From the Tufts Health & Nutrition Letter:
Long the object of jokes, prunes now have the last laugh. New research demonstrates that prunes (dried plums) are more effective than psyllium fiber in combating constipation. The randomized control crossover trial with 40 constipated subjects, average age 38, compared 50 grams (about 1.76 ounces) daily of prunes with 11 grams of psyllium (Metamucil) for three weeks each, with a one-week "washout" period in-between. Both dosages supplied the same amount of dietary fiber, 6 grams. The prune regimen improved regularity by 94%, compared to 75% for the psyllium; measures of stool consistency also improved more when subjects were consuming prunes. Since the two regimens delivered identical amounts of fiber, researchers suggested that other nutrients in prunes such as sorbitol and polyphenols might be responsible for the difference. The study was funded by the California Dried Plum Board but conducted independently at the University of Iowa. - Alimentary Pharmacology & Therapeutics
And prunes test better too!