The researchers fed mice with two commonly used food emulsifiers, polysorbate-80 and carboxymethylcellulose, at doses designed to mimic dietary exposure through processed foods. They then examined the effect of the additives on the gut microbiota and on the mice themselves.
They found that the emulsifiers altered the species composition of the gut microbiota, making it more likely to promote inflammation. The modified microbiota was better able to invade and digest the mucus layer that normally protects the cells lining the intestine and also produced more inflammatory compounds that could trigger an immune response.
Chronic colitis was observed in mice genetically prone to the disorder, while resistant mice developed low-level inflammation and metabolic syndrome, characterised by increased food consumption, obesity and insulin resistance. However, exposure to emulsifiers had no effect on germ-free mice, which have no gut microbiota.
Further studies to investigate the effects of emulsifiers on humans are planned, but the authors of this study suspect that the effect of emulsifiers on the gut microbiota may play a role in the development of various IBDs and could also be involved in the excess eating that leads to obesity. They suggest that the testing and approval of food additives should take this link into account.
The study is published in Nature and an abstract can be found here.