Polysorbate 80 and other common food additives may play a role in causing the increase of obesity and inflammatory diseases, according to a letter published in Nature on Feb 25, 2015.
Emusifiers such as polysorbate 80 are detergent-like molecules that can disrupt the protective mucus barrier of the gut, which prevents gut bacteria from contacting cells of the gut lining. Contact can trigger immune response, and result in chronic inflammation, which is implicated in a large number of diseases with rising incidences: colitis, obesity, metabolic syndrome, Crohn's Disease, IBD.
Science Daily reports:
"The dramatic increase in these diseases has occurred despite consistent human genetics, suggesting a pivotal role for an environmental factor," says 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."
Addition of emulsifiers to food seemed to fit the time frame and had been shown to promote bacterial translocation across epithelial cells. Chassaing and Gewirtz hypothesized that emulsifiers might affect the gut microbiota to promote these inflammatory diseases and designed experiments in mice to test this possibility.
The team fed mice 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 almost all processed foods. They observed that emulsifier consumption changed the species composition of the gut microbiota and did so in a manner that made it more pro-inflammatory. The altered microbiota had enhanced capacity to digest and infiltrate the dense mucus layer that lines the intestine, which is normally, largely devoid of bacteria. Alterations in bacterial species resulted in bacteria expressing more flagellin and lipopolysaccharide, which can activate pro-inflammatory gene expression by the immune system.
Such changes in bacteria triggered chronic colitis in mice genetically prone to this disorder, due to abnormal immune systems. In contrast, in mice with normal immune systems, emulsifiers induced low-grade or mild intestinal inflammation and metabolic syndrome, characterized by increased levels of food consumption, obesity, hyperglycemia and insulin resistance.
...
The team is now testing additional emulsifiers and designing experiments to investigate how emulsifiers affect humans. 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.