This is because emulsifiers are extremely useful. “They can be used for bread, chocolate, cakes, ice-cream, margarine and processed meats,” says food scientist Natalie Alibrandi, founder and CEO of Nali Consulting. They help products stay smooth and uniform in texture, and stop ingredients separating.
“An emulsifier is used to combine water and oil,” says Alibrandi. “It is structured with a hydrophobic side, which does not like water, and a hydrophilic side, which does like water. So one side is helping bind to the oil or the fat in the product, and the other side is helping bind to the water.”
The ingredients list for Kingsmill’s Mighty White bread includes emulsifiers E471 (Mono- and diglycerides of fatty acids), E472e (diacetyl tartaric acid ester of mono- and diglycerides or DATEM) and E481, (sodium stearoyl lactylate or SSL).
For bread, cakes and pastries, says Alibrandi, as well as helping keep the product consistent wherever it’s made, “they can help increase the shelf life, and make it softer, with less drying effects”. But particularly in baked goods with different components, from sponge and fillings to icings and chocolate drops on top, the various emulsifiers in the product can soon add up.
Emulsifiers are used in chocolate to delay the appearance of a white bloom that can happen if the sugar or fat rise to the surface. “With ice-cream,” says Alibrandi, “it’s so important to have the right amount of fat and air to create the ice structure [texture]. By adding an emulsifier, you’re helping combine the fat and water to create that structure. The same would go for margarine.”
Some brands, she says, are eschewing additives, with slogans like “separation is natural”. She gives the example of certain plant-based milk products. The downside for the consumer, she says, “is that when they add their non-dairy milk to their coffee, it separates. It doesn’t look good, it doesn’t taste good, it’s got a different texture. Whereas by adding emulsifiers, you can help make the product look and taste smooth.”
Alibrandi is comfortable eating them, noting that they’ve been used for more than 50 years in the industry and have long been deemed safe by the appropriate bodies. “Emulsifiers are ubiquitous,” she says. “They are in everything within the food and beverage industry, and we wouldn’t have the convenience and shelf life of products that we do without having these types of ingredients.”
The trouble is, says Megan Rossi, research fellow at King’s College London and founder of The Gut Health Clinic, that the original food safety assessments were done before we knew much about the gut microbiome. She, and the other researchers who have turned their spotlight on emulsifiers, are primarily trying to help those with inflammatory bowel disease – incidences of which have steadily increased since food became industrialised. It is now rising in economically developing countries.
“We’ve known for a long time that people who eat a more ultra-processed diet seem to be at higher risk,” says Rossi, “which we’ve been trying to get our heads around for decades. Inflammatory bowel disease affects one in 200 people. So it’s really quite common and there’s not really a cure for it at the moment.”
There are many elements in an ultra-processed diet that could play havoc with the gut microbiome, but in terms of emulsifiers, says Rossi, “if you think about how they combine water and oil together and turn into this kind of soap [emulsifiers are also used in detergents], we think that may make the gut lining more vulnerable to penetration of specific inflammatory microorganisms”.
Preliminary research has indicated this could well be the case, and it is this research that is now grabbing headlines. It began in earnest in 2015, says Whelan, when a paper was published by one of their collaborators, Benoit Chassaing at Université Paris Cité. He tested the effects in mice of two common emulsifiers: CMC (carboxymethyl cellulose), and P80 (polysorbate 80).
“He fed them water containing either CMC, P80 or neither,” says Whelan, “and he found that the mice consuming the emulsifiers had dramatic changes to the diversity of their bacteria. They had a reduction in the number of different types of bacteria in the gut. We don’t think that is a good thing to happen to your gut microbiome.” Greater numbers of pro-inflammatory bacteria were present, too, but this wasn’t all.
In the mice that consumed emulsifiers, the mucus wall that protects their guts was much thinner. “The emulsifiers had emulsified the mucus, so some of it had been dissolved away,” says Whelan. “This meant the bacteria were much closer to the lining of the gut. What he also showed was that there was much more ‘leaky gut’ – the passage of bacteria, but also other molecules getting through the lining, causing more inflammation.” It looked as though these emulsifiers could be driving inflammatory disorders of the gut such as Crohn’s disease and ulcerative colitis. But these were mice, not humans.
The next step was to eradicate emulsifiers from people’s diets, and see if this helped ease their inflammatory conditions. This is where Whelan came in. “I spend all my time designing diets that are complex, and trying to work out how we might be able to get people to follow them,” he says.
His team started with a small feasibility study in 2020, in 20 people with Crohn’s disease, to see if they could manage to avoid emulsifiers for two weeks. “We found that compliance was really good,” says Whelan, “and actually, lots of people felt a little bit better. The problem is, you can’t take that as proof that the diet works, because when anybody gets a lot of support, and takes part in a study, they feel a little bit better.” That’s why the big trial they are currently undertaking includes a control group on a placebo.
Meanwhile, US researchers in 2017 had run another small study in which 12 patients with ulcerative colitis, the long-term inflammation of the colon and rectum, cut all emulsifiers from their diets for up to 12 months. Five took a daily capsule containing the emulsifier carrageenan, and the other seven participants took a placebo capsule. Three of the five taking carrageenan relapsed, while none of the placebo group did. The same year, the European Food Safety Authority identified food emulsifiers as an emerging risk.
Whelan’s new clinical trial is placebo-controlled, with 150 people with Crohn’s disease. For eight weeks, half will consume a normal diet, and half will move to a low-emulsifiers diet, to see if that will make their inflammation better. “We’re about two-thirds of the way through,” he says, “and we’re really excited to get more patients, so if you can mention that in the article that would be amazing for us.”