digestion is affected, food in the stomach and small intestine may not be adequately exposed to the digestive enzymes. Therefore mechanical digestion can upset chemical digestion.

Some of the more common causes of mechanical digestion problems include :

  • Poor dentition
    • Broken or missing teeth, as well as trismus or TMJ (temporomanibular joint) dysfunction, usually does not cause any major problems in terms of maldigestion as the other parts of the gut will complete the digestive process.
  • Gastric and ileal resection or bypass
    • Surgical removal or alteration of the upper gastrointestinal tract may be done in cases of cancer or for medical weight loss. This hampers mechanical digestion.
  • Gastrointestinal obstruction
    • Tumors, strictures and pseudo-obstruction are some of the causes of an obstruction. This is discussed further under blocked bowel (small intestine) and blocked colon (large intestine).
    • An obstruction even in the distal parts of the alimentary gastrointestinal tract, like the colon, will cause food and chyme to back up in the gut and this affects digestion even in the more proximal areas, like the stomach and small intestine.
  • Slow or Rapid Transit
    • Rapid transit means that food moves too quickly through the gastrointestinal tract and the digestive process (both mechanical and chemical) are unable to have the appropriate effect on food. It is often associated with diarrhea.
    • Muscular disorders of the muscles lining the gut or neurological problems that affect peristalsis will result in slow transit time and impair digestion. This is often associated with constipation.
  • Irritable bowel syndrome
    • The exact cause of IBS is still unknown but this functional bowel disorder seems to be related to transit time. It results in diarrhea-predominant IBS or constipation-predominant IBS.

Chemical Digestion Problems

Most of the common causes of maldigestion are conditions that impair chemical digestion.

  • Enzyme Deficiency
    • The list of catalysts that are responsible for chemical digestion as well as the organs that secrete it are discussed further under Digestive Enzymes.
    • Low volumes of stomach acid or a lack of stomach acid is known as hypochlorhyria or achlorhydria respectively. The causes are discussed under Achlorhydria.
    • Pancreatic exocrine insufficiency is when the production and secretion of digestive enzymes from the pancreas is disrupted. This is discussed further under Pancreatic Enzyme Deficiency.
    • At times, sufficient amounts of digestive enzymes may be secreted but fail to activate within the lumen. This is seen in conditions like Zollinger-Ellison syndrome where the excess secretion of gastric acid affects the activation of pancreatic enzymes due to a low pH within the lumen of the duodenum.
    • Inflammation of the bowel like in Crohn’s disease and celiac disease may affect the enzyme secretion from the bowel wall. Other disorders of the bowel wall may have a similar effect.
    • Deficiencies of a single enzyme or certain enzymes without impairment of the gland responsible for its secretion  may arise due to a genetic deficiency like in primary lactose intolerance (lactase deficiency) or secondary to other diseases like in fructose malabsorption.
    • High or low quantities of digestive hormones or a lack of these hormones may also affect digestion as these compounds regulate the digestive process.
  • Bile Deficiency
    • Bile emulsifies fats in the gut so that other fat-digesting enzymes like pancreatic lipase can act more efficiently.
    • A deficiency may be related to low bile production or more frequently low or no bile secretion.
    • Obstruction of the bile ducts impairs bile secretion, while liver and gallbladder disorders can affect bile production and storage respectively.
    • Gallstones are the most common cause but a list of other possible causes are discussed under cholestatic jaundice.

References

  1. Malabsorption. Emedicine

Article reviewed by Dr. Greg. Last updated on October 18, 2010