Bowl of prunes beside halved green kiwifruit and water

Natural Stool Softener: What You Need to Know

ByCraig Brockie Last updated

What a natural stool softener is

A natural stool softener is a food, drink or fiber that helps keep more water in your stool, so it comes out softer and easier to pass. The best-studied options are psyllium fiber, prunes, green kiwifruit and mineral-rich water, used along with enough fluids. They work more slowly than drugstore products and suit mild, everyday constipation rather than sudden or severe symptoms.

The term borrows from over-the-counter “stool softeners,” which usually means docusate. MedlinePlus explains that these products soften stools to make them easier to pass, usually take one to three days to work, and shouldn’t be used for more than a week unless a doctor says so. The NIDDK lists stool softeners alongside fiber supplements and osmotic laxatives as over-the-counter options for constipation.

This article is general information about food and fiber, not medical advice. It doesn’t replace advice from your own doctor or pharmacist, especially if you take medicines or have a health condition.

Why stool consistency is worth tracking

Stool form is one of the simplest gut measurements you can make at home. In a 1997 study of 66 volunteers, researchers in Bristol, England, found that a 7-point stool form scale tracked changes in how fast food moved through the gut better than how often people went. That scale, now called the Bristol Stool Form Scale, runs from hard separate lumps (type 1) to watery stool (type 7).

Hard, dry or lumpy stools that are tough to pass are classic signs of constipation, along with having fewer than three bowel movements a week, according to NIDDK. If you try a natural stool softener, noting your stool type and frequency for a couple of weeks shows whether it is helping. For lab-based gut testing, see our guide to stool tests for gut health.

Natural stool softeners and what the research shows

Here is how the main options compare, based on randomized trials and recent reviews. Most trials were small and short, so treat the results as a guide, not a guarantee.

OptionAmount used in studiesWhat the evidence shows
PsylliumAbout 10 to 12 g a daySoftened stool more than docusate in one trial; best-supported fiber supplement
Prunes80 to 120 g a day (about 8 to 13 prunes)More stool weight and frequency in two small trials
Green kiwifruit2 kiwis a daySimilar results to prunes and psyllium, fewer side effects
High-mineral waterVaries by brandBetter response than low-mineral water in a pooled analysis
MagnesiumStay at or under 350 mg a day from supplementsUsed in some laxatives; too much causes diarrhea

Psyllium

Psyllium is a soluble fiber that forms a gel and holds water. In a double-blind trial of 170 adults with chronic constipation, psyllium (5.1 grams twice a day) raised stool water content and total stool output more than docusate (100 mg twice a day) over two weeks. A 2022 review of 16 trials with 1,251 people found fiber supplements helped constipation overall, with psyllium, doses above 10 grams a day and at least four weeks of use giving the best results. Gas was more common with fiber, and the authors noted the studies varied a lot. Our fiber supplement guide compares types.

Prunes and prune juice

Prunes supply fiber plus sorbitol, a sugar alcohol that draws water into the gut. One analysis found 11.2 to 15.5 grams of sorbitol per 100 grams of prunes. USDA FoodData Central lists 7.1 grams of fiber per 100 grams, or about 0.7 grams in a single pitted prune. In a 4-week trial of 120 adults with low fiber intakes, 80 or 120 grams of prunes a day increased stool weight and frequency compared with water alone, though gas was more common. In a smaller crossover trial of 40 people with constipation, 50 grams of prunes twice a day beat psyllium for weekly bowel movements and stool consistency.

Green kiwifruit

Kiwifruit has fiber that holds a lot of water. In a US trial of 79 adults with chronic constipation, two green kiwifruit a day, 100 grams of prunes or 12 grams of psyllium all increased complete bowel movements over four weeks. Kiwifruit improved stool consistency and straining, had the fewest side effects and the fewest dissatisfied patients. One green kiwi of about 69 grams has roughly 2 grams of fiber, according to USDA FoodData Central.

Water, mineral water and fiber-rich meals

NIDDK advises adults to get 22 to 34 grams of fiber a day, add it a little at a time, and drink water and other liquids so fiber can soften stool. A 2024 review of 23 food studies found high-mineral water led to more people responding than low-mineral water, and rye bread beat white bread for stool frequency. The British Dietetic Association’s 2025 guidelines include recommendations on fiber supplements, kiwifruit, prunes, rye bread and high-mineral water, though most rest on low-certainty evidence. For everyday meal ideas, see best foods for gut health and stewed apples.

Magnesium

Magnesium pulls water into the bowel, which is why it appears in some laxatives. The NIH Office of Dietary Supplements warns that high intakes from supplements and medicines can cause diarrhea, nausea and cramping, and sets the adult upper limit for supplemental magnesium at 350 mg a day unless a health care provider advises otherwise. A 2023 joint guideline from two US gastroenterology societies gave fiber and magnesium oxide conditional recommendations for chronic constipation, meaning the evidence was weaker than for some prescription and over-the-counter drugs.

How to use natural stool softeners

Glass of water with a spoon of psyllium husk and oats
  • Start small: add one change at a time, such as two kiwis or a few prunes a day, so you can see what works.
  • Raise fiber slowly: NIDDK advises adding fiber a little at a time, since a sudden jump can cause gas and bloating.
  • Drink with it: NIDDK advises drinking plenty of water and other liquids when you eat more fiber or take a fiber supplement.
  • Give it time: most trials ran three to four weeks, and the fiber review found the best results after at least four weeks.
  • Track the results: note your stool type and frequency so you can tell whether the change is working.

For children, take a different approach. The NHS advises seeing a doctor if you think a child is constipated, and laxatives for children should only be given on medical advice. Our guide to signs of poor gut health in toddlers covers the warning signs.

When to see a doctor

Natural stool softeners are for mild constipation. According to NIDDK, see a doctor right away if constipation comes with:

  • Bleeding from the rectum or blood in the stool
  • Constant pain in the abdomen
  • Being unable to pass gas
  • Vomiting or fever
  • Lower back pain
  • Losing weight without trying

Also see a doctor if your symptoms don’t improve with self-care, or if you have a family history of colon or rectal cancer. If you rely on laxatives to go, NIDDK says to talk with your doctor about how to slowly stop using them.

Related topics

Sources

This article is for general information and is not medical advice. Talk to your doctor or a registered dietitian before changing your diet, supplements or medication, especially if you have a health condition.

Craig Brockie is the founder of Ultimate Health Solutions, the company behind Ultimate Gut, and the author of Ultimate Health, The Ultimate Gut Health Guide and The Unlimited Probiotics Guide. After injuries and chronic health problems in his twenties that conventional care didn’t resolve, he began researching health on his own and has studied natural health for 30 years. He is not a medical professional, and his articles are general information, not medical advice.

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