Certain types of fiber may be more effective than others in alleviating constipation and improving stool consistency, new research shows.
The meta-analysis, published in the American Journal of Clinical Nutrition in July, found that psyllium fiber, specifically, was most effective in providing relief from chronic constipation—namely in increasing stool frequency and decreasing straining. This led researchers to suggest psyllium as a first-line strategy for treating chronic constipation.
Pectin, another type of fiber, may also provide chronic constipation relief, but researchers warn that data for this type of fiber wasn't quite robust enough to say for sure.
“The main takeaway from this study is that not all fiber is created equal,” Sean Spencer, MD, PhD, a gastroenterologist who specializes in neurogastroenterology and motility at Stanford University, told Health. “Some fibers are more effective overall and some fibers improve specific aspects of constipation, such as straining or stool frequency, more than others.”
Chronic constipation—or fewer than three bowel movements a week, for more than six months— impacts an estimated 12% of the global population. But, without more standardized recommendations on how to relieve chronic constipation, many patients are left to experiment with relief techniques—often resulting in disappointment.
According to researchers, this new review can hopefully provide healthcare providers with more information "to provide standardized and effective recommendations to patients with chronic constipation."
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Psyllium Fiber Shows Greatest Relief for Chronic Constipation
For this meta-analysis, researchers from King's College London, looked at 16 randomized controlled trials on fiber supplementation in individuals with chronic constipation.
The studies looked at various types of fiber supplementation, including psyllium, pectin, inulin, and wheat bran. The most effective fiber supplementation, according to researchers, was seen by psyllium supplements and fiber doses of a minimum of 10 grams per day—which amounts to about two tablespoons.
Patients who took psyllium supplements experienced approximately three more bowel movements a week—slightly more than those who took laxatives alone, which was linked to 2.5 more bowel movements a week. Pectin similarly increased stool frequency; however, there was less data overall on this type of fiber.
Psyllium supplements also significantly improved stool consistency, as did inulin-type fructans. The higher fiber dose of more than 10 grams per day also greatly improved stool consistency, as gauged by the Bristol Stool Form Scale.
The duration of fiber supplementation mattered too—researchers found that treatment duration periods more than four weeks impacted stool frequency and decreased gut transit time, or the time it takes food to move through the gastrointestinal tract.
The researchers say the findings suggest that psyllium could be a first-line treatment for people with chronic constipation who specifically experience infrequent bowel movements, hard stools and straining. It may not, however, be the most effective treatment for people experiencing other symptoms such as bloating or incomplete defecation.
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The type of fiber supplementation researchers are recommending here—psyllium—is the kind primarily used in fiber supplements, like Metamucil, according to Tamara Randall, MS, RDN, an instructor in the Department of Nutrition at Case Western Reserve University School of Medicine.
Psyllium is made from the husks of the seeds of the plantago ovata plant, commonly found in India. Many studies have shown that this form of fiber—when combined with water—can thicken up stool and help it pass through the gut more easily.
The other most useful supplement—pectin—is more widely found in the fruits and vegetables we eat on a regular basis (think: apples, carrots, oranges, grapefruits and lemons). Research has demonstrated that people taking pectin supplementation spent, on average, less time on the toilet and experienced more frequent bowel movements.
Fiber can improve overall health by promoting a healthy gut microbiome and relieving constipation.. "This is low-hanging fruit for many people—a simple addition to their diets that can have a big improvement on health and make them feel better," Dr. Spencer said. Most patients with chronic constipation are first advised to increase fiber intake.
It's important to gradually increase the amount of fiber you consume. "Both your GI tract and your microbiome can adapt to fiber intake, but this takes time, often several weeks," Dr. Spencer said, adding that when it comes to fiber the key is to start low and go slow. You'll also want to drink enough water with the fiber to help the stool form comfortably.
Though fiber is a generally safe intervention, consuming too much can cause gas, bloating and discomfort, according to Randall.
It's worth noting, too, that each person will likely need a slightly different amount of fiber. Depending on their gut health, some people may need more than 10 grams a day and others may require less.
The frequency, quality and quantity of bowel movements is very individual. "Chronic constipation is hard to define, it's different for every person, and that's why there isn't going to be one answer," Randall said.
Ultimately, any fiber is better than no fiber. Even though this new research demonstrates that psyllium had the greatest effect for people with chronic constipation, this does not mean everyone needs to go out and buy the supplement.
"A grand majority of people who have some degree of constipation will find relief by increasing any type of fiber in their diet," said Randall, who added that the easiest way to increase your fiber intake overall is to eat more fruits and veggies.
However, if you try adding fiber to your diet under the supervision of a healthcare professional and your condition does not improve, there are likely other causes of constipation that need to be identified and treated.
"If patients are not responding to fiber therapy," said Dr. Spencer, "we suggest they be evaluated by their doctor to better understand the cause of their constipation."