The additives in question, called emulsifiers, are used to increase the shelf life and improve the texture of processed food. (See more news about hazardous food ingredients at Ingredients.news)
Colon cancer is the fourth most lethal form of cancer worldwide. It kills about 700,000 people per year.
The new study is part of a growing field of research into the microbiome, the roughly 100 trillion microorganisms that coexist with the human body -- particularly in the gut -- and play critical roles in regulating everything from metabolism to immune function and even mood.
Prior studies have shown that people who suffer from a variety of metabolic and bowel conditions, including metabolic syndrome and inflammatory bowel disease (IBD), have abnormal microbiome compositions.
One study, conducted by the same Georgia State University team in conjunction with other researchers, found that the emulsifiers polysorbate 80 and carboxymethylcellulose caused inflammation-promoting changes to the gut microbiomes of mice. In mice with healthy immune systems, this increased inflammation led to metabolic syndrome. In mice with abnormal immune systems, it led to chronic colitis, a type of IBD. These effects did not occur in mice whose microbiomes had been eliminated using antibiotics.
Metabolic syndrome is a cluster of symptoms associated with increased risk of heart disease, type 2 diabetes, dementia and liver cancer. IBD is a risk factor for colon cancer.
Other research has shown that consuming food containing emulsifiers causes more bacteria to cross the epithelial cells that line the gut, another risk factor for colon cancer.
The incidence of IBD, colon cancer and the diseases linked to metabolic syndrome have all increased dramatically since emulsifiers were introduced in the mid-20th century.
Because studies have also shown abnormal microbiomes in people with colon cancer, the researchers decided to look directly at emulsifiers and colon cancer risk. They once again fed polysorbate 80 and carboxymethylcellulsose to mice, in concentrations similar to those found in processed food. As before, they found that the composition of the animals' gut microbiomes changed to favor inflammation.
Specifically, the microbiome shifted to include more bacteria that release higher levels of flagellin and lipopolysaccharide. These chemicals, in turn, trigger the immune system to produce inflammation.
Using a well established colorectal cancer model, the researchers found that the inflammatory environment in the mice's guts was enough to significantly increase their risk of developing colonic tumors, by shifting the cellular balance toward proliferation and away from apoptosis (programmed cell death).
These changes did not occur in mice without microbiomes. When the microbiomes of the emulsifier-fed mice were transplanted into microbiome-free mice, however, those mice also developed changes in epithelial cell homeostasis suggesting increased cancer risk.
The researchers are now investigating which microbiome species in particular mediate the observed changes, and how they do so.
The study is good news, in a sense, providing one more easy way to dramatically cut your risk of colon cancer.
Though highly deadly, colon cancer is also highly preventable. The disease's major risk factors include lifestyle factors like smoking, high alcohol consumption, lack of physical activity, obesity and a diet high in red and processed meats. Cut these toxic habits and lengthen your life.
There is also strong evidence that boosting your intake of fiber-rich foods such as fruits, vegetables, legumes and whole grains can dramatically decrease your risk. Fiber supplements do not seem to have the same effect, however. (RELATED: Learn about healthy food choices at Fresh.news)
In addition to reducing your colon cancer risk, these lifestyle changes will improve your overall bowel health and lower the risk of other chronic diseases, including heart disease, diabetes, Alzheimer's disease and other forms of cancer.
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