Emulsifiers in processed food and your health

A recently published paper in the journal Nature (1) suggests that the emulsifiers added to many processed foods can lead to inflammation of the large bowel and to obesity and related diseases such as diabetes. The paper is an account of a research study in which groups of mice were fed one of two common synthetic emulsifiers (carboxymethylcullulose and polysorbate-80) in their drinking water for 12 weeks and then compared with genetically similar mice who over the same time period had been given an identical diet but without the added emulsifiers. The mice who ingested emulsifiers had a profound change in the composition and in the distribution of intestinal bacteria (gut microbiota): (i) there were fewer bacterial species overall and a reduction in the numbers of bacterial species commonly associated with good health, and (ii) the distance between the bacteria and the cells lining the bowel, normally covered by a layer of protective mucus, was reduced by 50%. Associated with these changes in the gut microbiota, the emulsifier-treated mice had a higher prevalence of inflammation of the large bowel and of obesity, an increased fasting blood glucose, and an abnormal response to large doses of glucose similar to that found in diabetes. Transfer of the gut microbiota (through fecal transplant) from the emulsifier-treated mice to a group of non-treated mice led to the development of bowel inflammation and obesity in the transplanted group indicating that changes in the microbiome were necessary and sufficient for all the other effects that were observed. The authors of the study suggest that the harmful effect of the emulsifiers was through disrupting the thick layer of mucus that lines the intestine and protects it from intestinal bacteria; damage to the mucus layer would reduce its protective effect making chronic inflammation and associated abnormalities (obesity, diabetes) more likely.

Emulsifiers are used to bind different liquids together (e.g. oil and water) that under normal circumstances would remain separate. Creating an emulsion is a crucial step in the production of many processed foods, and as a consequence, emulsifiers are ubiquitous in the processed food industry that uses 400,000 metric tonnes of synthetic emulsifiers each year in products ranging from ice cream, baked goods, and processed meats to chewing gum. The results of this study discussed above are not comforting to those for whom processed food is a major component of their diet. It is not known how the findings in this study relate to human obesity, dietary choices, and the practices of the food processing industry. However, the results are consistent with the growing conviction that the gut microbiota has an important role in human matabolism, nutrition, and immunity. It is possible that change in gut microbiota that result from changes in diet, particularly the additives in processed food, is a significant contributor to the epidemic of obesity in the United States and in other economically advanced countries.

(1) Chassaing B, Koren O, Goodrich JK, Poole AC, Srinivasan S, Ley RE, Gewirtz AT.Dietary emulsifiers impact the mouse gut microbiota promoting colitis and metabolic syndrome. Nature. 2015 Mar 5;519(7541):92-6