Digestion is just one process that is necessary for humans to acquire nutrients from food. Without digestion, survival would not be possible. However, as with any part and process of the body, a host of different problems can arise. This means that digestion can be upset to in different ways and to varying degrees. Milder digestion problems may not pose a significant risk to health but affect the consumption of certain foods. Severe digestion problems can lead to deficiencies and disturbances which over time can be life threatening.
What is maldigestion?
Maldigestion is the term used to describe a disturbance in the digestive processes. When food is consumed, it has to be digested mechanically and chemically. This ensures that food is boken down into smaller particles and simpler substances which can then be absorbed. These absorbed nutrients are then processed further by the body and utilized for energy production, building and repairing organs and tissues and other life-sustaining processes.
One of the common examples of maldigestion is lactose intolerance. The enzyme lactase which is needed for digesting the milk sugar lactose is deficient. Normally lactase is produced by the cells of the small intstine. As a result of the lack of this digestive enzyme, lactose in dairy remains undigested. Therefore people with lactose intolerance avoid dairy so thats symptoms like nausea, bloating, abdominal cramps and diarrhea do not arise.
Read more on lactose intolerance.
Where does digestion occur?
Digestion starts the moment food is placed in the mouth and continues throughout the gut. It is both a mechanical and chemical process. Chewing food in the mouth and churning food by strong stomach contractions are examples of mechanical digestion where food is broken to smaller particles. Digestive enzymes in saliva, stomach secretions and pancreatic juices are responsible for chemical digestion where food is broken down into simpler substances.
Causes of Maldigestion
Some of the conditions that can cause maldigestion have been discussed below. One condition that can affect digestion, and specifically the enzymes responsible for chemical digestion, is a genetic defect. In these cases the enzymes are not produced or the structure of the enzyme is not ideal for it to perform its required function. These genetic defects can therefore lead to digestive enzyme deficiency.
Chewing is the first stage in mechanical digestion and requires healthy teeth, bones, muscles and nerves that control it. If these structures are not working properly, food cannot be broken down sufficiently. Similarly saliva contains enzymes like ptyalin that starts chemical digestion. A lack of saliva may therefore impede digestion although enzymes further down the digestive tract usually compensates.
- Broken teeth
- Broken jaw
- Bell’s palsy
The stomach produces powerful digestive enzymes and the muscles within the stomach wall churns and crushes food. Problems with the stomach can affect digestive enyme secretion as well as gastric acid. Any weakening or paralysis of the stomach muscles can impaire mechanical digestion in the stomach and may also impair the control of partially digested food out of the stomach.
- H.pylori infection
- Autoimmune gastritis
- Diabetes mellitus
- Stomach surgery
The pancreas empties its digestive enzymes into the small intestine. It produces powerful digestive enzymes that can act on all types of food to break it down into simpler substances for absorption. These digestive enzymes are activated once it leaves the pancreas and acts upon food in the small intestine. A number of different problems can prematurely activate these enzyme, hamper its production or block its outflow.
- Pancreatic cancer
- Pancreas surgery
- Cystic fibrosis
- Shwachman-Diamond syndrome
Gallbladder and Liver
The gallbladder stores bile produced by the liver. Bile emulsifies fats. This means that it breaks fats into smaller particles so that fat-breakinge enzymes, like lipase, can then digest it. Without bile, not all the fat in foods will be digested and absorbed. As a result these fats will pass out with the stool. Sometimes the problem is not with the gallbladder or adjoing ducts but with the liver and its production of bile.
- Liver and gallbladder cancer
- Bile duct strictures
The small intestine is the longest part of the digestive tract. Most digestion and absorption of nutrients occur within the small intestine. As with the upper parts of the digestive tract, the small intestine also secretes digestive enzymes from specialized cells in its wall that produces these enzymes. This is in addition to the chemical digestion that has already been initiated by digestive enzymes from the stomach and pancreas.The contractions of the small intestine wall also helps with mechenical digestion by squashing and pushing food along its course.
- Enteritis (infectious and non-infectious)
- Crohn’s disease
- Celiac disease
- Paralytic ileus
- Diabetic neuropathy
Bowel Transit Time
For digestion to be optimal, food and fluids need to move through the digestive tract with sufficient time for digestive enzymes to act. If this bowel transit is too rapid then the enzymes may not be able to properly break down nutrients whch then cannot be absorbed. Various diseases may affect bowel transit time, like many diarrheal illnesses. However, it can also occur when there is no disease of the digestive tract.
Irritable bowel syndrome (IBS) is one condition where bowel transit time is affected. In IBS-D (irritable bowel syndrome with diarrhea), bowel transit time is rapid and this can affect digestion. However, IBS is not a disease. Rather it is a disturbance in the normal functioning of the bowel. Hence irritable bowel syndrome is known as a functional bowel disorder.
Read more on irritable bowel syndrome.
Signs and Symptoms
A problem with digestion in one part of the body may not necessarily affect overall digestion of nutrients. There are other digestive enzymes from different parts of the gut that can compensate for a problem with digestion in just one area. However, when this is not sufficient and nutrients are not digested and absorbed then it may give rise to some of the following signs and symptoms:
- Nausea, and sometime vomiting
- Abdominal cramps or pain
- Excessive gas, especially flatulence
- Steatorrhea (fat stool)
Depending on the type and severity of digestive problem, nutritional deficiencies can arise. This in turn can cause other complications which may present with various other signs and symptoms.