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What is constipation?
Constipation is a condition in which bowel movements are infrequent and/or difficult to pass (1).
How common is constipation?
The estimated prevalence of constipation in North America is 12% to 19% (2).
Certain populations are at an increased risk of developing constipation, including the following (2):
- Low socioeconomic status
What are the signs and symptoms of constipation?
These are the most common signs & symptoms associated with constipation (1):
- Having fewer than 3 bowel movements per week
- Straining to have bowel movements
- Feeling like you can’t fully empty stool
- Feeling like there’s a blockage in the rectum
- Lumpy or hard stools
How is constipation diagnosed?
1. Must include 2 or more of the following symptoms for the last 3 months, with onset at least 6 months prior to diagnosis:
- Straining during more than 25% of defecations
- Lumpy or hard stools more than 25% of defecations
- Sensation of incomplete evacuation more than 25% of defecations
- Sensation of anorectal obstruction/blockage more than 25% of defecations
- Manual maneuvers to facilitate more than 25% of defecations (eg, digital evacuation, support of the pelvic floor)
- Fewer than 3 spontaneous bowel movements per week
2. Loose stools are rarely present without the use of laxatives.
3. Does not meet criteria for irritable bowel syndrome.
What causes constipation?
The following can be causes of constipation:
- Anal fissures
- Anal strictures
Connective tissue disorders
- Irritable bowel syndrome
- Ulcerative colitis
- Food allergies or sensitivities (6)
Metabolic or endocrine conditions
- Hirschsprung’s disease
- Multiple sclerosis
- Parkinson’s disease
- Spinal cord disorders
- Eating disorders
- 5-HT3 receptor antagonists (ondansetron/Zofran)
- Analgesics (opiates, tramadol, NSAIDs)
- Antacids containing aluminum or calcium
- Antiarrhythmics (amiodarone)
- Anticonvulsants (carbamazepine)
- Antidepressants (amitriptyline, MAOIs)
- Antihistamines (diphenhydramine)
- Antiparkinsonian drugs (benztropine, dopamine agonists)
- Antipsychotics (chlorpromazine, clozapine, haloperidol, risperidone)
- Antispasmodics (dicyclomine)
- Bile acid sequestrants (cholestyramine, colestipol)
- Calcium channel blockers (nifedipine, verapamil)
- Chemotherapy agents (vincristine, cyclophosphamide)
- Diuretics (furosemide)
- Oral contraceptives
5. Lifestyle factors
- Poor diet
- Sedentary lifestyle
- Ignoring the urge to poop
What medical interventions are typically used to treat constipation?
The following may be recommended by a physician:
- Bulk laxatives absorb liquid and create a soft, bulky stool.
- Examples: psyllium (Metamucil), methylcellulose (Citrucel), polycarbophil (Fibercon), and wheat dextrin (Benefiber) (10).
- Emollient laxatives soften stool by reducing surface tension and allowing fluid to mix with fecal matter.
- Examples: stool softeners such as docusate sodium (Colace).
- Lubricant laxatives coat the surface of the stool, making it easier to pass.
- Example: mineral oil (12).
- Osmotic laxatives are poorly absorbed substances that draw fluid into the intestines to soften stool.
- Examples: lactulose, sorbitol, polyethylene glycol (MiraLAX), magnesium hydroxide (Milk of Magnesia), and magnesium citrate (10).
- Stimulant laxatives increase intestinal motility (movement) and promote the secretion of fluid into the bowel.
- Examples: bisacodyl (Dulcolax), cascara sagrada, senna (Senokot), and castor oil (10).
If laxatives aren’t working, prokinetics are often used as the next treatment option (12).
Prokinetic agents stimulate the passage of stool in the intestinal tract by increasing contractions (11).
Examples include tegaserod maleate (Zelnorm) and prucalopride (Motegrity) (11).
An enema is a treatment that involves injecting liquid or gas into the rectum to “loosen up” the rectum and soften stool (11).
