Prunes are one of the few foods with a head-to-head clinical trial against a widely used fiber supplement, and they came out ahead.
In a randomized crossover study, 50 grams of prunes twice daily improved complete spontaneous bowel movements and stool consistency more than 11 grams of psyllium twice daily in adults with mild to moderate chronic constipation.
Psyllium is the active fiber in Metamucil.
The eight-week trial enrolled 40 constipated adults, ran each treatment for three weeks and was published in Alimentary Pharmacology and Therapeutics in 2011.
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Both treatments were rated safe and equally palatable, and the authors concluded that dried plums should be considered a first-line therapy for constipation.
Behind the effect are two things working at once. A serving of 4 to 6 prunes delivers about 3 grams of fiber, a mix of soluble and insoluble. Prunes also contain sorbitol, a sugar alcohol that pulls water into the intestines and softens stool.
What a year of prunes did for bone
Bones respond too. In the 12-month Prune Study at Penn State, 235 postmenopausal women were assigned to eat no prunes, 50 grams a day (about 4 to 6 prunes) or 100 grams a day.
After a year, women eating 50 grams daily preserved cortical bone density and estimated bone strength at the tibia, while the control group lost both.
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The trial found that 50 grams was the more practical target because the higher intake led more participants to drop out.
Researchers point to prunes' polyphenols, vitamin K, boron and potassium as likely contributors, though the trial did not isolate a single mechanism.
A quiet effect on blood sugar
Despite their sweetness, prunes carry a low glycemic index of 29. The reason lies in their composition.
Sorbitol is absorbed slowly, and the soluble fiber in prunes slows how quickly glucose reaches the bloodstream.
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A serving of 4 to 6 prunes contains about 24 grams of carbohydrates and 3 grams of fiber.
That does not make prunes a treatment for diabetes, and people managing blood sugar should still discuss dried fruit portions with their doctor. But the sweetness is not the whole story.
How to eat them without overshooting
The daily amount that shows up across the evidence is small. Four to six prunes, or roughly 50 grams, fits in a small handful and pairs easily with oatmeal, yogurt or a piece of toast.
Sorbitol has a dose-dependent laxative effect, so anyone new to prunes should build up gradually. Large jumps can cause bloating, gas or loose stools. When you add dietary fiber, do it slowly and drink water alongside.
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For someone starting from zero, a couple of prunes at breakfast for a few days, then working up to the 4 to 6 range, is enough to reach the doses used in the research.
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This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.