If you’ve ever picked up a packet of food at the supermarket and come across a dizzying array of numbered ingredients written on the back, the odds are that one of them was probably an emulsifier.

Emulsifiers are extremely common in manufactured, processed food. If you have even a passing interest in gut health, you’ll most likely have come across the term ultra-processed foods, or UPFs. As we learn more about how the gut microbiome impacts multiple areas of the body, we’re becoming ever aware of how diets high in UPFs, ie foods that are industrially produced using complex processes and additives, and are potentially contributing to a whole range of health problems including diabetes and heart disease. 

More and more research is now singling out emulsifiers and looking at the impact they could have on our gut microbiomes. So what are emulsifiers and do we need to start avoiding them for the sake of our gut health? 

Emulsifiers are one of the most common ingredients found in UPFs. Their role is to enhance the texture, appearance and shelf life of much of the food we find on the supermarket shelves by combining substances into creamy emulsions. Most of them look like e-numbers written in the ingredients lists on food items.

“Emulsifiers are additives that help two liquids that don’t normally combine together, to combine,” Sophie Medlin, director and specialist dietitian at CityDietitians, tells Stylist. “A good example is the added oil in plant milk, which gives it the right mouth feel. This would rise to the top and split if there were no emulsifiers present.”

As well as plant milk, you’ll find emulsifiers in a whole range of everyday processed food products, including some mayonnaises, sauces, protein powders, baked goods, ice creams, chocolate and salad dressings. 

We’re only beginning to understand the role that emulsifiers might play in gut health and digestion, but research is beginning to emerge which suggests a link between those e-numbers and inflammation.

A 2021 study published in the Microbiome journal looking into the impact of food emulsifiers on metabolic syndrome, concluded that “numerous, but not all, commonly used emulsifiers can directly alter gut microbiota in a manner expected to promote intestinal inflammation”. However, it suggested that more clinical trials are needed to differentiate between ‘detrimental’ emulsifying agents and those with no or low impact on the microbiota.

A further study published in the Foods journal in 2022 also found that “certain emulsifiers could contribute to developing metabolic and inflammatory diseases through the modulation of the gut microbiota”. But, it also suggested that more studies were needed to conclude whether there may be emulsifiers that have “prebiotics effects […] improving and preventing gut disorders”.

Speaking to the Zoe podcast, nutritionist and professor Dr Federica Amati explained: “The gut microbiome has layers. Our gut microbes make things like short-chain fatty acids, which are fatty, but then we also have a water-loving layer in the gut. So you can imagine how if we eat a lot of these emulsifiers it kind of messes up that balance and that separation of the fatty layer and water layer that we want to maintain.”

Early research suggests that some emulsifiers may cause unfavourable changes to the microbiome and disrupt the lining of the bowel wall, potentially leading to inflammation and gut problems. However, Medlin explains: “It’s really important to state that most of this work has been done in rodent and cell models at this stage and larger human trials are still ongoing to establish the impact on human health.”

As research progresses some emulsifiers may be found to be less harmful than others. “Potentially naturally occurring emulsifiers like lecithin, found in egg yolks, may have some benefits,” says Medlin. “But, overall at this stage, we don’t have any suggestion that any of them are good for our gut health.” 

There’s still no definitive answer as to whether we should avoid emulsifiers completely. However, emerging evidence suggests that if you’re prone to poor gut health, it might be a good idea to limit or at least be aware of the kinds of ingredients you’re consuming on a regular basis.

“My advice to patients is that if they have an existing condition affecting the lining of the gut, such as coeliac disease, crohn’s or colitis, being careful with emulsifiers is a good idea on balance,” says Medlin.

If you consume emulsifiers daily, as part of a protein powder for example, it might be worth thinking about switching to a variety without e-numbers. However, as the evidence about the effects of emulsifiers on the gut is so scarce, the best advice is to try and limit your intake of processed foods as much as possible rather than singling out one ingredient. 

Images: Getty