Refined fiber and liver cancer risk: insights from a study on inulin

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Fiber-enriched foods have long been recognized for their health benefits, including weight management and the prevention of chronic diseases like diabetes and cancer.

However, a recent study from The University of Toledo reveals that consuming highly refined fiber may increase the risk of liver cancer, particularly in individuals with a silent vascular deformity.

The study focused on inulin, a commonly available refined, plant-based fermentable fiber that is found in many processed foods and marketed as a health-promoting prebiotic.

While inulin generally promotes metabolic health, the research team discovered that a small subset of seemingly healthy lab mice developed liver cancer after consuming an inulin-containing diet.

The Link Between Inulin, Bile Acids, and Liver Cancer

The study sheds light on a previously unnoticed congenital defect called a portosystemic shunt, which is present in individuals who developed liver cancer after consuming inulin.

Normally, blood from the intestines passes through the liver for filtration before returning to the body. However, with a portosystemic shunt, blood from the gut bypasses the liver and flows back into the general bloodstream.

This defect leads to high concentrations of bile acids in the blood, as the liver continuously synthesizes them instead of diverting them into the gut.

The presence of excess bile acids in the blood triggers inflammation due to high levels of microbial products, which stimulates the immune system.

Immunosuppression and Hepatocellular Carcinoma

The mice with excess bile acids and the portosystemic shunt were predisposed to liver injury. However, only those mice fed an inulin-containing diet progressed to hepatocellular carcinoma, a primary liver cancer.

Remarkably, all mice with high bile acid levels developed cancer when fed inulin, while none of the mice with low bile acids developed cancer on the same diet.

The researchers found that dietary inulin, which is generally beneficial in reducing inflammation, can be subverted to cause immunosuppression.

This immunosuppression inhibits the immune system’s ability to detect and kill cancer cells, leading to the development of liver cancer.

The study’s findings not only offer insights into the effects of refined fiber on liver cancer but also potentially provide a means for clinicians to identify individuals at higher risk of liver cancer in advance.

By understanding the relationship between refined fiber, bile acids, and immunosuppression, healthcare professionals may be able to monitor and intervene in high-risk cases to prevent the development of liver cancer.

While fiber-rich diets are generally considered beneficial for health, the study highlights the potential risks associated with highly refined fiber, such as inulin, for individuals with specific underlying vascular defects.

The research underscores the importance of further investigations to fully understand the complex interactions between diet, gut health, and disease development.

As new insights emerge, it is essential to remain informed about nutrition and its impact on our well-being.

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