Does a high-fiber diet prevent and/or alleviate constipation?
Although increasing fiber intake is usually the first recommendation for relieving constipation, the evidence to support this is conflicting.
In addition, a 2012 study found that removing fiber from the diets of patients with chronic constipation actually resulted in a complete resolution of symptoms (21).
Part of the confusion comes from the fact that many studies don’t differentiate between soluble fiber and insoluble fiber, even though there is more evidence to support the use of soluble fiber for constipation (14).
More research is needed to fully understand which patients will actually benefit from added fiber and which type of fiber might be best for preventing or alleviating constipation.
What are the current recommendations for fiber?
The Adequate Intake (AI) for fiber is 14 grams per 1000 calories consumed, which translates (on average) to the numbers listed below (22):
|Life Stage Group||AI for Females (g/day)||AI for Males (g/day)|
Does the type of fiber make a difference?
- Resists fermentation by bacteria throughout the large intestines.
- Increases the water content of stool.
Types of fiber that meet these criteria include psyllium and wheat bran (23).
However, this doesn’t take into account the fact that fermentable fibers can improve the gut microbiome, which might improve constipation symptoms (26).
Below, we’ve reviewed the effects of different types of fiber on constipation.
Types of Fiber
The following is a list of fibers that have been studied specifically for their effects on bowel function in constipation.
Inulin is a soluble, fermentable fiber that belongs to a class of carbohydrates called fructans (27).
It’s unclear exactly how inulin relieves constipation, but it may be related to changes in the gut microbiome (32).
Foods that contain inulin include asparagus, chicory, garlic, Jerusalem artichokes, leeks, oats, onions, soybeans, and wheat (33).
2. Partially hydrolyzed guar gum
Guar gum is a soluble, fermentable fiber derived from the seeds of the guar plant (34).
When used as a supplement, it is typically partially hydrolyzed (broken down into smaller units), which makes the fiber easier to digest (35).
Strong evidence shows that supplementation with partially hydrolyzed guar gum (5-11 grams/day) increases stool frequency, reduces colonic transit time, and improves stool consistency in patients with constipation (18, 36, 37, 38, 39).
Partially hydrolyzed guar gum can be purchased under the name brand Sunfiber.
Psyllium is a soluble, gel-forming fiber that acts as a bulk laxative (24).
It is thought to improve constipation by supporting the growth of beneficial gut bacteria and increasing stool water content (40).
A 1998 trial actually showed that psyllium was more effective than docusate sodium, a common drug used to soften stool (43).
Psyllium can be purchased online and is also the main ingredient in Metamucil.
Pectin is a soluble, fermentable fiber found naturally in citrus peels, apples, plums, gooseberries, cherries, apricots, carrots, and quince (44).
Preliminary research suggests that pectin supplementation (24 grams/day) reduces colonic transit time, increases beneficial gut bacteria, and alleviates symptoms in patients with constipation (45, 46, 47).
More trials are needed to confirm these results.
Glucomannan is a fiber made from the root of the konjac plant, found in Asia (48).
Trials in children with constipation have found that glucomannan supplementation (2-5 g/day) moderately increases stool frequency but doesn’t increase rates of successful treatment (49).
However, a 2018 trial in pregnant women showed that glucomannan was more effective than magnesium hydroxide in the treatment of constipation (50).
It is thought that glucomannan increases stool bulk and promotes the growth of lactic acid bacteria in the colon, which may explain its beneficial effects on constipation (51).
More research is needed before this fiber supplement can be recommended for patients with constipation.
However, neither trial had a control group, so more research is needed to determine whether methylcellulose is more effective than placebo.
Methylcellulose can be purchased under the name brand Citrucel.
7. Wheat dextrin
However, there is no research to support the use of wheat dextrin in patients with constipation.
One trial actually found that stool frequency DECREASED in patients taking a daily dose of 60 grams/day (57).
Wheat dextrin can be purchased under the name brand Benefiber.
Does increasing fluid intake relieve constipation?
