Adding refined fiber to processed foods could create “serious” health risks, researchers warn

While the inulin-containing diet did stave off obesity, some of the mice began to develop jaundice. After six months, many of these mice developed liver cancer. However, the mice that developed liver cancer had preexisting dysbiosis, meaning an altered intestinal microbiota composition was found to play a central role in the promotion of liver cancer.

Amid growing understanding that the consumption of whole foods naturally rich in fiber can deliver strong health benefits, the researchers sought to test if a diet enriched with refined inulin would help combat obesity-associated complications in mice.

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“These findings indicate that enriching foods with purified fibers may not recapitulate the benefits of eating fruits and vegetables naturally rich in soluble fiber,” says Dr. Andrew Gewirtz, Professor in the Institute for Biomedical Sciences at Georgia State and one of the study's authors. 

“Moreover, it may result in serious, life-threatening liver cancer in some individuals. Hence, we think the recent FDA rule change that has effectively encouraged marketing of fiber-fortified food as health-promoting is ill-conceived and should be reconsidered,” he states.

Although this study was performed in mice, it has potential implications for human health, particularly cautioning against enriching processed foods with highly refined, fermentable fiber. This is particularly true for individuals with gut bacterial dysbiosis, in whom fiber consumption may lead to liver cancer, according to the findings of the study.

“Such a finding was really surprising,” says Dr. Matam Vijay-Kumar of the University of Toledo and senior author of the study, “However, at the same time we recognized their potential importance and accepted the challenge of exploring how processed dietary soluble fiber was inducing liver cancer.”

The study, published in Cell, used inulin from chicory root. This is not a food that humans would usually consume, the researchers point out. 

“We importantly demonstrated that soluble fiber, while it generally beneficially impacts health, can also become detrimental, leading to diseases as severe as liver cancer,” says Dr. Benoit Chassaing, Assistant Professor in the Neuroscience Institute at Georgia State.

“However, we do not want to promote that fiber is bad. Rather, our research highlights that fortifying processed foods with fiber may not be safe to certain individuals with gut bacterial dysbiosis, in whom consumption of purified fiber may lead to liver cancer.”

FDA green lights eight fiber ingredients
Earlier this year, the US Food and Drug Administration (FDA) issued guidance which identifies eight specific fibers that can be classified as “dietary fibers” on the upcoming Nutrition Facts Label, marking the end of two years of uncertainty for manufacturers. 

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The eight new fibers are mixed plant cell wall fibers (a broad category that includes fibers like sugar cane fiber and apple fiber, among many others); arabinoxylan; alginate; inulin and inulin-type fructans; high amylose starch (resistant starch 2); galactooligosaccharide; polydextrose; and resistant maltodextrin/dextrin.

Within the FDA ruling is the inulin fiber used in the study.

Speaking to NutritionInsight at the time, Paul Vennik, Director Sales & Marketing of Sensus who manufacture Frutafit (inulin) and Frutalose (oligofructose) chicory root fiber, said the ruling, “gives the food industry, by working with chicory root fiber as a dietary fiber, a great tool in hand to develop ‘better for you’ products that contribute to consumer health and thereby they add value to their products.”

Beneo's chicory root fibers also entered the approved list; Orafti inulin and oligofructose. “This decision means that consumers can continue to access great tasting fiber naturally sourced from chicory roots, without any labeling confusion. We are excited to be working with both new and existing customers to develop great new ways to help more consumers benefit from chicory root fiber,” said Anke Sentko, Vice President Regulatory Affairs & Nutrition Communication at Beneo.

Speaking on the findings of this study, a Beneo spokesperson noted, “after a first glance at the study from a scientific point of view we would say that the findings may need to be considered with extreme caution for the following reason: This animal study uses genetically modified mice whose immune system response is compromised and by no means comparable to a normal function. Overall, the complete study design is highly artificial and seems to lack adequate controls. Therefore, extrapolation of the results to humans is more than questionable.”

A Tate and Lyle spokesperson further highlighted issues with the study, “additional caution should be taken when interpreting results where unrealistic levels of one ingredient are added to a diet that is not representative of dietary guidelines nor current intake patterns. Extensive human research has been conducted leading to the approved use of multiple soluble dietary fibers by health authorities worldwide, including the US Food and Drug Administration (FDA). The consensus of science confirms that isolated or synthetic soluble dietary fibers provide many health benefits and can fit within a healthy balanced diet.” 

By Laxmi Haigh

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