Diets High in Processed Fiber May Increase Cancer Risk

The outcomes spotlight each the necessity for routine blood bile acid stage testing in addition to warning when people with excessive bile acid ranges devour fiber. 

The research discovered that males who had excessive fiber consumption and excessive blood bile acid ranges had a 40% larger danger of liver most cancers. 

Fiber-enriched meals are sometimes consumed by many people to advertise weight reduction and fend towards persistent ailments like most cancers and diabetes.

Consuming extremely refined fiber, nonetheless, could elevate the chance of liver most cancers in sure individuals, particularly these with a silent vascular deformity, based on a latest research from The College of Toledo.

The discovering, which is described in a report revealed within the journal Gastroenterology, provides to UToledo’s increasing physique of data concerning the undervalued position that our intestine performs within the origin of illness.

“We have now labored for a very long time on this concept that each one ailments begin from the intestine,” mentioned Dr. Matam Vijay-Kumar, a professor within the Division of Physiology and Pharmacology within the School of Medication and Life Sciences and the paper’s senior writer. “This research is a notable development of that idea. It additionally offers clues that will assist determine people at a better danger for liver most cancers and doubtlessly allow us to decrease that danger with easy dietary modifications.”

Matam Vijay Kumar and Beng San Yeoh

From left, Dr. Matam Vijay-Kumar, a professor within the Division of Physiology and Pharmacology, and Dr. Beng San Yeoh, a postdoctoral fellow. Credit score: College of Toledo

Increasing Analysis

Vijay-Kumar’s group revealed a serious paper within the journal Cell in 2018 that exposed a big proportion of mice with immune system faults developed liver most cancers after being given an inulin-fortified weight-reduction plan.

Inulin is a refined, plant-based fermentable fiber that’s offered in supermarkets as a health-promoting prebiotic. Moreover, it’s typically present in processed meals.

Vijay-Kumar and colleagues discovered that round one in ten common, in any other case wholesome lab mice acquired liver most cancers after consuming the inulin-containing weight-reduction plan, even though inulin promotes metabolic well being within the majority of those that devour it.

“That was very shocking, given how hardly ever liver most cancers is noticed in mice,” mentioned Vijay-Kumar, who can be director of the UToledo Microbiome Consortium. “The findings raised actual questions concerning the potential dangers of sure refined fibers, however solely now can we perceive why the mice had been growing such aggressive most cancers.”

The brand new research gives a transparent rationalization — and should have implications that transcend laboratory animals.

A Lacking Hyperlink

Because the group furthered its investigation, the researchers found all mice that developed malignant tumors had excessive concentrations of bile acids of their blood brought on by a beforehand unnoticed congenital defect referred to as a portosystemic shunt.

Usually, blood leaving the intestines goes into the liver the place it’s filtered earlier than returning to the remainder of the physique. When a portosystemic shunt is current, blood from the intestine is detoured away from the liver and again into the physique’s basic blood provide.

The vascular defect additionally permits the liver to constantly synthesize bile acids. These bile acids ultimately spill over and enter circulation as an alternative of going into the intestine.

Blood that’s diverted away from the liver comprises excessive ranges of microbial merchandise that may stimulate the immune system and trigger irritation.

To test that irritation, which might be damaging to the liver, the mice react by growing a compensatory anti-inflammatory response that dampens the immune response and reduces their skill to detect and kill most cancers cells.

Whereas all mice with extra bile acids of their blood had been predisposed to liver damage, solely these fed inulin progressed to hepatocellular carcinoma, a lethal major liver most cancers.

Remarkably, 100% of the mice with excessive bile acids of their blood went on to develop most cancers when fed inulin. Not one of the mice with low bile acids developed most cancers when fed the identical weight-reduction plan.

“Dietary inulin is sweet in subduing irritation, however it may be subverted into inflicting immunosuppression, which isn’t good for the liver,” mentioned Dr. Beng San Yeoh, a postdoctoral fellow and the brand new paper’s first writer.

Dr. Bina Joe, Distinguished College Professor and chair of the Division of Physiology and Pharmacology, and a co-author of the research mentioned the high-impact publication demonstrates the pioneering analysis being executed at UToledo.

