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food for thought

Psyllium husk is especially effective in combating constipation.Yuliya Padina/iStockPhoto / Getty Images

If you’re among the one in four Canadians who suffers from constipation, you likely know too well that the condition can make you feel miserable – bloated, gassy, lethargic and irritable.

For some people constipation lasts only a short time, but for others it can go on for weeks and months.

Recommendations to treat constipation emphasize increasing fibre intake, in particular by using a fibre supplement. But guidelines on the type, dose and duration of fibre supplementation haven’t been clear.

Now, an updated review of studies – the largest review to date – provides evidence for optimal fibre supplementation guidelines to improve chronic constipation.

What is chronic constipation?

Not having a daily bowel movement doesn’t mean you’re constipated. Medically speaking, constipation is defined as having less than three bowel movements a week.

Chronic constipation occurs when you have infrequent bowel movements – whether hard, formed or small stools – or difficulty passing stools for several weeks or longer. The condition interferes with quality of life, affecting work and social relationships and mental well-being.

Research suggests that for half of people with chronic constipation, recommendations to increase fibre, or to use laxatives, are ineffective or associated with uncomfortable side effects such as bloating and gas.

Psyllium husk, also called isabgol, is fiber derived from the seeds of the Plantago ovata plant found in India.iStockPhoto / Getty Images

The latest research

The aim of the current research was to identify the optimal type of fibre supplement, dose and duration of treatment for the management of chronic constipation. The analysis, published in the October issue of the American Journal of Clinical Nutrition, included 16 randomized controlled trials involving 1,251 adult participants.

The researchers assessed the effect of fibre supplements on frequency of bowel movements, bowel transit time (i.e., how long it takes food to move through the gut), as well as symptoms such as bloating, gas, abdominal pain and straining severity.

The studies used various types of fibre supplements, including psyllium powder, polydextrose powder, inulin, guar gum, pectin powder and wheat bran. Doses ranged from four to 40 g per day and treatment durations lasted two to eight weeks.

Overall, fibre supplementation was effective at providing constipation relief. The results showed that psyllium was the most effective, increasing bowel movement frequency by three per week, improving stool consistency and lessening severity of straining.

When it came to supplement dose and duration, fibre doses greater than 10 g per day and treatment of at least four weeks were found to be optimal for managing constipation.

The study also found that fibre supplements worsened flatulence, especially inulin-containing supplements. Inulin, a prebiotic fibre derived from chicory root, is fermented by gut bacteria; consuming high doses can cause gas and bloating.

Fibre supplement considerations

Before starting a fibre supplement, review your medications with your pharmacist. Fibre supplements can decrease the absorption of certain medications, including ones used to treat thyroid disorders, depression and Type 2 diabetes.

Start slowly to prevent digestive discomfort. Begin with the lowest recommended dose and gradually increase the amount of fibre.

Take a fibre supplement with at least 250 ml of water to enhance effectiveness and prevent side effects. Be consistent; take your fibre supplement daily.

Psyllium husk is a soluble fibre, which dissolves in water and forms a gel-like material during digestion.Peter Blottman Photography/iStockPhoto / Getty Images

Don’t overlook dietary fibre

Try to get most of your daily fibre from whole foods, which contain various types of fibre (many fibre supplements provide only one type) along with nutrients and protective phytochemicals.

Besides promoting digestive health, a high-fibre diet is linked to a lower risk of Type 2 diabetes, cardiovascular disease and certain cancers.

Daily fibre recommendations for adults, ages 19 to 50, are 38 g (males) and 25 g (females). Men and women over 50 require 30 and 21 g per day, respectively.

Whole grains, fruits, vegetables, pulses, nuts and seeds contain two types of fibre in varying amounts: soluble and insoluble fibre.

Soluble fibre dissolves in water and forms a gel-like material during digestion. It helps to lower blood sugar and blood cholesterol levels. Good sources include oats, oat bran, psyllium husks, barley, beans and lentils, citrus fruit, pears, apples and chia seeds.

Insoluble fibre remains largely intact as it passes through the digestive tract. This type of fibre adds bulk to stool, promoting regularity. Wheat bran, whole wheat pasta, whole grain rye bread, pinto beans, nuts, sweet potatoes, kale, green peas and raspberries are examples of foods high in insoluble fibre.

Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on Twitter @LeslieBeckRD