Common food additives, it turns out, may cause obesity and metabolic syndrome, among other conditions, according to a new study.
The additives in question are called emulsifiers, and are added to most processed foods to aid texture and extend shelf life. However, while they may make your food taste better, they can also alter the composition and localization of your gut microbiota, leading to inflammatory bowel disease (IBD). IBD includes Crohn's disease and ulcerative colitis, severely debilitating conditions that affect millions of people.
Emulsifiers are also reportedly linked to metabolic syndrome - a group of very common obesity-related disorders that can lead to type-2 diabetes, cardiovascular and liver diseases.
With both IBD and metabolic syndrome, gut microbial - that is, the 100 trillion bacteria that naturally live in the intestinal tract - are disturbed.
"A key feature of these modern plagues is alteration of the gut microbiota in a manner that promotes inflammation," co-lead author Dr. Andrew T. Gewirtz said in a statement.
"The dramatic increase in these diseases has occurred despite consistent human genetics, suggesting a pivotal role for an environmental factor," researcher Dr. Benoit Chassaing. "Food interacts intimately with the microbiota so we considered what modern additions to the food supply might possibly make gut bacteria more pro-inflammatory."
So how do these emulsifiers work? The researchers aren't exactly sure of the details, but they suggest that they promote the movement of bacteria across epithelial cells.
To test the theory, the team fed mice two commonly used emulsifiers: polysorbate 80 and carboxymethylcellulsose. They found that emulsifier consumption changed the species composition of the gut microbiota in a way that promoted inflammation and metabolic syndrome, characterized by increased levels of food consumption, obesity, hyperglycemia and insulin resistance.
"We do not disagree with the commonly held assumption that over-eating is a central cause of obesity and metabolic syndrome," Gewirtz said. "Rather, our findings reinforce the concept suggested by earlier work that low-grade inflammation resulting from an altered microbiota can be an underlying cause of excess eating."
And with lots of different foods containing emulsifiers, how is anyone safe? The researchers hope their results will lead to better means of testing and approving food additives like emulsifiers. Currents methods, it seems, are not able to prevent the use of chemicals that promote certain diseases.
The team is now testing additional emulsifiers and designing experiments to figure out how emulsifiers affect humans, versus mice. If similar results are obtained, it would indicate a role for this class of food additive in driving the epidemic of obesity, its inter-related consequences and a range of diseases associated with chronic gut inflammation.
This study follows recent research that indicates the food coloring compound 4-methylimidazole (4-MEI), known to give Coca Cola its iconic "caramel" coloring, may lead to cancer.
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