We all know that we should be careful about what we eat. But did you know that a widely used food additive may actually promote obesity? Scientists have found that emulsifiers, which are added to most processed foods to aid texture and extend shelf life, can promote colitis, obesity and metabolic syndrome.
But how exactly do emulsifiers do this? It all has to do with how they alter gut bacteria. "Gut microbiota" refers to the diverse population of 100 trillion bacteria that inhabit our intestinal tracts. When gut microbiota are disturbed, a person can develop inflammatory bowel disease (IBD) and metabolic syndrome. IBD, which includes Crohn's disease and ulcerative colitis, affects millions of people. Metabolic syndrome is a group of very common obesity-related disorders that can lead to type-2 diabetes, cardiovascular and/or liver diseases.
Emulsifiers have been shown to promote bacterial translocation across epithelial cells. In order to see if emulsifiers might affect gut microbiota to promote these inflammatory diseases, they turned to mice.
The scientists fed mice two very commonly used emulsifiers: polysorbate 80 and carboxymethylcellulsose. Both of these were fed at doses that modeled the broad consumption of the numerous emulsifiers that are incorporated into almost all processed foods. In the end, they found that the emulsifiers changed the species composition of the gut microbiota and did so in a manner that made it more pro-inflamatory.
In fact, the changes triggered chronic colitis in mice genetically prone to this disorder, due to abnormal immune systems. Mice with normal immune systems suffered from low-grade or mild intestinal 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," said Andrew Gewirtz, one of the researchers, in a news release. "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."
The findings are published in the journal Nature.
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