Functional constipation in adults

What is constipation?

Constipation is a common gut problem, with reports that as high as 25 % of the world’s population suffer from this persistent, and often socially restrictive, condition. Although certain population groups suffer more than others, constipation is a symptom that everyone may experience in their lifetime – from young children to the elderly. And it is not only physically uncomfortable but can greatly reduce the sufferer’s quality of life and psychological well-being.

You may suffer from constipation if you experience two or more of the following:

  • Less than 3 bowel movements per week
  • For more than 25 % of the evacuations:
  • Lumpy or hard stools
  • Feeling of incomplete evacuation
  • Feeling of obstruction/blockage
  • Straining
  • Manual evacuation manoeuvres required


It should be noted that although constipation is often self-treated, any acute or sudden changes to
bowel movements always requires medical investigation.

The different types of constipation

There are two types of constipation: primary and secondary.

Secondary constipation is due to factors, such as medication, neurological disease or physical intestinal disorders.

Primary constipation includes functional constipation, the most common type of constipation, which is present when no underlying medical disease can be found.

Causes of functional constipation:

There are many causes of functional constipation, including:

  • Lack of exercise or reduced mobility
  • Dehydration or lack of adequate hydration
  • Not enough fiber in the diet
  • Food intolerances
  • Changes in habits or lifestyle, – travel, pregnancy, old age
  • Gut microbiota dysbiosis, an imbalance in our gut bacteria
  • Disturbances in the nervous system communication between the gut and the brain
  • Impaired gastrointestinal motility, movement and transit of contents
  • Disturbed gut transit time.


What does gut transit time mean?

The time it takes for the food contents to travel though the digestive tract is called the transit time. One of the main functions of the large intestine is to reabsorb water from the food waste to form the stool. If the transit time is slow, the stool will spend a longer time in the large intestine and become harder, drier and more difficult to evacuate.

Transit time is affected by numerous factors including:

– Our gut microbiota composition and balance
– Methane production by specific gut bacteria (methane production slows transit time)
– Low digestive muscle tone or low sensitivity to nervous system stimulation
– Lack of fiber (adequate fiber normalizes transit time)
– Delayed stomach emptying

Who is at risk of functional constipation?

Anyone can suffer from constipation; however, the prevalence is higher in women, the elderly and those living in low socioeconomic situations. It is also a very common symptom in pregnancy, due to hormonal changes affecting the time it takes for the stool to pass through the intestinal tract, the transit time.

The role of gut bacteria in constipation

The bacteria in the gut, our gut microbiota, play many crucial roles in the health of the digestive system. The gut bacteria produce substances, called lactate and short chain fatty acids, that change the pH (acid level) of the intestine. This can increase peristalsis (wave-like muscular contractions that move food through the intestines), reduce transit time and improve stool frequency. Dysbiosis, which is an imbalanced gut microbiota, contributes to constipation.

Individuals with constipation often have significantly different gut bacteria composition than nonconstipated healthy people, with higher levels of methane producing bacteria in their intestines, which slows intestinal transit time. A balanced microbiota can reduce methane production, alter gut function, improve stool consistency and frequency, and help with constipation symptoms, including bloating, abdominal discomfort and pain.