Kiwis, Prunes and Magnesium for Constipation: What a 2025 Dietary Guideline Found

Constipation gets more common with age, and the store is full of fixes: fiber powders, prune juice, kiwi capsules, magnesium and herbal laxatives. In 2025, the British Dietetic Association published the first evidence-based dietary guideline for chronic constipation, built on reviews of 75 randomized trials.¹ Here is what made the cut.

What the guideline supports

• Psyllium fiber helped more people get a clinical benefit, increased how often they went and softened stools.¹ Our guide to psyllium powder covers how to take it.
• Whole kiwifruit increased stool frequency more than psyllium did, though it didn’t soften stools more.¹
• Prunes performed about the same as psyllium for stool consistency and straining.¹ The fruit trials included 258 people.¹
• Magnesium oxide supplements helped more people get a benefit, increased frequency and softened stools, based on moderate-quality evidence.¹

What didn’t do as well

• Kiwifruit extract capsules didn’t improve stool frequency or consistency. Eating the fruit is the option with support.¹
• Senna supplements didn’t increase the number of people who benefited. In one study, 83% of people taking senna needed a lower dose because of belly pain or diarrhea.¹
• High-mineral water didn’t improve overall symptoms compared with low-mineral water.¹
• Rye bread increased stool frequency compared with white bread but made overall symptoms worse.¹

The authors noted that most of the evidence is low quality, and they made no recommendations about whole-diet approaches.¹

Magnesium cautions

Labels on magnesium laxatives say to ask a doctor first if you have kidney disease or are on a magnesium-restricted diet, and to check with a pharmacist if you take prescription medicines. They also say to stop and ask a doctor for rectal bleeding or if you need a laxative for more than a week.² Our guide to choosing a laxative compares other options.

When to get checked

A change in bowel habits lasting more than 2 weeks deserves a conversation with your clinician.² Our article on why you may be constipated so often explains common causes, including medicines.

A simple plan to discuss

1. Add one option at a time, such as two kiwis a day or a portion of prunes, for a few weeks.
2. Increase fiber gradually with plenty of fluids.
3. Ask about magnesium if food changes aren’t enough and your kidneys are healthy.
4. Track results so you know what works.

Try: “I’ve been constipated for months. Would kiwis, prunes or a magnesium supplement be safe for me with my kidneys and medicines, or should we check for a cause first?”

Bloated by Dinner includes a Belly Clock log and a Test-It list with a visit script. Use them to record what you eat, what you try and how your bowels respond. See the book.