A new study suggests that two very common emulsifiers – chemicals that stabilize foods and stop products like mayo from separating – could increase the risk of obesity and irritable bowel syndrome.

Mayo and mustard are among the products which almost always contain emulsifiers. Image via Wiki Commons.

The emulsifiers in question are carboxymethycellulose and polysorbate-80; especially in Europe and North America, they are commonly used in processed foods (mayo, ketchup, numerous sauces, ice cream, gluten-free products, fat-free products and many others) and other common products (toothpaste, detergents etc). The study conducted on mice showed that even in low concentrations, these substances drastically affect the gut bacteria which seems to lead to obesity as well as a number of gut-related problems.

In recent times, numerous studies have shown that gut bacteria is crucial to our well-being; it’s important to our weight, immune system and digestive health… it may even control our mind (seriously). Anything disrupting the activity of the “good bacteria” in the gut has the potential to do massive damage. With this in mind, the scientists who conducted this new study might have found why processed food make us so fat, and why gut conditions like irritable bowel syndrome have increased since the mid-twentieth century, especially in association with processed foods.

Andrew Gewirtz at Georgia State University and his team added the two emulsifiers in varying levels to the drinking water of lab mice. They found that most healthy mice who were given the emulsifiers soon developed metabolic problems and/or became obese. When they fed mice even more emulsifiers, they started to develop inflammatory gut diseases, with the severity of the affection being directly linked to the quantity of ingested emulsifiers. These effects were seen even in mice that consumed the equivalent of just one-tenth of the concentration of the emulsifiers that the FDA permits in food products.

The researchers then wanted to see why this happens, so they tested the gut bacteria of these animals and found that the emulsifiers destroy much of the microbial fauna in the gut (again, this microbial fauna is actually beneficial to the body).

Scientists advise eating less processed foods. Image via Wiki Commons.

This is extremely worrying because it’s not easy to find emulsifier-free foods – products labeled as ‘organic’ are just as likely to contain these substances, as emulsifiers are not generally considered processed (I’m really not sure why though). Gewirtz says that many more human and animal studies need to be completed before regulatory agencies would consider changing how additives are approved – but it seems clear that we need to change the way we approve and the way we eat, especially when it comes to processed foods.

The next step would be to move on to human tests and see how our bodies are reacting to these substances. Over the past 50 years, no study has conclusively found that food additives are toxic in mammals, but then again, no large studies have ever focused on the gut bacteria.

Overall, this paper adds a lot to the idea that processed foods have long-lasting and hard to understand effects on our bodies – effects which aren’t at all positive.

Immunologist Andrew Gewirtz at Georgia State University in Atlanta who was also involved in the study concluded:

“When it comes to people making their own decisions, between our studies and others out there, it’s better to eat less processed food,” he says.

You can read the full scientific paper for free, at Nature.

Enjoyed this article? Join 40,000+ subscribers to the ZME Science newsletter. Subscribe now!