Eating two to three kiwis a day for at least four weeks is recommended to ease constipation.iStock
If you’re among the 15 per cent to 25 per cent of Canadians living with chronic constipation, consider adding kiwifruit and rye bread to your weekly grocery list.
According to new guidelines, consuming them is among a number of science-backed nutrition strategies that help ease constipation symptoms.
Here’s what the guidelines recommend – and don’t recommend – to treat chronic constipation.
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What is chronic constipation?
Defined as having fewer than three bowel movements a week for at least three months, chronic constipation can significantly affect an individual’s quality of life.
Common symptoms, which vary from person to person, include straining, passing hard, lumpy stools, and the sensation of incomplete evacuation. Abdominal pain, bloating and nausea can also occur.
Factors that may contribute to constipation include lack of physical activity, dehydration, changes in daily routine (e.g., travel), medication side effects and certain medical conditions such as Parkinson’s disease, diabetes and hypothyroidism.
The first evidence-based diet guidelines for chronic constipation
The new guidelines, which apply to healthy adults, were published Oct. 13 in two international journals, Neurogastroenterology & Motility and the Journal of Human Nutrition and Dietetics. They were also endorsed by the British Dietetic Association.
To develop the guidelines, researchers at King’s College London evaluated the quality and strength of evidence from 75 randomized controlled trials that investigated the effectiveness of dietary interventions for managing constipation.
The research team examined the evidence for improvement in stool frequency, stool consistency, straining, sense of incomplete evacuation, quality of life, as well as the potential for adverse side effects (e.g., bloating, flatulence).
The comprehensive review led to 59 evidence-based recommendation statements.
These new recommendations will allow health care providers to offer more personalized dietary advice to improve constipation symptoms and quality of life.
Fibre supplements
In doses above 10 g per day, fibre supplements such as psyllium are recommended to improve stool frequency and consistency and reduce the severity of straining.
To improve constipation symptoms, it’s recommended to take fibre supplements for at least four weeks.
Start with a low dose and gradually increase each week to help prevent side effects such as bloating and gas.
Kiwifruit
Eating two to three kiwis a day, green or gold, for at least four weeks is recommended to ease constipation.
Compared to psyllium, kiwifruit is more effective for increasing stool frequency.
The fibre and water in kiwifruit contribute to bulkier and softer stool, which eases its passage through the intestinal tract.
As well, compounds in kiwifruit called raphides are thought to increase the production of mucin in the gut, a building block of mucus, thereby easing constipation.
For people who experience bloating, gas and/or abdominal discomfort from fibre supplements, kiwifruit may be a preferred option.
Whole grain rye bread
Eating six to eight slices of whole grain rye bread a day for at least three weeks is recommended to increase stool frequency.
The researchers, noted, however that doing so may not be practical for some people.
Look for a dense rye bread that lists whole grain rye flour or whole rye meal as the first ingredient.
Magnesium oxide supplements
Taking 500 to 1500 mg of magnesium oxide a day for at least four weeks can increase stool frequency, improve stool consistency, as well as reduce the severity of straining and the sense of incomplete evacuation.
Magnesium pulls water into intestinal tract, softening stool and promoting a bowel movement.
Start with a daily dose of 500 mg and increase gradually with weekly increments while monitoring tolerance.
People with chronic kidney disease should consult their doctor before taking magnesium.
High mineral-content water
There’s also evidence that drinking 0.5 to 1.5 litres of high mineral-content water a day, for two to six weeks, can help relieve constipation-related symptoms.
The mineral content of waters used in studies contained, per litre, 370-573 mg of calcium, 105-1,000 mg of magnesium, 1,530-2,000 mg of sulphate and 29-1,600 mg of sodium. Milligrams per litre is equivalent to parts per million (ppm); they’re used interchangeably on mineral water labels.
Are probiotics recommended?
While some species and strains of probiotic bacteria may improve constipation, the lack of convincing evidence prevented the researchers from recommending probiotic supplements.
If you do decide to try a probiotic, do so for at least four weeks and follow the manufacturer’s instructions.
What about a high-fibre diet?
Surprisingly, the long-running advice to “increase fibre intake” may be oversimplified and outdated. The researchers found scarce evidence that doing so works for constipation.
Only one randomized controlled trial compared a high-fibre diet (25-30 g/day) to a low-fibre diet (15-20 g/day) and showed it had no impact on bowel movement frequency.
Even so, there are many other reasons to eat a high-fibre diet, including a lower risk of cardiovascular disease, Type 2 diabetes and colorectal cancer.
Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on X @LeslieBeckRD