Most processed foods contain added emulsifiers.
These additives are used to modify product texture, prevent ingredient separation, and extend shelf life.
Two of the most common emulsifiers are polysorbate 80 and CMC (the acronym for carboxymethylcellulsose).
Polysorbates – numbered 80, 60, or 65 – are used in baked goods, frozen desserts, and imitation creamers.
CMC is used in ice cream, beer, pie fillings and jellies, cake icings, and diet foods … and it's sometimes counted (legally but dubiously) as part of the "dietary fiber” listed on food labels.
Now, a study suggests that they trigger inflammation and promote disease by altering your gut microbiota and allowing ingested bacteria to leak into your bloodstream.
(The human gut microbiota consists of about 100 trillion bacteria that exert strong influences on many aspects of health.)
Intestinal inflammation promotes two increasingly common problems: inflammatory bowel disease (IBD) and metabolic syndrome (MetS), which promotes diabetes, obesity, and heart disease.
The incidences of both IBD and MetS have risen markedly since the mid-20th century.
And although this correlation doesn't prove a cause-effect relationship, the addition of emulsifiers to processed foods parallels the rise in IBD and MetS.
Gut microbes and disease
Typically, the composition of their gut microbiota is disturbed both in IBD patients and in people with MetS.
Inflammatory bowel disease (IBD) – which includes Crohn's disease and ulcerative colitis – afflicts millions and is often debilitating.
Metabolic syndrome is a cluster of symptoms linked to higher risk for diabetes, cardiovascular disease, and fatty liver disease.
Emulsifiers facilitate the passage of bacteria from the gut to the bloodstream ... probably because they promote two known causes of "leaky gut syndrome":
- Disruption of the GI tract's gut microbiota
- Increased permeability of the intestinal mucosal barrier
Your gut lining normally contains very little bacteria, and it's supposed to prevent the bacteria in food and water from getting into your bloodstream.
Emulsifiers gave mice gut-related inflammation and metabolic problems
Disturbing new research comes from the Georgia State University Institute for Biomedical Sciences.
The authors were Drs. Benoit Chassaing and Andrew Gewirtz, aided by investigators from Emory University, Cornell University, and Israel's Bar-Ilan University (Chassaing B, Gewirtz AT 2015).
Chassaing and Gewirtz thought that, by altering the gut microbiota, emulsifiers might promote inflammation and related diseases, so they designed experiments to test that idea.
The team fed polysorbate 80 and carboxymethylcellulsose to mice, at doses corresponding to the amounts consumed by the average American.
They found that both emulsifiers changed the composition of the rodents' gut microbiota and made it more pro-inflammatory.
Worse yet, the altered microbiota enhanced its capacity to digest and infiltrate the intestine's mucus lining.
These changes triggered chronic colitis in mice genetically prone to this disorder.
And, in mice with normal immune systems, the emulsifiers caused low-grade intestinal inflammation.
The normal mice fed emulsifiers ate more food, became obese, and developed high blood sugar and insulin resistance (which promote diabetes) … key characteristics of metabolic syndrome.
Significantly, these adverse effects of emulsifiers were absent in mice bred to lack a microbiota.
And when the researchers transplanted the microbiota from normal mice to microbiota-free mice, it triggered inflammation and metabolic syndrome.
These outcomes indicate that the changes emulsifiers caused in rodents' gut microbiota explained the additives' adverse health effects.
The study was funded by the National Institutes of Health and the Crohn's & Colitis Foundation of America.
Implications for human health, and better food-additive testing
The team is now testing other emulsifiers in mice, and designing experiments to see how emulsifiers affect humans.
If similar results are seen in people, it would indicate that emulsifiers promote obesity and its consequences, as well as diseases associated with chronic gut inflammation.
Chassaing and Gewirtz's findings suggest that emulsifiers yield adverse effects on the gut microbiota, and a consequent rise in the risk of inflammation-related diseases.
"A key feature of these modern plagues [of inflammation-related diseases] is alteration of the gut microbiota in a manner that promotes inflammation,” Gewirtz said (GSU 2015).
"The dramatic increase in these diseases has occurred despite consistent human genetics, suggesting a pivotal role for an environmental [e.g., dietary] factor,” said Chassaing (GSU 2015).
The good news is that – by improving the gut microbiota – whole-food diets and certain probiotic and prebiotic foods or supplements may help prevent, reduce, or reverse obesity, metabolic problems, and inflammation-related diseases (Delzenne NM et al. 2011; Xiao S et al. 2014).
