Attaluri A, Donahoe R, Valestin J, Brown K, Rao SS. Randomised clinical trial: dried plums (prunes) vs. psyllium for constipation. Aliment Pharmacol Ther. 2011;33(7):822-828.
An 8-week, single-blind, randomized cross-over study.
Forty constipated subjects, 3 of whom were male and the remainder female, with a mean age of 38
Subjects received either prunes or psyllium to provide 6 grams per day of fiber for 3 weeks. After a 1-week washout period, therapies were switched.
The test subjects maintained a daily symptom and stool diary in which they tracked number of complete spontaneous bowel movements per week, global relief of constipation, stool consistency, straining, tolerability, and taste.
The number of complete spontaneous bowel movements per week (primary outcome measure) and stool consistency scores improved significantly (P<0.05) with dried plums when compared to psyllium.
Prunes work. That is, prunes appear to do exactly what everyone has always thought they do; they act as a mild laxative. Although some would think this action is obvious, this study by Attaluri et al may be among the first human clinical trials published in the peer-reviewed literature that demonstrates prunes' efficacy.
The results of a 2002 clinical trial comparing the effects of prunes versus dried apples on factors that affect bone density “suggest that dried plums may exert positive effects on bone in postmenopausal women.”1 Though the results were favorable, they did not confirm whether prunes act as laxatives.2
Two 2010 studies hinted that prunes might act as stool softeners. Both studies compared eating prunes as a snack against cookies. A June 2010 paper that appeared in the journal Appetite informed us that prunes were more effective than sugar cookies at suppressing hunger and creating a sense of satiety.3 A September 2010 article in the Journal of the American Dietary Association reported that snacking on prunes lowered triglyceride levels more than sugar cookies and mentioned a tendency for prunes to soften stools.4
Few experienced practitioners or consumers will view these data as new. Instead most will be surprised that this study had to be done in the first place.
There is another paper involving prunes that is worth noting. Appearing in the Journal of the American College of Nutrition in 2007, a review paper compared the effect of eating prunes against eating berries or other fruits on serum antioxidant capacity (AOC). While data from a series of clinical trials "demonstrated that consumption of certain berries and fruits such as blueberries, mixed grape and kiwifruit "increased plasma AOC,” eating prunes or drinking prune juice did not alter measured levels of antioxidant capacity.5
With the publication of the current Attaluri et al study, the use of prunes as a laxative has taken the first step away from being the product of “old wives’ tales” (OWT) toward the realm of evidence based medicine (EBM). Adherents of EBM may now prescribe prunes to patients suffering from constipation with less fear of criticism. It should be pointed out that there are weaknesses to this current study: It was single not double-blinded, participants were overwhelmingly female, little is known regarding the etiology of participants' constipation, and obviously, one study is far from conclusive.
This new advancement in medicine does have an element of the absurd to it. Few experienced practitioners or consumers will view these data as new. Instead most will be surprised that this study had to be done in the first place; the action of prunes on the human digestive tract is self-evident.
The attraction that many us have to EBM, and our resultant desire to find support for therapies in published studies, meta-analyses, or—the Holy Grail of all papers—the Cochrane Reviews, on the surface seems both reasonable and commendable but may become an obstruction to achieving best patient outcomes.
Until now, the evidence suggested we employ psyllium seed fiber as it is more efficacious than sodium docusate.6 Yet practitioners who rely on anecdote, commonsense, and the data obtained via OWT have been using prunes to soften and increase stool frequency all along.
This story about prunes brings to mind how my colleague Steve Austin, ND, when writing years ago about breast cancer, pointed out the distinction between type 1 and type 2 errors in statistics and how different medical professions put greater emphasis on preventing one form of error over the other. For a medical oncologist who prescribes chemotherapy, the demand is to be sure the drugs will have benefit against the cancer. One needs to be certain the drugs will bring benefit as the side effects are so great.7 For naturopathic doctors who employ nontoxic therapies, in this case prunes, the demands should be the opposite. If there is a chance a therapy may help, then we should be interested in trying it: the classic ‘it won’t hurt and it might help’ view of practice.
As for prunes, however, we can now prescribe them with confidence; they have officially graduated from unproven OWT to the trustworthy EBM.