How does constipation happen?

This uncomfortable condition is not completely understood.
This uncomfortable condition is not completely understood.

Constipation is not a rare problem. However, it is not a topic most people feel comfortable discussing.

What happens in your body to cause constipation may not be that charming to think or talk about, but knowing how the process works will clear up a lot of myths floating around regarding constipation and your bowel health. 

Here's what happens in your body from the moment you take a bite of food to the "malfunction" that leads to constipation. 

What happens after you eat? 

When you take a bite of food, you start chewing it, breaking it into smaller, more manageable pieces. Your salivary glands simultaneously release saliva to help you compact the food into a bolus, which is basically a mushy clump that can easily move down your throat.

Enzymes present in your saliva begin to digest carbohydrates in the food while you are still chewing. Your tongue then lifts to push the bolus towards your pharynx (throat), through a muscular valve called the upper oesophageal sphincter, which opens to allow the food through.

As the food enters your oesophagus, the oesophageal muscles swing into action, contracting to produce motions, called peristaltic contractionsthat push the food down towards your stomach. 

Like your oesophagus, your stomach walls are strong. They contract in order to break the food into even smaller pieces while the glands in the stomach release stomach juices to digest the proteins and fats. 

That substance then moves along to your small intestine where your body continues to extract all the nutrients it requires. Then, after your small intestine has removed every last little bit of useful material from the food, the indigestible remainder moves into your large intestine – this is where the trouble usually starts. 

Dryness is the basic cause

Dr Monique Marais, a qualified gastroenterologist and hepatologist at N1 City hospital, told Health24, "It is not that something strange happens after eating, causing constipation. There are many causes for constipation. These are mostly idiopathic, which means there is no specific cause. Some people, for example, just have slow colon transit, meaning that the movement of the colon is slow."

As your colon converts the leftover material into faeces, it absorbs water and electrolytes from the material, used by the body to avoid dehydration. A normal digestive system has food moving through your body at a normal rate which is subsequently turned into waste. While in the intestine, water is absorbed from the waste, compacting it into stool. 

In cases of constipation, the food may move too slowly, resulting in it spending too much time in the colon where too much water is absorbed. 

According to Dr Marais, "Water is important for all the physiological processes in the body, but drinking copious amounts of water won’t alleviate constipation. Our bodies manage fluid in a whole different manner to food, and the main source of fluid excretion is via our kidneys (urine), and only a small amount with stool. Only when we become dehydrated (not something that often happens), does it have an impact on our bowel motions." 

This results in dry stool which may get stuck and is hard to push out. Dryness is the basic cause of most cases of constipation.

There are, however, various other possible reasons for constipation.

"The most common causes for constipation are idiopathic; irritable bowel syndrome; and slow colon transit. Diet can play a major factor in all of these and some medications can also cause constipation. Some people with diabetes, neurological diseases or an underactive thyroid can also become constipated." 

How do laxatives and enemas work?

Drinking at least eight glasses of water daily and eating a healthy diet with fruits, vegetables and whole grain foods can help prevent constipation, but many people use laxatives as these provide quick relief from this uncomfortable condition. 

Laxatives contain chemicals that increase stool motility and frequency, thereby relieving constipation.

An enema is usually a last resort treatment option to treat constipation by introducing fluid into the intestines through the rectum. The liquid softens impacted stool, while the enema nozzle relaxes the rectum. This combination will stimulate a bowel movement.

Image credit: iStock 

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