In one trial, increased fluid intake (1.5-2.0 liters/day) enhanced the beneficial effects of a higher fiber diet on symptoms of constipation (60).
There is also some evidence that WARM water is helpful for stimulating bowel movements, however, more research is needed (61).
Which foods may contribute to constipation?
There are no foods that universally contribute to constipation in all people.
However, some foods can be constipation-triggers for certain subsets of people:
It’s unclear exactly why this occurs, but it has been suggested that these children may have cow’s milk allergy or intolerance (62).
2. Gluten-containing foods
It is thought that alterations in intestinal motility are responsible for these effects (66).
It is a common belief that bananas contribute to constipation (67).
However, there is no research to suggest that ripe bananas contribute to constipation.
Which foods may help prevent or treat constipation?
Kiwifruit increases intestinal water retention and stool volume, which may explain its laxative effects (74).
A recent review found that prune consumption (100 grams/day) was more effective than psyllium for improving stool frequency and consistency in constipated patients (75).
Prune juice (½ cup/day) has also been found to have a laxative effect, but more research is needed (76).
The laxative effect of prunes might be explained by their high sorbitol and fiber content (77).
There is evidence that daily consumption (about 1 cup) of yogurt containing Bifidobacterium and Lactobacillus improves intestinal transit time, increases the frequency of bowel movements, and eases symptoms of constipation (78, 79)
It’s unclear whether the studies used ground or whole flaxseed.
Evidence from an animal study suggests that flaxseed works by decreasing intestinal transit time and by increasing stool weight (83).
5. Oat bran
There is some evidence to suggest that oat bran (7-8 grams/day, about 1 tablespoon dry) might improve symptoms of constipation and decrease the need for laxatives by increasing stool weight (84, 85, 86).
A 2016 trial found that fig paste (300 grams/day – this is a lot, nearly 1/2 cup!) significantly reduced colonic transit time and improved stool quality in constipated patients (87).
Evidence from an animal study suggests that fig paste might relieve constipation by increasing stool volume (88).
7. Olive oil
A 2015 trial found that olive oil consumption (1 teaspoon/day) improved symptoms of constipation as effectively as mineral oil (91).
Read our blog post on olive oil for constipation to learn more details.
8. Broccoli sprouts
Broccoli sprouts are one of the best sources of sulforaphane, a phytochemical found mainly in cruciferous vegetables (92).
A 2018 study found that constipated patients who consumed raw broccoli sprouts (20 grams/day – roughly 1/5th of a small clamshell container) for 4 weeks experienced a significant decrease in constipation symptoms compared to patients who consumed alfalfa sprouts, which contain no sulforaphane (93).
It is thought that these effects are caused by sulforaphane’s ability to protect the intestines from oxidative stress (93).
9. Rye bread
One study found that constipated patients who consumed 240 grams per day of whole grain rye bread (total 30 grams fiber) experienced increased bowel movement frequency and shortened transit time when compared with patients consuming white bread (94).
However, this is a lot of bread to consume in one day for most people (4 to 5 slices of this very dense rye bread).
More research is needed to determine if smaller doses of rye bread are equally effective.
However, clinical trials are needed to confirm these results.
11. Citrus fruits
Naringenin is a natural flavonoid found in citrus fruits (98).
However, research in humans is needed.
Preliminary animal research suggests that apple fiber might increase intestinal motility and prevent constipation (100).
However, research in humans is needed.
13. Wheat bran
More research is needed to determine whether wheat bran is effective for patients with constipation.
14. Sweet potatoes
Evidence from a recent trial suggests that consumption of boiled sweet potato (200 grams/day, about ⅔ cup mashed) was effective for the prevention of constipation in hospitalized patients (103).
However, these patients were also treated with a warm footbath and abdominal massage, so it’s unclear which treatment actually produced the results.
15. Sugar alcohols
Sugar alcohols (polyols) are a group of poorly absorbed carbohydrates that are often used as artificial sweeteners (104).
