Goal · Regularity
Food for regularity: fiber, fluids, kiwifruit and prunes
Most adults eat well under the fiber they need. Raising it slowly, with fluid, is the first step; kiwifruit, prunes and psyllium all have trial support.
By the editors of Alimentotherapy Last reviewed 3 min read Not medical advice
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The short answer
For occasional constipation, the best-supported food step is more fiber, added gradually and taken with enough fluid: NIDDK advises 22 to 34 grams a day for adults, depending on age and sex NIH. In a US trial in people with chronic constipation, green kiwifruit, prunes and psyllium all increased complete bowel movements, with kiwifruit causing the fewest side effects Chey 2021.
Foods and herbs for regularity, graded
Every claim from our remedy pages that relates to regularity, strongest evidence first. Each row links to the full page and its sources.
| Food or herb | Grade | What the research found |
|---|---|---|
| PsylliumChronic constipation | Strong | A meta-analysis of 16 trials (1,251 adults) found 66 percent responded to fiber versus 41 percent to control, with psyllium among the fibers that worked; doses above 10 g a day for 4 weeks or more did best. |
| KiwifruitChronic constipation | Moderate | Two green kiwifruit a day for four weeks increased complete bowel movements by about 1.5 a week in functional constipation and by about 1.7 in IBS with constipation, and improved gut comfort. A pooled review found fruit, kiwifruit in particular, gave more bowel movements than psyllium. |
| PrunesChronic constipation | Moderate | In a 40-person crossover trial, 50 g of prunes twice a day improved complete bowel movements and stool consistency more than psyllium. In a pooled review of foods, prunes and psyllium came out about level. |
| PrunesStool output in healthy adults with low fiber intake | Moderate | In a trial of 120 adults, 80 g or 120 g of prunes a day for four weeks increased stool weight and frequency compared with water alone; flatulence was more common. |
| FlaxseedConstipation | Limited | In a 12-week trial of 53 constipated adults with type 2 diabetes, 10 g of flaxseed baked into cookies twice a day improved constipation scores compared with placebo cookies. Larger trials are lacking. |
| OatsConstipation | Limited | A review of foods for chronic constipation found only one oat bran trial, too little to grade with confidence; fiber supplements such as psyllium have far more evidence. |
Fiber and fluid: the base
Americans eat about 16 grams of fiber a day on average, against a recommendation of 21 to 38 grams for older children and adults MedlinePlus. NIDDK puts the adult range at 22 to 34 grams, and suggests whole grains such as oatmeal and whole wheat, legumes such as lentils and beans, fruit such as berries, pears and apples with the skin on, and vegetables NIH.
Two details matter. Add fiber a little at a time so your gut adjusts, and drink enough liquid to help the fiber work NIH. A sudden jump, especially from bran or a powder, is the usual cause of gas and bloating in the first week.
Most people have no idea how much fiber they eat. Logging a few ordinary days in a food diary such as Cronometer (the free tier is enough) shows whether you are at 12 grams or 30 before you change anything.
Kiwifruit, prunes and psyllium head to head
A 2021 exploratory trial in 79 US adults with chronic constipation compared green kiwifruit, prunes and psyllium over four weeks Chey 2021. All three increased the weekly number of complete spontaneous bowel movements. Kiwifruit and prunes improved stool consistency, all three reduced straining, and kiwifruit also improved bloating. Side effects were most common with psyllium and least common with kiwifruit, and fewer people were dissatisfied with kiwifruit at the end.
It was a small trial without a placebo group, so it shows the three are reasonable options rather than that one is clearly best. Pick the one you will actually eat every day. The AGA and ACG constipation guideline gives fiber a conditional recommendation and lists several over-the-counter laxatives with stronger evidence, such as polyethylene glycol, for when food changes are not enough Chang 2023.
In the kitchen
Psyllium swells with water: stir it into a full glass and drink it straight away, then have more fluid afterwards. Take it a couple of hours apart from medicines, because it can slow their absorption (see interactions).
How to try a change fairly
Change one thing, keep it up for at least two weeks, and note bowel movements, stool form and straining before and after. Many things shift regularity on their own: travel, illness, less movement, and medicines and dietary supplements NIH. If you start a new medicine and become constipated, ask your pharmacist before changing your diet to compensate.
When to see a clinician, not the pantry
- Bleeding from the rectum or blood in the stool.
- Constant belly pain, being unable to pass gas, vomiting, fever or lower back pain with constipation.
- Losing weight without trying.
- Symptoms that do not go away with self-care, or a family history of colon or rectal cancer.
Common questions
How much fiber should an adult eat a day?
NIDDK advises 22 to 34 grams of fiber a day for adults, depending on age and sex, while the average American eats about 16 grams. Increase it gradually and drink enough fluid so the extra fiber helps rather than causing gas and bloating.
Are kiwifruit or prunes better for constipation?
In a 2021 US trial in 79 adults with chronic constipation, green kiwifruit, prunes and psyllium all increased complete bowel movements over four weeks. Kiwifruit had the fewest side effects and the least dissatisfaction, but the trial was small and had no placebo group, so any of the three is a reasonable choice.
Sources
Primary research and government sources, each checked on the date this page was reviewed.
- SourceNational Institute of Diabetes and Digestive and Kidney Diseases (NIH). Eating, Diet, and Nutrition for Constipation.
- SourceNational Institute of Diabetes and Digestive and Kidney Diseases (NIH). Symptoms and Causes of Constipation.
- MedlinePlusMedlinePlus. Fiber.
- PubMedChey SW, et al. Exploratory comparative effectiveness trial of green kiwifruit, psyllium, or prunes in US patients with chronic constipation. Am J Gastroenterol. 2021. PMID 34074830.
- GuidelineChang L, et al. American Gastroenterological Association-American College of Gastroenterology clinical practice guideline: pharmacological management of chronic idiopathic constipation. Am J Gastroenterol. 2023. PMID 37204227.
Keep reading
- RemedyKiwifruitTwo green kiwifruit a day is one of the best-tested food approaches to constipation, and the gentlest on the gut. The sleep research is small and uncontrolled.
- RemedyPrunesThe old remedy holds up: in trials, a daily handful of prunes improved constipation about as well as a fiber supplement. Research on bone density is early.
- RemedyPsylliumThe seed husk sold as a bulk fiber. It has the best evidence of any fiber supplement for chronic constipation and a solid record on LDL cholesterol.
- RemedyOatsOne of the best-supported foods in this whole reference: the soluble fiber in oats, beta-glucan, lowers LDL cholesterol a little but reliably.
- GoalFood and digestive comfort: bloating, gas and sensitive gutsFor a sensitive gut, enteric-coated peppermint oil and a short, dietitian-guided low FODMAP trial have the strongest evidence. Most bloating comes from what and how fast we eat.