Dietary emulsifiers promoted colon cancer in a mouse
model by altering gut microbes and increasing gut
inflammation. The findings give insights into how
emulsifiers in the diet could alter gut microbiota
and increase the risk of developing colorectal
cancer.

Mice fed dietary
emulsifiers in their drinking water (top) showed
higher levels of intestinal cell death (green stain)
than mice given plain water (bottom).Chassaing lab,
Cancer Research.
Our digestive tracts are
home to trillions of microbes, including bacteria,
fungi, and viruses. This microbial community,
collectively known as the gut microbiota, plays a
role in illness and health. Changes in these
microbes have been associated with several diseases
including obesity, type 2 diabetes, and irritable
bowel syndrome.
Dietary emulsifiers,
which are chemically similar to detergents, are
added to many processed foods to improve texture and
extend shelf life.
Scientists at Georgia State University previously
found that mice fed low levels of common dietary
emulsifiers developed altered gut microbiota and a
thinned mucus barrier protecting the lining of their
intestines. The mice also developed low-grade
intestinal inflammation and metabolic syndrome—a
group of conditions that increase the risk for type
2 diabetes, heart disease, and stroke.
Intestinal inflammation
is a known risk factor for colorectal cancer. In
their latest study, the scientists investigated
whether dietary emulsifiers might affect the risk
for colorectal cancer by altering the gut microbiota.
The research was funded in part by NIH’s National
Institute of Diabetes and Digestive and Kidney
Diseases (NIDDK). Results were published online on
November 7, 2016, in Cancer Research.
The team fed mice
standard chow and either plain drinking water or
water with 1% of the commonly used dietary
emulsifiers carboxymethylcellulose or
polysorbate-80. This dose was designed to model the
diets of people who eat large amounts of processed
foods.
Mice fed either of the
dietary emulsifiers for 9 weeks developed chronic,
low-grade intestinal inflammation and impaired
glucose metabolism.
The increased risks
conferred by inflammatory bowel disease (IBD) to the
development of colorectal cancer (CRC) gave rise to
the term "colitis-associated cancer" and the concept
that inflammation promotes colon tumorigenesis.
The researchers next
tested a chemically induced model of
colitis-associated cancer. When given a cancer
agent, mice fed emulsifiers for 90 days had greater
intestinal inflammation and tumor development than
mice that didn’t get the emulsifiers.
The team found that mice
fed the emulsifiers had less gut microbiota
diversity and increased levels of inflammatory
molecules.
The intestinal epithelial cells of mice fed the
emulsifiers also had higher levels of both cell
death and proliferation.
Increased cell turnover is known to play a role in
tumor development.
When the scientists fed
emulsifiers to germ-free mice, which don’t have gut
microbiota, these effects didn’t appear.
This finding suggests
that the effects of the emulsifiers were caused by
altering the gut microbiota. When gut microbes from
emulsifier-fed mice were transferred into germ-free
mice that hadn’t been fed emulsifiers, the germ-free
mice developed some of the abnormalities.
These results hint that
changes in the gut microbiota caused by dietary
emulsifiers may play a role in promoting tumor
development.
“The incidence of
colorectal cancer has been markedly increasing since
the mid-20th century,” first author Dr. Emilie
Viennois notes. “A key feature of this disease is
the presence of an altered intestinal microbiota
that creates a favorable niche for tumorigenesis.”
Whether dietary emulsifiers in the human diet have a
similar effect will be a subject for future study.
For more information
Cancer Research
Dietary emulsifier-induced low-grade inflammation
promotes colon carcinogenesis
Link...
U.S. National Institutes
of Health
Link...
Jama Surgery
Increasing Disparities in the Age-Related Incidences
of Colon and Rectal Cancers in the United States,
1975-2010
Link...
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