By Mind Your Body, The Straits Times, Friday, email@example.com, Jul 04, 2014
Fibre is resistant to digestion. If patients with slow intestinal transit are given fibre, it will only accumulate in the intestine and give rise to bloating.
SINGAPORE - One in four people here suffer from chronic constipation.
They may strain to pass stool, feel as though there is something blocking the flow and feel that they have not completely emptied their bowels after.
It is a problem that gets worse with age, so with the greying population, doctors here say that the incidence of chronic constipation is set to rise.
Elsewhere in Asia, self-reported surveys show about 13 to 17 per cent of the population is plagued with the condition, which is likely to be underestimated.
But Asian patients are often given inappropriate dietary advice and under-treated for constipation, said Dr Gwee Kok Ann, president of the Asian Neurogastroenterology and Motility Association.
The gastroenterologist at Gleneagles Hospital led a 20-man task force to draw up guidelines for the management of chronic constipation in Asia. The guidelines - which took a year in the making - were drawn up by 20 gastroenterologists and published in the Journal Of Neurogastroenterology Motility in April last year.
One of the biggest misconceptions is that chronic constipation can be solved by eating more fibre. But Dr Gwee's guidelines caution against more fibre intake if patients are eating enough in the first place.
Constipation can be caused by lifestyle habits, medical conditions such as hypothyroidism, side effect of medication such as opiates, hormonal changes during menstruation and pregnancy and physiological impairments in the colon or pelvic floor muscles.
Increased dietary fibre intake has traditionally been one of the first-line remedies for constipation. But the guidelines recommend that doctors ask about patients' fibre intake and prescribe bulk-forming laxatives or advise more fibre intake only if patients are deficient in fibre.
This can be achieved by consuming two servings each of fruit and vegetables (these give a total of 10 to 12g of fibre) and five to seven servings of wholegrain products, such as brown rice and wholemeal bread, and alternatives like white bread and white rice (10 to 14g of fibre), said Ms Gladis Lin, dietitian at the HPB's Centre of Excellence for Nutrition.
Dr Gwee said research has shown that patients with constipation do not eat any less fibre than healthy people, so a lack of fibre is not always the cause of the problem.
Dr Gwee also pointed out that there is "really no good data" to show that patients with severe chronic constipation lack fibre in their diet. In fact, many are observed to suffer more discomfort when placed on a high-fibre diet.
A common type of constipation arises from the slow or weak movements in the intestines.
Dr Gwee explained that fibre is resistant to digestion. If patients with slow intestinal transit are given fibre, it will only accumulate in the intestine and give rise to bloating.
This is because fibre soaks up water and expands in the gut to make a person feel bloated.
They create bulky stools, which, along with gas produced during the fermentation of fibre, leads to flatulence and cramping from the intestines being stretched, he added.
Some doctors recognise this and no longer routinely advise greater fibre intake.
Dr Francis Seow-Choen, consultant surgeon at Novena Colorectal Centre, asked a 23-year-old woman patient who had been constipated for a year to cut back on her fibre intake early this year.
From eating a full plate of greens daily, the administrative assistant now eats only a ladle-sized portion.
She says her stool is now smaller and softer and she goes to the toilet every four to five days, instead of once weekly. An increase in fibre can also lead to a complication called faecal impaction, in which stool accumulates and remains stuck in the rectum.
Dr Ong Wai Choung, a consultant at the department of gastroenterology and hepatology at Singapore General Hospital (SGH), said such extreme cases of constipation are seen at the hospital's emergency department, where the patients are given laxatives or have the stool manually prised out.
Though not fatal, impaction causes patients severe distress as "they feel as though they are in labour".
Faecal impaction is most likely to occur among patients who are elderly, mentally ill, neurologically impaired, terminally ill or living in institutions like nursing homes, said Dr Robert Lo, a consultant at the department of gastroenterology and hepatology at Tan Tock Seng Hospital.
These patients are physically inactive, may not eat well and often take medication which causes constipation.
In fact, six or seven out of every 10 elderly patients will have constipation, said Dr Lawrence Tan, a consultant at the department of geriatric medicine at Khoo Teck Puat Hospital.
A last resort for those with slow-transit constipation is a colectomy, the removal of part or all of the colon.
But the guidelines will recommend a psychiatric assessment of the patient, in addition to other tests, before the drastic procedure is done.
At SGH, fewer than five are done on severely constipated patients each year. It has fallen out of favour with most doctors because of dismal outcome, said Dr Mark Wong, consultant at its department of colorectal surgery.
Hence, if fibre increase is not a suitable treatment, laxatives should be used or patients should undergo pelvic-floor exercises to train uncoordinated muscles.
As for laxatives, Dr Gwee said doctors and patients alike have the misconception that people can get too dependent on them to be weaned easily.
It is why patients are frequently prescribed short courses of laxatives and, sometimes, told to avoid using them daily.
On the contrary, some research shows a drug like prucalopride can have benefits even when used for up to 24 months.
The guidelines also recommend that patients who are being considered for surgery to remove part or all of the colon (colectomy) in order to speed up digestion should undergo a formal psychiatric evaluation, in addition to other tests.
A study from the United States found that patients with constipation who had a history of sexual abuse had a 10-fold increased risk of surgery and yet significantly poorer outcome after a colectomy.
Although it is not known why, Dr Gwee said it is likely that the loss of self-esteem caused patients to develop problems with their bodily functions.
But a review of Asian publications showed that psychiatric evaluation is, disturbingly, rarely done.
Guidelines on the right track
Doctors in the primary care setting, and public and private hospitals agree that these guidelines are on the right track.
Dr Wang Yu Tien, a consultant at the department of gastroenterology and hepatology at Singapore General Hospital, said since November 2009, doctors at the hospital advise patients with chronic constipation who do not respond to conventional treatment to be screened for psychological disorders.
Dr Francis Seow-Choen, medical director of Fortis Surgical Hospital in Adam Road, cautioned that a psychiatric assessment should not be the basis of whether a surgery is needed or not. "Ultimately, it is still the surgeon making the final decision as to whether he thinks that surgery may or may not help the patient," he said.
For years, Dr Seow has firmly believed that fibre is the "main cause of constipation and that removing it improves constipation".
He has observed that very few of his patients required long-term laxatives if they are willing to stop or decrease their fibre intake.
This is an excerpt of an article first published on Feb 6, 2014.