Sometimes, it can be hard to follow dietary recommendations despite new dieting ideas and trends.
Diets frequently need to be varied and adapted based on individual needs and health hazards because everyone’s nutritional requirements are unique. In a recent Gastroenterology study, the risk of getting liver cancer in mice fed diets high in fermentable fibre was examined. The scientists discovered that feeding mice with a particular congenital abnormality a diet richer in fermentable fibre significantly increased their risk of developing liver cancer. These mice also exhibited a significant bile acid concentration in their blood.
According to the American Cancer Society, liver cancer accounts for over 700,000 deaths worldwide each year.
Based on this and additional data from people, the researchers suggest that screening for bile acid levels may help to predict liver cancer risk. People with higher bile acid levels may need to exercise caution regarding the amount of fiber-enriched processed foods they eat.
Fermentable fiber refers to types of fiber that the gut bacteria can ferment and break down. Food manufacturers will sometimes add highly refined, fermentable fiber to processed foods.
Brian Power, RD, nutrition expert and registered dietician not involved in the study, explained that “Food processing techniques can make fiber fermentable, which means it can be broken down by gut bacteria and produce many byproducts that are good for your health.”
Examples of processed foods containing highly refined, fermentable fiber include convenience foods like snacks and cereals fortified with fiber. But foods containing highly refined, fermentable fiber may not a healthy choice for everyone. Some people in specific subgroups, such as those at risk for liver cancer, may need to be cautious about diets high in fermentable fiber, as indicated by the new research.
“Liver cancer is increasingly serious in the U.S. and is projected to be the third deadliest cancer within this decade,” said Dr. Yiing Lin, Ph.D., a liver surgeon with Siteman Cancer Center at Washington University in St. Louis, who was not involved in the study.
For the study, the authors researched how a few different components may be related to liver cancer risk. Researchers examined mice that had a specific congenital defect called a portosystemic shunt, which impacts blood flow and exchange between the liver and the rest of the body. These mice had a higher risk for liver cancer. When the at-risk mice ate fermentable fiber-enriched diets, their risk of developing liver cancer increased. Researchers theorized that this could be because the fermentable fiber diet contributed to a suppressed immune system. What’s more, the mice had high levels of bile acids related to the portosystemic shunts. The liver makes bile acids out of cholesterol. Bile acids help the body digest and absorb fat.
While it was difficult to thoroughly study portosystemic shunts in humans, researchers could examine bile acid levels. They looked at the bile acid levels in men who developed liver cancer and matched these participants with controls that did not develop liver cancer.
They found that bile acid levels were about double for the men who developed liver cancer later in life. This indicates that screening for this could be helpful in the prediction of liver cancer. Next, researchers looked at overall fiber intake and associated liver cancer risk in humans. Among men with high bile acid levels, high fiber intake was associated with an increased risk of developing liver cancer.
Overall, the study notes a potential screening method for liver cancer and the potentially cautious use of fermentable fiber in certain at-risk groups. Dr. Lin noted the following:
“The findings are that in the setting of congenital portosystemic shunts in mice, fermented fiber-rich diets increase the chance of developing liver cancer. In humans, congenital portosystemic shunts are not common, but shunts develop in patients with cirrhosis. The findings in the study could help patients with liver disease and decrease their chances of developing liver cancer by diet modifications or other interventions.”
The study had several limitations, and further research is needed before experts can genuinely understand how diets high in processed fiber influence liver cancer risk. First, the initial data is from mice studies, which can only provide so much information. The data from people was only from men, indicating further diverse follow-up is needed. Researchers could not distinguish between fiber types in their data from human subjects. This means that further research is needed to understand if it is actually fermentable fiber that contributes to liver cancer risk.
Researchers also note that further research is needed on the prevalence of congenital liver shunts and how they impact liver disease and liver cancer.
Parvathy Sukumaran 