Sorbitol, a type of sugar alcohol, has been used as a laxative in patients with constipation (105).
Although no studies have evaluated the effects of sorbitol-containing foods on constipation, there is evidence that sorbitol may promote bowel movements by acting as an osmotic laxative (104).
Foods that naturally contain sorbitol include apples, apricots, dates, figs, nectarines, peaches, pears, plums, prunes, and raisins (106).
Are any supplements recommended?
Senna is a common laxative made from the dried leaves and pods of a shrub called Cassia senna (107).
Its laxative effect is thought to be caused by substances called sennosides, which are metabolized by bacteria in the intestines to promote water secretion and motility (107).
A 2006 trial found that consumption of senna-based herbal tea (1 cup/day) significantly increased the number of bowel movements in nursing home residents with constipation (108).
Smooth Move is a popular tea that contains 1080 mg senna leaf. (Note that the effects can be drastic, causing urgent bowel movements.)
A recent trial found that magnesium oxide supplements (500 mg, 3 times/day) for 28 days significantly improved the rate of spontaneous bowel movements in patients with constipation (109).
These supplements are considered osmotic laxatives, because they are poorly absorbed and draw water into the intestines (110).
Other forms, such as magnesium citrate and magnesium sulfate, are also commonly used as laxatives (111).
A recent review found that supplementation with Bifidobacterium or Lactobacillus increased stool frequency by 0.8 bowel movements per week and reduced intestinal transit time by 15 hours in constipated adults (114).
However, more research is needed to determine the effects of specific strains and doses (115).
Triphala is an Ayurvedic herbal blend consisting of Terminalia chebula (Haritaki), Terminalia bellerica (Bibhitaki), and Phyllantus emblica (Indian gooseberry) (116).
In one study, patients with constipation who were treated with a supplement containing Triphala experienced significant improvements in bowel movement frequency and other symptoms (117).
More, higher-quality research is needed.
5. Aloe vera?
Barbaloin, one of the major components of aloe vera, plays a role as a laxative by enhancing motility and stimulating mucus secretion in the colon (118).
There is also concern that, when ingested, aloe vera whole leaf extract may have cancer-promoting effects, based on evidence from one animal study (122).
6. Cascara sagrada?
Cascara sagrada consists of the dried bark of the trunk of branches of Rhamnus purshiana, a shrub found in North America (107).
It was used for centuries by Native Americans as a laxative, and was a common ingredient in laxative drugs until 2002, when the FDA banned it due to a lack of research to prove its safety and efficacy (123).
Although Cascara sagrada is still available as an herbal supplement, there are no recent studies examining its effects on constipation.
Are there any lifestyle recommendations for constipation?
1. Exercise regularly
Exercise is commonly recommended for the management of constipation, based on the idea that it shortens intestinal transit time (124).
A recent review found that exercise (including walking) significantly improved symptoms of constipation (125).
However, the authors also noted that the studies were poorly designed and had a high risk of bias, so it is difficult to make definitive recommendations (125).
2. Use a Squatty Potty
The Squatty Potty is a toilet stool that raises the knees above the hips to allow for a natural, squatting position.
Squatting straightens the rectoanal canal, which reduces the need to push or strain in order to have a bowel movement (126).
3. Try abdominal massage
Clinical trials have shown that abdominal massage stimulates peristalsis and decreases colonic transit time, which significantly increases bowel movements and improves quality of life in patients with constipation (129, 130, 131).
These massages are typically performed 3 times each day before meals, for 15 minutes each (132).
Generally speaking, they involve a combination of stroking, circular movements with the palm of the hand, kneading, and vibration (132).
The strokes are applied along the large intestine, in the direction of stool movement.
Amy is a registered dietitian nutritionist and certified LEAP therapist. She received her Masters in Nutrition Diagnostics from Cox College and her Bachelors in Dietetics from Missouri State University. Her passion is finding ways to communicate nutrition research in an interesting and easy-to-understand way.