Study Linking Emulsifiers and Obesity Dismissed by IFIC

02 Mar 2015 --- The International Food Information Council has dismissed a recent study, published in Nature, that raises concerns about the impact of emulsifiers on obesity and metabolic disorders. It says the study lacks real world application and needs to be viewed in the proper context.

In addition, the findings do not provide sufficient evidence to show a causal relationship between emulsifiers and metabolic disorders.

The study, funded by the National Institutes of Health and Crohn's & Colitis Foundation of America, was led by Georgia State University Institute for Biomedical Sciences' researchers Drs. Benoit Chassaing and Andrew T. Gewirtz.

It investigates the gut microbiota that are disturbed in IBD and metabolic syndrome and the findings suggest emulsifiers might be partially responsible for this disturbance and the increased incidence of these diseases.

"A key feature of these modern plagues is alteration of the gut microbiota in a manner that promotes inflammation," says Gewirtz.

"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 carboxymethylcellulsose, 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 effects of emulsifier consumption were eliminated in germ-free mice, which lack a microbiota. Transplant of microbiota from emulsifiers-treated mice to germ-free mice was sufficient to transfer some parameters of low-grade inflammation and metabolic syndrome, indicating a central role for the microbiota in mediating the adverse effect of emulsifiers.

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.

While detailed mechanisms underlying the effect of emulsifiers on metabolism remain under study, the team points out that avoiding excess food consumption is of paramount importance.

"We do not disagree with the commonly held assumption that over-eating is a central cause of obesity and metabolic syndrome," Gewirtz says. "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 team notes that the results of their study suggest that current means of testing and approving food additives may not be adequate to prevent use of chemicals that promote diseases driven by low-grade inflammation and/or which will cause disease primarily in susceptible hosts.

The International Food Council found that in this study, mice consumed emulsifiers in amounts much higher than is typically consumed in a balanced diet. The strongest effects were found at levels that would only be attained if a person were to consume an all-ice-cream diet. Such findings are inapplicable to people consuming a balanced diet.

In addition, findings suggesting exacerbated inflammatory bowel disease (IBD) from emulsifier consumption were among mice bred to be susceptible to such disorders, which may have contributed to the results. 

According to Marcia Greenblum, MS, RD, senior director of health and wellness at the International Food Information Council, “Gut microbial patterns are a product of many different influences, only one being diet. In addition, the study was done with mice, and the results may not apply to humans. The results of the study do not warrant avoidance of any products or ingredients at this time.” 

Food ingredients such as emulsifiers have been safely consumed in foods and beverages for decades. Of the emulsifiers studied, carboxymethyl cellulose is Generally Recognized As Safe (GRAS) and polysorbate 80 is an approved food additive in the U.S. Emulsifiers perform many functions in our foods, including providing desirable texture and preventing ingredients in foods from separating. These benefits ensure foods and beverages continue to meet consumer expectations for good-tasting, appealing foods and beverages.