The Georgia State University researchers also noted that current food additive safety tests wouldn't detect chemicals that promote inflammation and related diseases, or additives that would cause disease in susceptible people.
For example, recent research found that – by altering gut microbiota – artificial sweeteners trigger pre-diabetic glucose intolerance in mice and people alike (Suez J et al. 2014; Suez J et al. 2015).
The troubling outcomes of the new study provide another good reason to avoid processed foods, and to look for emulsifiers on food labels.
- Blaut M, Klaus S. Intestinal microbiota and obesity. Handb Exp Pharmacol. 2012;(209):251-73. doi: 10.1007/978-3-642-24716-3_11. Review.
- Chassaing B, Gewirtz AT. Gut microbiota, low-grade inflammation, and metabolic syndrome. Toxicol Pathol. 2014 Jan;42(1):49-53. doi: 10.1177/0192623313508481. Epub 2013 Nov 27.
- 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. doi: 10.1038/nature14232. Epub 2015 Feb 25.
- Delzenne NM, Neyrinck AM, Cani PD. Modulation of the gut microbiota by nutrients with prebiotic properties: consequences for host health in the context of obesity and metabolic syndrome. Microb Cell Fact. 2011 Aug 30;10 Suppl 1:S10. doi: 10.1186/1475-2859-10-S1-S10. Epub 2011 Aug 30. Review.
- Feehley T, Nagler CR. Health: The weighty costs of non-caloric sweeteners. Nature. 2014 Oct 9;514(7521):176-7. doi: 10.1038/nature13752. Epub 2014 Sep 17.
- Georgia State University (GSU). Widely used food additive promotes colitis, obesity and metabolic syndrome, research shows. February 25, 2015. Accessed at http://www.eurekalert.org/pub_releases/2015-02/gsu-wuf022315.php
- Geurts L, Neyrinck AM, Delzenne NM, Knauf C, Cani PD. Gut microbiota controls adipose tissue expansion, gut barrier and glucose metabolism: novel insights into molecular targets and interventions using prebiotics. Benef Microbes. 2014 Mar;5(1):3-17. doi: 10.3920/BM2012.0065. Review.
- Murphy EF, Cotter PD, Hogan A, O'Sullivan O, Joyce A, Fouhy F, Clarke SF, Marques TM, O'Toole PW, Stanton C, Quigley EM, Daly C, Ross PR, O'Doherty RM, Shanahan F. Divergent metabolic outcomes arising from targeted manipulation of the gut microbiota in diet-induced obesity. Gut. 2013 Feb;62(2):220-6. doi: 10.1136/gutjnl-2011-300705. Epub 2012 Feb 16. Erratum in: Gut. 2013 Feb;62(2):226.
- Sanz Y, Santacruz A, Gauffin P. Gut microbiota in obesity and metabolic disorders. Proc Nutr Soc. 2010 Aug;69(3):434-41. doi: 10.1017/S0029665110001813. Epub 2010 Jun 14.
- Shen J, Obin MS, Zhao L. The gut microbiota, obesity and insulin resistance. Mol Aspects Med. 2013 Feb;34(1):39-58. doi: 10.1016/j.mam.2012.11.001. Epub 2012 Nov 16. Review.
- Suez J, Korem T, Zeevi D, Zilberman-Schapira G, Thaiss CA, Maza O, Israeli D, Zmora N, Gilad S, Weinberger A, Kuperman Y, Harmelin A, Kolodkin-Gal I, Shapiro H, Halpern Z, Segal E, Elinav E. Artificial sweeteners induce glucose intolerance by altering the gut microbiota. Nature. 2014 Oct 9;514(7521):181-6. doi: 10.1038/nature13793. Epub 2014 Sep 17.
- Tilg H. Obesity, metabolic syndrome, and microbiota: multiple interactions. J Clin Gastroenterol. 2010 Sep;44 Suppl 1:S16-8. doi: 10.1097/MCG.0b013e3181dd8b64.
- Xiao S, Fei N, Pang X, Shen J, Wang L, Zhang B, Zhang M, Zhang X, Zhang C, Li M, Sun L, Xue Z, Wang J, Feng J, Yan F, Zhao N, Liu J, Long W, Zhao L. A gut microbiota-targeted dietary intervention for amelioration of chronic inflammation underlying metabolic syndrome. FEMS Microbiol Ecol. 2014 Feb;87(2):357-67. doi: 10.1111/1574-6941.12228. Epub 2013 Oct 21.