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Constipation

Fiber and Relief of Constipation

Author:

Elaine M. Hinzey, RD, LDN

Reviewed and Updated by Anne Danahy, MS, RD, LDN

 

One Recommendation May Not Fit All

Chronic constipation is defined as infrequent bowel movements (less than 3 per week), or feces that are hard or painful to expel, or a sensation of incomplete evacuation. It is a common health problem that affects an average 15% of the North American population (Schiller, 2004). A higher fiber diet and increased fluid intake are often recommended as a first line defense to treat constipation. In most cases, it is effective, but there are some patients who may not benefit from this recommendation.

Types of Constipation

Constipation may have many causes, but generally, there are three main types of primary or idiopathic constipation:

  • Functional – mainly presents with pain and discomfort and includes constipation related to irritable bowel syndrome
  • Slow transit – common symptoms include prolonged time between bowel movements, bloating, abdominal distension, and discomfort
  • Outlet dysfunction – caused by mechanical dysfunction such as stricture, pelvic floor dysfunction, cancer, anal stricture, Hirschsprung disease (lack of nerve cells in the colon)
  • Some patients may have combined forms of primary constipation

Secondary constipation is caused by:

  • Lifestyle
  • Medical conditions such as diabetes, hypothyroidism, Parkinson’s disease, and multiple sclerosis
  • Pregnancy
  • Advanced Age
  • Certain medications, especially calcium channel blockers, beta blockers, opioids, diuretics, antidepressants, anticonvulsants, anti-acids, anticholinergics, and antispasmodics
  • Calcium and iron supplements
  • Recently, some people have hypothesized that low-energy intake and food sensitivities can cause chronic constipation (Schiller, 2004)

 

Studies on Fiber and Constipation

The basis for recommending fiber to people struggling with constipation dates to epidemiological observations in the 1960s, however, evidence that increasing dietary fiber will alleviate constipation is somewhat mixed. Although many more high-fiber foods have become available in the past several decades, documentation of improved constipation prevalence does not exist. In normal, healthy people, fiber intake can undoubtedly drive stool output. However, evidence is mixed in people who have chronic constipation.

  • In a meta-analysis of 5 studies which reviewed the role of fiber on constipation, researchers determined that while it does increase stool frequency, it does not improve stool consistency, treatment success, laxative use, or painful defecation (Yang, et al., 2012).
  • In a systematic review published in Alimentary Pharmacology and Therapeutics in 2011, research showed that soluble fiber may benefit chronic idiopathic constipation, but the data for insoluble fiber were conflicting. All four studies that used soluble fiber (three of which used psyllium) resulted in significant improvement of symptoms and increased stool output. One of the two trials that looked at insoluble fiber showed a significant difference in mean number of stools per day and improved symptoms of constipation, while the other study found no significant difference in response to therapy. More data were deemed necessary before determining the true efficacy of either type of fiber (Suares, et al., 2011).
  • Researchers conducted a randomized controlled study which examined the effects of a vegetable fiber on individuals in their twenties, with chronic constipation. Their results showed that consuming a fiber-rich vegetable powder made from chicory, broccoli, and whole grains, improved bowel movements at both 2 and 4-weeks, compared to the control group. The vegetable fiber treatment provided 17 g of fiber each day. Stool hardness, amount of stool, sensation of incomplete evacuation, and straining to defecate were all improved (Woo, et al, 2015)

 

Fiber Recommendations

Many patients may respond to fiber supplementation, so they should try this approach before undergoing other therapies. Supplementation most likely helps patients with most types of functional constipation, especially those who might find help by improving stool consistency. However, it is reported that fewer than 30% of those who suffer from slow transit constipation or pelvic floor dysfunction see improvement from fiber supplementation. In some cases, adding more fiber can worsen their symptoms (Foxx-Orenstein, et al., 2008).

When recommending a higher fiber diet for patients, advise them to increase fiber from natural foods to 20 g/day over a period of 2-3 weeks. Encourage increased water or fluid consumption along with fiber. If constipation-related symptoms are not improved after this time, the addition of a fiber supplement such as psyllium is recommended. If symptoms persisted despite both the dietary changes and the addition of the supplement, the health-care provider should consider further testing (Foxx-Orenstein, et al., 2008).

Fiber supplementation is much less likely to help people who have serious dysmotility disorders, such as gastroparesis, or neuromuscular disorders such as those related to ALS, muscular dystrophy, or cerebral palsy. Patients who have evacuation problems secondary to chronic opiate use, pelvic floor disorders are also unlikely to respond to fiber supplementation. Constipation that results from other disorders, such as hypothyroidism or multiple sclerosis, will improve as the primary disorder is treated.

If a patient is already consuming 25-30 g of fiber per day, adding more is unlikely to help with constipation. However, if a patient is not consuming that much, increase intake very gradually (5 g/day) until the goal of 25-30 g/day is met. Because there are so many other reported health benefits from consuming more plant foods and meeting this goal for dietary fiber, dietitians should work with patients to educate them about the variety of health benefits, and ways to meet their fiber goals.

References and recommended readings

  1. Foxx-Orenstein AE, McNally MA, Odunsi ST. Update on constipation: one treatment does not fit all. Cleve Clin J Med. 2008;75(11):813-24.
  2. Schiller LR. Nutrition issues in gastroenterology, series #61. Nutrients and constipation: cause or cure? Pract Gastroenterol. 2008(4);43-49. http://www.practicalgastro.com/pdf/April08/PG_Apr08SchillerArticle.pdf. Accessed February 19, 2019.
  3. Suares NC, Ford AC. Systematic review: the effects of fibre in the management of chronic idiopathic constipation. Alimentary Pharmacol & Ther. 2011;33(8):895-901.
  4. Yang J, Wang HP, Zhou L, Xu CF. Effect of dietary fiber on constipation: A meta analysis. World J Gastroenterol. 2012;18(48):7378-83. doi:10.3748/wjg.v18.i48.7378.
  5. Woo HI, Kwak SH, Lee Y, Choi JH, Cho YM, Om AS. A controlled, randomized, double-blind trial to evaluate the effect of vegetables and whole grain powder that is rich in dietary fibers on bowel functions and defecation in constipated young adults. J Cancer Prev. 2015;20(1):64.

Page last reviewed/updated: February 19, 2018.