Refined fiber is link to liver cancer, study finds

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For years, people have turned to fiber-enriched foods to aid weight loss and safeguard against chronic diseases like diabetes and cancer.

However, a study conducted at The University of Toledo has revealed a concerning twist: the consumption of highly refined fiber may elevate the risk of liver cancer, especially in individuals with an unnoticed vascular defect.

This vascular anomaly can have implications beyond laboratory animals and offers a significant explanation for this unexpected correlation.

The Culprit: Refined, Plant-Based Fermentable Fiber (Inulin)

Inulin, a refined, plant-based fermentable fiber, is widely available in supermarkets as a health-promoting prebiotic and is also a common ingredient in processed foods.

While inulin generally promotes metabolic health in most individuals, the study uncovered a surprising outcome. About one in ten seemingly healthy lab mice developed liver cancer after consuming a diet containing inulin.

Understanding the Mechanism

The researchers made a crucial discovery: all mice that developed malignant liver tumors had elevated concentrations of bile acids in their blood.

This increase in bile acids was attributed to an unnoticed congenital defect known as a portosystemic shunt. Typically, blood from the intestines is filtered through the liver before re-entering the general blood supply.

However, in the presence of a portosystemic shunt, blood from the gut bypasses the liver and is directed back into the body’s overall blood circulation.

This vascular defect also allows the liver to continuously produce bile acids, which eventually spill into circulation instead of being directed into the gut.

Blood that circumvents the liver contains high levels of microbial products that can activate the immune system and trigger inflammation.

To counteract this inflammation, which can be harmful to the liver, the mice developed a compensatory anti-inflammatory response.

This response suppressed the immune system, reducing its ability to detect and combat cancer cells.

While all mice with excess bile acids in their blood were vulnerable to liver injury, only those fed a diet containing inulin progressed to hepatocellular carcinoma, a fatal form of primary liver cancer.

Strikingly, all mice with elevated bile acid levels in their blood developed cancer when given inulin, while none of the mice with lower bile acid levels developed cancer when fed the same diet.

The Implications

The research team emphasizes that dietary inulin has potential benefits in suppressing inflammation. However, it can also be manipulated to induce immunosuppression, which is detrimental to the liver.

Beyond the laboratory setting, this study could provide valuable insights for clinicians in identifying individuals at a higher risk of developing liver cancer long before tumors emerge.


The study uncovers a previously unknown link between refined fiber consumption and liver cancer, particularly in the presence of a congenital vascular defect.

It highlights the complexity of dietary components and their impact on health, urging caution in the widespread promotion of fiber-rich diets.

This research not only deepens our understanding of liver cancer risks but also underscores the importance of personalized dietary recommendations to ensure optimal health outcomes.

For those interested in nutrition, recent studies have explored the potential benefits of diet soda in reducing colon cancer risk and the role of Vitamin E in preventing Parkinson’s disease.

Additionally, research has investigated the effects of green tea on blood pressure and the potential life-extending benefits of coffee consumption.

The study was conducted by Dr. Matam Vijay-Kumar et al. and was published in the journal Gastroenterology.

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