“The position of the intestine and intestine micro organism in well being and illness is an thrilling and necessary space of analysis, and our group is offering new insights on the vanguard of this discipline,” she mentioned.


Past the laboratory, UToledo’s analysis might present perception that may assist clinicians determine people who find themselves at larger danger of liver most cancers years upfront of any tumors forming.

Portosystemic shunts in people are comparatively uncommon — the documented incidence is just one in 30,000 individuals at start. Nonetheless, on condition that they often trigger no noticeable signs, the true incidence could also be many instances larger. Portosystemic shunting additionally generally develops following liver cirrhosis.

Theorizing that prime bile acid levels might serve as a viable marker for liver cancer risk, Vijay-Kumar’s team tested bile acid levels in serum samples collected between 1985 and 1988 as part of a large-scale cancer prevention study.

In the 224 men who went on to develop liver cancer, their baseline blood bile acid levels were twice as high as men who did not develop liver cancer. Statistical analysis also found individuals with the highest blood bile acid levels had a more than four-fold increase in the risk of liver cancer.

The research team also sought to examine the relationship between fiber consumption, bile acid levels, and liver cancer in humans.

While existing epidemiological studies don’t differentiate between soluble and non-soluble fiber, researchers could look at fiber consumption in concert with blood bile acids.

There are two basic types of naturally occurring dietary fiber, soluble and insoluble. Soluble fibers are fermented by gut bacteria into short-chain fatty acids. Insoluble fibers pass through the digestive system unchanged.

Intriguingly, researchers found high total fiber intake reduced the risk of liver cancer by 29% in those whose serum bile acid levels were in the lowest quartile of their sample.

However, in men whose blood bile acid levels placed them in the top quarter of the sample, high fiber intake conferred a 40% increased risk of liver cancer.

Taken together, Yeoh and Vijay-Kumar say the findings suggest both the need for regular blood bile acid level testing and a cautious approach to fiber intake in individuals who know they have higher-than-normal levels of bile acids in their blood.

“Serum bile acids can be measured by a simple blood test developed over 50 years ago. However, the test is usually only performed in some pregnant women,” Vijay-Kumar said. “Based on our findings, we believe this simple blood test should be incorporated into the screening measurements that are routinely performed to monitor health.”

And while the researchers are not arguing broadly against the health-promoting benefits of fiber, they are urging attention to what kind of fiber certain individuals eat, underscoring the importance of personalized nutrition.

“All fibers are not made equal, and all fibers are not universally beneficial for everyone. People with liver problems associated with increased bile acids should be cautious about refined, fermentable fiber,” Yeoh said. “If you have a leaky gut liver, you need to be careful of what you eat, because what you eat will be handled in a different way.”

References: “Enterohepatic Shunt-Driven Cholemia Predisposes to Liver Cancer” by Beng San Yeoh, Piu Saha, Rachel M. Golonka, Jun Zou, Jessica L. Petrick, Ahmed A. Abokor, Xia Xiao, Venugopal R. Bovilla, Alexis C.A. Bretin, Jesús Rivera-Esteban, Dominick Parisi, Andrea A. Florio, Stephanie J. Weinstein, Demetrius Albanes, Gordon J. Freeman, Amira F. Gohara, Andreea Ciudin, Juan M. Pericàs, Bina Joe, Robert F. Schwabe, Katherine A. McGlynn, Andrew T. Gewirtz and Matam Vijay-Kumar, 18 August 2022, Gastroenterology.
DOI: 10.1053/j.gastro.2022.08.033

“Dysregulated Microbial Fermentation of Soluble Fiber Induces Cholestatic Liver Cancer” by Vishal Singh, Beng San Yeoh, Benoit Chassaing, Xia Xiao, Piu Saha, Rodrigo Aguilera Olvera, John D. Lapek Jr., Limin Zhang, Wei-Bei Wang, Sijie Hao, Michael D. Flythe, David J. Gonzalez, Patrice D. Cani, Jose R. Conejo-Garcia, Na Xiong, Mary J. Kennett, Bina Joe, Andrew D. Patterson, Andrew T. Gewirtz and Matam Vijay-Kumar, 18 October 2018, Cell.
DOI: 10.1016/j.cell.2018.09.004

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