Julia Freiberger

October 15, 2025, 2:24 am | Read time: 4 minutes

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Nutritional Therapies for Chronic Constipation Examined

An international research team evaluated 75 high-quality studies on nutritional therapy for chronic constipation in adults. The goal was to determine which foods, drinks, and supplements are proven to work–and which have no or even negative effects.

Notably, fresh kiwis showed a positive effect on digestion in several studies–sometimes even outperforming well-known home remedies like psyllium husks.¹

Also interesting: Is sauerkraut really that healthy?

Study Procedure

Only so-called randomized controlled trials (RCTs), considered particularly reliable, were examined. The researchers analyzed the effects of various dietary measures on the following points:

• Frequency of bowel movements
• Consistency of stool
• Complaints such as straining, bloating, or abdominal pain
• Quality of life
• Side effects such as diarrhea or intolerances

The recommendations were evaluated using the internationally recognized GRADE system, which assesses the strength of study findings. Statements were only included in the recommendation list if at least two studies supported them and at least 85 percent of experts agreed in a consensus process.

What Really Helps–and What Doesn’t?

The evaluation clearly distinguishes between effective, ineffective, and even partially problematic measures.

Helpful for Constipation:

• Psyllium (psyllium husks): Significantly increases the frequency of bowel movements, softens stool, and reduces straining during bowel movements.
• Magnesium oxide: Leads to almost four additional bowel movements per week, significantly softens stool, and many feel overall better. Clearly recommended because it reliably works according to study indications.
• Bifidobacterium lactis (probiotic): Can help increase bowel movement frequency but does not work for complaints like hard stool, pain, or bloating. Cautiously recommended–because the effect is limited, but the probiotic is well tolerated.
• Kiwis: Fresh kiwis led to slightly more frequent bowel movements compared to psyllium husks. They are considered well tolerated–especially for people who cannot tolerate other remedies like psyllium. Recommended–because the effect is convincing, even if the study situation is still limited.
• Rye bread: Increased stool frequency compared to white bread. However, complaints like bloating occurred more frequently. Only recommended with reservations.
• Mineral-rich water: Contains a lot of magnesium and sulfate. In studies, significantly more people reported improvement when they drank such water–although without noticeable impact on pain or stool consistency. Recommended as a supplementary measure.

Little to No Effect:

• Senna (senna leaves): Often used, but could not show reliable benefits in studies. The results were inconsistent.
• Synbiotics (combination of pro- and prebiotics): Showed no proven effect on constipation complaints.
• Polydextrose, inulin mixtures, galacto-oligosaccharides: These fibers showed no noticeable improvements.
• Kiwi fruit supplements (e.g., in capsule or powder form): Unlike fresh kiwis, no effect on digestion or complaints.

More on the topic

Expert Examines How Healthy Are Psyllium Husks Really?

Causes and Treatment Symptoms Indicating Leaky Gut Syndrome–and Potential Subsequent Diseases

Limitations of the Study Situation

Despite the large data base, there are important limitations:

• Many recommendations are based on smaller or shorter studies. Large long-term studies with uniform criteria are lacking.
• The conditions were often very different: Studies varied in dosage, duration, and target group. This makes the results difficult to compare.
• Few studies on entire diets: Mainly investigated how individual foods or remedies work–not how a complete diet with more fiber helps in the long term.
• Placebo comparison often not possible: With foods like bread or kiwi, it is difficult to test a “sham product.” This could lead to expectations influencing the result.
• Partially funded by manufacturers: Some studies were funded by companies that sell, for example, probiotics. This can affect the credibility.

Constipation–Kiwis, Psyllium Husks, and Magnesium Oxide Can Help

Many well-known home remedies for constipation do not work as often claimed.
Fresh kiwis, psyllium husks, and magnesium oxide are among the few natural remedies with proven effectiveness. Probiotic bacteria like Bifidobacterium lactis and mineral-rich water can also help–but not for all complaints.

Those suffering from chronic constipation can try a well-tolerated option with kiwis, magnesium oxide, or psyllium husks–ideally over several weeks. Important: Not every remedy works the same for everyone. What matters is what helps individually–and what doesn’t.