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Recent Marijuana Use Is Associated with Decreased Risk of Constipation

Key findings

  • In a nationally representative sample of U.S. adults, recent users of marijuana had 32% lower odds of constipation compared with past or never users
  • The odds of constipation did not differ between past and never users of marijuana
  • There was no relationship between marijuana use and diarrhea

The endogenous cannabinoid receptors in the gastrointestinal tract are known to influence bowel physiology, including motility (constipation and diarrhea). However, little is known about how cannabinoid compounds from marijuana use affect bowel motility.

In analyzing nationally representative data on U.S. adults, Adeyinka Adejumo, MD, at North Shore Medical Center, Kyle Staller, MD, MPH, director of the Gastrointestinal Motility Laboratory at the Center for Neurointestinal Health at Massachusetts General Hospital, and colleagues linked recent marijuana use with decreased risk of constipation. Their findings, the first from a population-based study of marijuana and bowel function, appear in The American Journal of Gastroenterology.

Study Methods

The researchers identified 9,645 adults, ages 20 to 59, who responded to both the drug use and bowel health questionnaires on the National Health and Nutrition Survey (NHANES) between 2005 and 2010.

NHANES asks participants to report their bowel movement frequency and to view color picture cards that match the Bristol Stool Form Scale (BSFS), then report the type of stool that is most usual for them. In this study, constipation was defined as either BSFS type 1 or 2, less than three bowel movements per week or both. Diarrhea was defined as either BSFS type 6 or 7, more than 21 bowel movements per week or both.

The NHANES drug use questionnaire included two questions about marijuana use: "Have you ever, even once, used marijuana or hashish?" and "During the past 30 days, on how many days did you use marijuana or hashish?" Participants were classified as never users of marijuana, recent users (within the past 30 days) or past users (those who have used marijuana but not within the past 30 days).

Marijuana Use and Bowel Movement

When bowel function was assessed according to the BSFS, recent marijuana users were less likely than past or never users to report constipation (5.2% vs. 6.7% vs. 8.1%, respectively).

When bowel function was assessed according to bowel movement frequency, there were no significant differences between groups in the frequency of constipation.

On multivariate analyses adjusted for demographic characteristics, comorbidities and diet, recent users of marijuana had 32% decreased odds of constipation (OR, 0.68; 95% CI, 0.52–0.89; P = .006) compared with past and never users. The odds of constipation did not differ between past and never users.

There was no relationship between marijuana use and diarrhea in either univariate or multivariate analyses.

An Age-old Remedy

The marijuana plant seed, Fructus cannabis, has been used to treat constipation for centuries. A recent randomized, double-blind trial, published in the American Journal of Gastroenterology, showed that hemp seed pills high in Fructus cannabis were substantially more effective than senna or placebo in relieving constipation, and through eight weeks of follow-up, as published in Clinical Gastroenterology and Hepatology, the laxative effect was more sustained.

In the current study, the absolute difference between marijuana users and nonusers in the frequency of constipation was modest (2%–4%). However, the NHANES drug use questionnaire is not administered to people ages 60 and older, who are more likely than younger adults to experience constipation, and that exclusion may have skewed the results.

Furthermore, constipation is highly prevalent—research published in the aforementioned Clinical Gastroenterology and Hepatology study shows it affects 16% of the population worldwide and 34% of the elderly. Therefore, even small changes in its frequency could have profound implications for health care costs and the individual burden of the condition.

Future research is warranted to address issues such as how bowel function is affected by the strain of marijuana, mode of intake (ingested or inhaled) and quantity consumed.

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