Fifty grams of prunes, providing a daily fiber dose of 6 grams, outperformed an equal fiber dose from psyllium for constipation relief over three weeks, with the fruit’s laxative effects linked to its sorbitol, fiber, and polyphenol contents, according to findings of a study supported by the California Dried Plum Board.
“Given their palatability, tolerability and availability, dried plums should be considered in the initial approach to the management of mild to moderate constipation in the general population,” write the authors, led by Satish Rao, MD, PhD., from the University of Iowa Carver College of Medicine in Alimentary Pharmacology & Therapeutics.
According to the National Institute of Diabetes and Digestive and Kidney Disease (NIDDK), over four million Americans suffer from constipation every year. As a result, approximately $725 million is spent on laxatives in the US.
Constipation, considered a symptom and not a disease, is defined as fewer than three bowel movements per week.
Dietary approaches to alleviate constipation are well known, with prunes ranking high on the list of foods to help maintain regularity. However, while traditional use is well known, the University of Iowa researchers state that efficacy of this approach is not currently known.
Indeed, the European Food Safety Authority's (EFSA) Panel on Dietetic Products, Nutrition and Allergies (NDA) rejected an article 13.1 health claim in October 2010 of the long-standing association between prunes and bowel function due to insufficient evidence. The new study appears to fill some of the scientific gaps.
Dr Rao and his co-workers recruited 40 people with constipation to participate in their randomized control crossover trial. The average age of the participants was 38. Volunteers were randomly assigned to consume 50 grams per day of prunes, or 11 grams per day of psyllium (Metamucil, Proctor and Gamble Pharmaceuticals) for three weeks. One week of ‘washout’ separated the interventions.
Results showed that daily prune consumption significantly improved spontaneous bowel movements per week, compared with psyllium. The prune intervention increased spontaneous bowel movements per week from an average of 1.8 at the start of the study to 3.5, while psyllium was associated with an increase from an initial average of 1.6 to 2.8.
In addition, stool consistency measures also improved more in the prune group, compared with psyllium.
In terms of tolerability and palatability, there were no reported differences between prunes and psyllium, said the researchers.
“These findings confirm the general notion that dried plums that are widely consumed can be useful for the treatment of constipation,” wrote the authors.
Commenting on the potential benefits of prunes, the authors note that prunes contain about 15 grams of sorbitol per 100 grams, and this is known to act as an “osmotic laxative and holds on to water”, while there is also 184 milligrams of polyphenols per 100 grams, and six grams of fiber per 100 grams.
“Since we tested an equivalent dose of dietary fiber, it is likely that the clinical improvement observed with dried plums is most likely due to the other beneficial components of plums over and above its fiber content and ⁄ or the blend of soluble and insoluble fiber in this compound,” they added.
Source: Alimentary Pharmacology & Therapeutics
Volume 33, Issue 7, April 2011, Pages: 822–828, DOI: 10.1111/j.1365-2036.2011.04594.x
“Randomised clinical trial: dried plums (prunes) vs. psyllium for constipation”
Authors: A. Attaluri, R. Donahoe, J. Valestin, K. Brown and S. S. C. Rao