Emulsifiers are one key group of food ingredients that is broadly used in formulation of packaged food products. Scientists have shown that it may cause disruption of the mucosal layer in our intestines and thus promote diseases related to gut inflammation. This research, led by scientists at Georgia State University, was initiated with the hypothesis that “emulsifiers, detergent –like molecules” may disrupt mucus-bacterial interaction, increase gut permeability and consequently lead to inflammatory bowel disease (IBD) as well as obesity related disorders. The key findings of this research:
Mice fed a diet containing the aforementioned food ingredients showed a reduction in the biodiversity of microbiota and specifically an increase in the bacteria group of Bactreroidales known to be linked to health issues. 
These food ingredients caused an increase in gut permeability and inflammation.
Mice fed with the ingredients showed a “modest” weight gain and increase in fat mass. 
In genetically modified mice that were susceptible to colitis, the food ingredients induce the disease.
The two food ingredients that were tested are polysorbate-80 (PS-80) and carboxymethyl cellulose (CMC). It is not clear why the researchers chose these specific “emulsifiers”. While PS-80 is an emulsifier, CMC is not. It is employed in food formulation to modify viscosity thus it stabilizes emulsions. Furthermore, the fatty acid moiety of PS-80 is 100% hydrolyzed by pancreatic lipase in the small intestines and therefore only polyethylene sorbitan enters the colon, a compound that doesn’t have emulsification properties. In other words, the effect of these compounds has nothing to do with emulsification but probably by direct effect on the microbiota. mouse_manMice and rats are the experimental tool in the initial phases of clinical research. However, data generated from a mice study may be misleading and extrapolation to human may be incorrect. A case in point is the saccharin safety study in the 1970s. Studies in rats linked saccharin to the development of bladder cancer. Based on this study, the FDA required a warning label on all food products containing saccharin. Further studies demonstrated that the initial results apply only to rats and not to humans. Based on this data, saccharin was delisted in 2000 from the list of potential carcinogens. When mice are compared genetically to men, only about 300 genes are unique to one or the other. But in some research areas we need to be mindful of the key differences. As for digestive track research, mice are coprophagic (eat their own feces) and have an order of magnitude larger extent of “leaky gut”. Mice state of health appears to be much more dependent on their microbiota than humans.

Human Microbiota is an emerging area of research.

This is the second study that links food ingredients to health issues related to disruption of the microbiota homeostasis. The previous study demonstrated that artificial sweeteners might cause glucose intolerance and lead to type-2 diabetes. These two research programs focused on five food additives (CMC, PS-80, saccharin, sucralose, aspartame). All five compounds are synthetic products or derived through chemical modification of natural products. Does it mean that synthetic food additives are bad for you and natural compounds are safe? If you follow the action and announcements of the food industry it seems this is really the case. For example, Nestle and Hershey recently announced the removal of artificial ingredients from their candies in the US. The scientists of Georgia State University call for a revision of the safety evaluation and the approval process of new food ingredients. But in order to include the human microbiome as part of the safety protocol, more research data is required – of mice and men. References Benoit Chassaing et. al “Dietary Emulsifiers impact the mouse gut microbiota promoting colitis and metabolic syndrome”Nature, 2015, DOI: 10.1038/nature 14232 Image credit: ‪drugdiscoveryopinion.com