Many people commonly ate fiber-enriched foods to promote weight loss and prevent chronic diseases such as diabetes and cancer.
But in a study from The University of Toledo, scientists found in some—particularly those with a silent vascular deformity—consumption of highly refined fiber may increase the risk of liver cancer.
A refined, plant-based fermentable fiber, inulin is available in supermarkets as a health-promoting prebiotic. It is also a common ingredient in processed foods.
While inulin promotes metabolic health in most who consume it, the team discovered that about one in 10 standards, seemingly healthy lab mice developed liver cancer following consumption of the inulin-containing diet.
The new study offers a clear explanation—and may have implications that go beyond laboratory animals.
The researchers discovered all mice that developed malignant tumors had high concentrations of bile acids in their blood caused by a previously unnoticed congenital defect called a portosystemic shunt.
Normally, blood leaving the intestines goes into the liver where it is filtered before returning to the rest of the body.
When a portosystemic shunt is present, blood from the gut is detoured away from the liver and back into the body’s general blood supply.
The vascular defect also allows the liver to continuously synthesize bile acids. Those bile acids eventually spill over and enter circulation instead of going into the gut.
Blood that’s diverted away from the liver contains high levels of microbial products that can stimulate the immune system and cause inflammation.
To check that inflammation, which can be damaging to the liver, the mice react by developing a compensatory anti-inflammatory response that dampens the immune response and reduces their ability to detect and kill cancer cells.
While all mice with excess bile acids in their blood were predisposed to liver injury, only those fed inulin progressed to hepatocellular carcinoma, a deadly primary liver cancer.
Remarkably, 100% of the mice with high bile acids in their blood went on to develop cancer when fed inulin. None of the mice with low bile acids developed cancer when fed the same diet.
The team says dietary inulin is good in subduing inflammation, but it can be subverted into causing immunosuppression, which is not good for the liver.
Beyond the laboratory, the research could provide insight that might help clinicians identify people who are at higher risk of liver cancer years in advance of any tumors forming.
If you care about nutrition, please read studies about drinking diet soda linked to lower colon cancer risk, and Vitamin E may help prevent Parkinson’s disease.
For more information about nutrition, please see recent studies that green tea could strongly reduce blood pressure and results showing coffee drinking could help reduce death risk by decreasing heart rate.
The study was conducted by Dr. Matam Vijay-Kumar et al and published in the journal Gastroenterology.
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