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Food Additives and Our Microbiome

Emulsifiers may mess with healthy bacteria.

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Junk food with food additives

It can feel like a real gut punch! Just take a peek at the ingredient list of most processed packaged foods including energy bars, nondairy milks and salad dressings, and you’ll almost always see them: food additives like emulsifiers that are used to improve texture and shelf-life.

Many people don’t give them much thought, but in groundbreaking research, a team of scientists say those additives could upset our microbiome. In a randomized controlled-feeding study published in Gastroenterology, the team studied healthy adults who, after the first 3 days, lived at a designated study site for an additional 11 days. Participants consumed either an additive-free diet or an identical diet supplemented with carboxymethylcellulose (CMC), an emulsifier also known as cellulose gum that’s added to a wide range of packaged foods.

CMC consumption changed the make-up of bacteria populating the colon of participants, reducing select beneficial species. Fecal samples from CMC-treated participants showed a large depletion of bacteria-produced metabolites that are thought to help maintain a healthy colon.

Lastly, the researchers noticed that a small subset of subjects who consumed CMC displayed bacteria encroaching into the normally sterile gut mucus layer. They reported that this has previously been observed to be a feature of inflammatory bowel diseases like colitis and colon cancer, as well as type 2 diabetes. This could be a surprising contributing factor as to why high intakes of ultraprocessed foods, which frequently contain emulsifiers, have been shown to raise the risk for poor health.

The research needs to be repeated with other emulsifiers like guar gum and carrageenan to determine if they have the same detrimental impact on the microbiome. Responses may also be highly personalized, with people responding differently to different food additives.

See also: Term of the Day: Ultraprocessed Foods


Matthew Kadey, MS, RD

Matthew Kadey, MS, RD, is a James Beard Award–winning food journalist, dietitian and author of the cookbook Rocket Fuel: Power-Packed Food for Sport + Adventure (VeloPress 2016). He has written for dozens of magazines, including Runner’s World, Men’s Health, Shape, Men’s Fitness and Muscle and Fitness.

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