It's hard to find a processed food that does not contain emulsifiers, additives that are used to extend shelf life and improve texture. Now, a new study finds that emulsifiers can promote intestinal inflammation and colorectal cancer, the fourth-leading cause of cancer deaths.
Researchers at Georgia State University say they found that regular consumption of emulsifiers by mice altered intestinal bacteria in a way that contributed to tumor development.
Colorectal cancer caused about 700,000 deaths per year in the United States in 2012, the last year for which complete figures are available. And researchers note that the increasing death toll roughly corresponds to the rise of processed food consumption.
"The incidence of colorectal cancer has been markedly increasing since the mid-20th century," said Dr. Emilie Viennois, assistant professor in the Georgia State Institute for Biomedical Sciences. "A key feature of this disease is the presence of an altered intestinal microbiota that creates a favorable niche for tumorigenesis."
"The dramatic increase in these diseases has occurred amidst constant human genetics, suggesting a pivotal role for an environmental factor," said Benoit Chassaing, assistant professor in the Institute for Biomedical Sciences.
Earlier studies by the Georgia State research team suggested that low-grade inflammation in the intestine is promoted by consumption of dietary emulsifiers, which are detergent-like molecules incorporated into most processed foods that alter the composition of gut microbiota.
The addition of emulsifiers to food seems to fit the time frame surrounding colotrectal cancer. Viennois and Chassaing hypothesized that emulsifiers might affect the gut microbiota in a way that promotes colorectal cancer. They designed experiments in mice to test this possibility.
In the latest study, the team fed mice with two very commonly used emulsifiers, polysorbate 80 and carboxymethylcellulose, at doses seeking to model the broad consumption of the numerous emulsifiers that are incorporated into the majority of processed foods.
They found drastic changes in the gut microbiota in a manner that made it more pro-inflammatory, creating a niche favoring cancer induction and development.
The findings were published in the journal Cancer Research.
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