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When a phase two clinical trial from Japan suggested that a common constipation medicine might slow the progression of chronic kidney disease (CKD), paediatric nephrologist Dr Kanav Anand of Sir Ganga Ram Hospital, New Delhi, was not surprised.

Dr Anand believes the findings strengthen what clinicians in India have observed for years: the gut and kidneys are intimately linked, and ignoring constipation can silently worsen kidney damage.

“Japan's Tohoku University phase II trial offers hope: lubiprostone, a constipation drug, slowed adult CKD patients' eGFR decline by reshaping gut microbiota, boosting spermidine, and enhancing mitochondrial function," says Dr Anand.

He adds that the study provides a “proof-of-concept” that could shape future care strategies, including for Indian children with congenital kidney abnormalities.

A New Idea in Kidney Care: Treat the Gut to Protect the Kidneys

Chronic kidney disease remains a major public-health burden worldwide. As kidney function declines, toxins accumulate, dialysis becomes inevitable for many, and treatment options actually to slow this decline are limited.

Researchers in Japan began with a simple clinical observation: many people with CKD also struggle with constipation. Led by Professor Takaaki Abe at Tohoku University Graduate School of Medicine, the team wondered if this seemingly minor symptom could actually be worsening kidney damage.

“Constipation disrupts the intestinal microbiota, which worsens kidney function… we hypothesised that we could improve kidney function by treating constipation,” Abe explains.

This idea led to the first clinical trial evaluating lubiprostone, a well-known constipation drug, as a therapy to slow CKD progression.

What the Study Did

The study followed 150 adults with moderate CKD for 24 weeks:

• One group received a placebo, AND the other received lubiprostone (the constipation remedy drug)

• Researchers monitored two things: Levels of harmful gut-derived toxins that rise when kidneys weaken, AND eGFR, the gold-standard measure of kidney filtration

What the Study Found

• Toxin levels did not significantly change
• But patients on the higher dose of lubiprostone showed a much slower decline in kidney function than those on placebo
• In simple terms, their kidneys deteriorated more slowly

This marks the first clinical evidence that treating constipation might offer kidney protection.

How the Drug Works: Fixing the Gut to Help the Kidneys

Lubiprostone appears to help in ways beyond easing constipation:

• It reshapes gut microbiota
• This boosts spermidine, a natural molecule linked to healthier mitochondria
• Stronger mitochondria support kidney cells and slow damage

The concept reinforces the emerging “gut–kidney axis,” which Indian experts say is especially important for children.

Why the Gut–Kidney Link Is Critical in Indian Children

Constipation is widespread among Indian paediatric CKD patients. Dr Anand explains that while it affects about 30% of healthy children, the rates surge in CKD because of:

• Dietary restrictions
• Low fibre intake
• Medications
• Reduced physical activity

In conditions like vesicoureteric reflux (VUR), which are common in India, constipation can worsen kidney injury.

“In congenital anomalies like VUR, nearly half face bladder-bowel dysfunction, tripling UTI risk and scarring kidneys via bladder compression and dysfunctional voiding,” he notes.

This is where gut health becomes critical. Chronic constipation leads to gut dysbiosis, elevating uremic toxins (such as indoxyl sulfate and p-cresyl sulfate), increasing gut permeability, and triggering inflammatory pathways that accelerate CKD progression, even in children.

“For VUR kids, untreated constipation boosts UTIs, worsening renal damage,” he adds.

How the Japan Study Resonates in India

The Tohoku trial was conducted on adults, but its implications carry weight for Indian pediatric care. Dr Anand believes that while more research is needed, the concept of aggressively managing constipation could immediately benefit children with:

• CKD
• CAKUT (Congenital Anomalies of Kidney and Urinary Tract)
• Recurrent UTIs
• Bladder-bowel dysfunction

He emphasises that this trial reinforces what Indian doctors have long advocated: addressing the gut early may protect the kidneys later.

The Grey Areas: What We Still Don’t Know

• The study is a good lead to conduct larger trials, as it was relatively short (24 weeks)
• It slowed, but did not reverse, the kidney decline
• The exact gut bacteria involved are still unknown
• Not all patients may respond equally

Larger trials, including paediatric studies, are needed before lubiprostone can be widely recommended for kidney protection.

The Bottom Line

A pill long used for constipation may hold promise as a kidney-protecting therapy. For India, where pediatric kidney diseases, congenital anomalies, and constipation-driven UTIs are common, the findings are especially relevant.

Dr Anand believes the study should serve as a wake-up call: Treat constipation not as a minor inconvenience, but as an active risk factor for kidney injury.

If future studies confirm the benefits, a simple gut-targeting approach could become a powerful new tool to slow kidney disease, especially in vulnerable young patients.

(Kirti Pandey is a senior independent journalist)