Some food additives with emulsifying function alter the microbiota, causing colitis, intestinal inflammation and obesity. So concludes the scientific study published in Nature by researchers at four universities, in the US and Israel. (1) After testing the impact on intestinal ‘bacterial flora’ of two widely used emulsifiers, carboxymethyl cellulose (or CMC) and polysorbate-80.
Microbiota, protective functions
The microbiota-that is, the community of microbes living in the gut of humans and animals-has a crucial role in regulating the body’s physiology. (2) In modulating metabolic responses, energy homeostasis (and thus weight control), blood pressure, immune system, etc. It is inherited through the matriarchal line (mother, maternal grandmother, maternal grandmother’s mother, and so on), and is subject to alterations, positive and negative, as early as the pre-natal stage.
External factors-such aspesticide exposure and diet-can significantly affect gut microbial ecology and bacterial metabolites. Its disruption is associated with numerous chronic inflammatory diseases, including inflammatory bowel disease and metabolic syndrome.
The intestinal bacterial population transmits signals to the dense network of neurons that characterize the ‘second brain’ (enteric nervous system, intestines), which in turn interacts continuously with the first brain (central nervous system). Communication occurs through the natural balance of muco-bacterial interactions. That is, the bacteria transfer signals to the epithelial cells of the intestine through multilayered mucus structures that line the intestinal surface.
However, the action of the emulsifiers under consideration-whose molecules are similar to those of detergents-has been shown to alter this delicate mechanism. Causing in guinea pigs disorders and diseases.
Emulsifiers E466, E433 and microbiota disruption. The scientific study
The two emulsifiers covered by the research published in Nature are commonly used by the food industry. In the ingredient list, they are listed on the label as.
– Carboxymethylcellulose, CMC or E466,
– polysorbate-80 or E433.
The researchers gave guinea pigs relatively low concentrations (1 percent for 12 weeks) of the two emulsifiers, in line with current human exposure. (3) And they observed, as an effect, the manifestation of low-grade inflammation, obesity and colitis.
Emulsifier-induced metabolic syndrome is associated with microbiota invasion on intestinal mucus, alteration of its composition, and increased pro-inflammatory potential. Microscopic examination showed a dramatic reduction in mucus thickness, to the point of approximating physical contact between bacteria and epithelial cells. And the microbiota was found to be ‘aged’ and altered.
Harmful effects with minimal doses
The widespread use of emulsifiers in foods-and the resulting cumulative effect-suggests that it is easy to exceed the 1 percent daily threshold examined by the study. But harmful effects occur even at lower doses.
Already a 0.1% concentration of the two emulsifiers produces inflammation and low-grade metabolic syndrome. In detail,
– for CMC, 0.1% resulted in modest increases in body weight and fasting blood glucose, while 0.5% produced obvious signs of low-grade inflammation (shortened colon, enlarged spleen) and increased adiposity,
– for P80, 0.1% caused low-grade inflammation and increased adiposity, while 0.5% caused mild dysglycemia.
Additives approved with insufficient studies
The last half century has seen a steady increase in the use of food additives, many of which have been approved but not thoroughly tested, the researchers note. Tests on food additives, moreover, are performed only to detect acute toxicity and/or carcinogenicity.
In the case of the emulsifiers under consideration, for example, scientific research has now revealed a different-and equally dangerous-offensive scope of the molecules. Which disrupt the host-microbiota relationship, with alterations such that the microbiota is attributed with increased mucolytic and pro-inflammatory activity, causing intestinal inflammation.
Disturbing the researchers’ conclusion.‘Our observations in mice suggest the possibility that dietary emulsifiers may have contributed to the increased incidence of IBD (Inflammatory bowel disease) and metabolic syndrome after the mid-20th century, and perhaps other chronic inflammatory diseases.’
Marta Strinati and Dario Dongo
Notes
(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. doi: 10.1038/nature14232. Epub 2015 Feb 25
(2) Paola Palestini and Dario Dongo. (2019). Microbiome and gut, the second brain, GIFT(Great Italian Food Trade), 2/14/19, at https://www.greatitalianfoodtrade.it/salute/microbioma-e-intestino-il-secondo-cervello
(3) In the U.S., P80 has been studied for toxicity and carcinogenic potential and is approved by the U.S. Food and Drug Administration (FDA) for food use up to a concentration of 1%. CMC, on the other hand, has not been studied extensively but is ‘generally considered safe (GRAS)’ and used in various foods up to 2%
Professional journalist since January 1995, he has worked for newspapers (Il Messaggero, Paese Sera, La Stampa) and periodicals (NumeroUno, Il Salvagente). She is the author of journalistic surveys on food, she has published the book "Reading labels to know what we eat".
Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.
