Prune powder

What is prune?

Prunes are dried plums from Prunus domestica. They are a traditional home remedy for constipation and contain a mix of insoluble and soluble fiber, the sugar alcohol sorbitol (which draws water into the bowel) and polyphenols. In supplements, prunes usually appear as a dried powder.

What the research says

Prunes have a small but solid body of human research. A 2014 systematic review in Alimentary Pharmacology and Therapeutics found four randomized trials. In people with constipation, 100 g of prunes a day for three weeks improved stool frequency and consistency compared with psyllium. In people without constipation, prunes softened stools in one trial and increased stool weight in another. The authors called prunes promising but said more rigorous research was needed.

A 2019 randomized controlled trial in Clinical Nutrition followed 120 healthy adults with low fiber intake and three to six stools a week. Eating 80 g or 120 g of prunes a day for four weeks increased stool weight and frequency compared with water alone. Prunes did not change gut transit time, and flatulence was more common with prunes.

In a 2021 US trial of adults with chronic constipation, 100 g of prunes a day increased complete bowel movements and improved stool consistency and straining, with results broadly similar to psyllium and kiwifruit.

How it’s used in supplements

The studied amounts are whole-food servings of 80 to 120 g a day. Digestive capsules that include prune powder in a multi-ingredient blend almost certainly provide a tiny fraction of that, so the trial results do not tell us much about a capsule. If prunes appeal to you, eating them (or drinking prune juice) is cheap and well supported. Increase gradually, since prunes can cause gas, and keep in mind that they contain natural sugars and calories.

Why do prunes work? They provide several mechanisms at once. Their insoluble fiber adds bulk, their soluble fiber and pectin hold water, and their sorbitol, a sugar alcohol that is poorly absorbed, draws water into the colon. Polyphenols in prunes may also influence gut bacteria; in the 2019 trial, Bifidobacteria rose modestly across groups. Prune juice keeps the sorbitol but loses much of the fiber, so whole prunes are usually preferred.

A practical approach is to start with three or four prunes a day and increase slowly over a week or two while drinking enough water. People who are sensitive to sorbitol, including some with irritable bowel syndrome, may find prunes trigger gas or loose stools and may do better with other fiber sources.