What do you understand about emulsifiers and how they impact gut health? Dr Linia Patel gives you the lowdown.
From melt-in-your-mouth chocolate to creamy salad dressing to that easy-to-mix protein shake, in the food world emulsifiers play an important role in creating the texture and consistency of many of our favourite foods. They are just one commonly used additive out there. In a previous blog on ultra-processed foods we learnt that, in the UK, approximately 60% of our calories come from ultra-processed foods. While there is a link between ultra-processed food intake and poorer health, we still do not know exactly why. One theory proposed is that the additives (including emulsifiers) may have a negative impact on our gut health. Let’s delve into emulsifiers in a little bit more detail.
What are emulsifiers?
Emulsifiers are extremely useful. They are used in food processing to blend ingredients that wouldn’t naturally mix, such as oil and water. They work by reducing the surface tension between the hydrophobic side, which doesn’t like water, and the hydrophilic side, which does like water, allowing them to form a stale mixture. For example, in salad dressing they ensure that the oil and vinegar stay combined instead of separating. Emulsifiers in ice cream help to prevent the formation of ice crystals, resulting in a smoother and creamier product. They can be found in a wide range of processed foods, including baked foods, dairy products, sauces and spreads. They not only help to improve textures and stabilise mixtures, but they prolong shelf life. In the UK, the Foods Standard Agency (FSA) has approved 63 different types of emulsifiers, stabilisers, gelling agents and thickeners in the food supply. In the United States, the Food and Drug Administration (FDA) has approved 171 emulsifiers and emulsifying salts. Common examples include the following:
- Lecithin (E322)
- Carrageenan (E407)
- Guar gum (E412)
- Xanthan gum (E415)
- Carob bean gum (E410)
- Hydroxypropyl cellulose (E463)
- Polysorbate-80
Potential health impacts
The first thing to highlight is that emulsifiers are generally recognised as safe by regulating agencies like the FDA and the European Food and Safety Association (EFSA); however, there is ongoing research into their potential health impact and, over the last few years, this has turned the spotlight on emulsifiers.
One of the first studies that caught headlines was from the University of Paris Cite. This study tested the effects of two common emulsifiers – CMC (carboxymethyl cellulose) and P80 (polysorbate 80) – on mice. Mice were fed water containing either CMC, P80 or neither. Findings from the study reported that mice consuming either emulsifier had dramatic changes to the diversity of their bacteria in their gut. They not only had higher numbers of pro-inflammatory bacteria but these mice also seemed to have thinner mucus wall linings. While human digestive systems can’t break down emulsifiers, gut bacteria can. The emulsifiers, as a result, can begin to emulsify the mucus, which predisposes the gut to become ‘leakier’. In a healthy gut, a mucous barrier protects the gut’s lining. It stops gut bacteria from reaching the lining and triggering an immune response. A ‘leaky gut’ means that it’s easier for bacteria and for other molecules to get through the lining, which causes more inflammation.
While this research might seem convincing, in the hierarchy of nutritional science, animal studies are pretty low in the ranks. While animal studies can shed a certain amount of light, we can’t extrapolate the finding to humans. Since this study, a human trial by Chassaing et al showed that 15g of CMC over 11 days increased markers of gut inflammation and reduced gut microbiota diversity compared with an additive-free diet. However, caution must be applied when extrapolating this, as in reality actual intakes within the population are much lower – around 4mg/day.
With so much focus on gut health and with an increase in the prevalence of people with inflammatory bowel disease (IBD), scientists are wanting to know why, and some are pointing to emulsifiers. While this is an interesting link, very few studies have looked at the effects of emulsifiers in humans with IBD. Those that exist are very small. For example, one team of researchers in the US ran a small study of 12 patients with ulcerative colitis, the long-term inflammation of the colon and rectum. Five of the patients took a daily capsule containing the emulsifier carrageenan and the other seven participants took a placebo capsule. The results showed that after 12 months, three of the five taking the emulsifiers relapsed, while those taking the placebo capsule didn’t.
Another study recruited 20 participants with Crohn’s disease. Participants followed a low-emulsifier diet for 14 days, after which they reported to have fewer IBD symptoms and more control over white condition.
Emulsifier-free diet for all then?
While all the evidence above seems quite a convincing case, it’s important to interpret the results with caution, as always in nutrition science. There is so much more we need to learn.
There are still gaps in the research. The researchers only investigated one emulsifier at a time for relatively short periods of time. To date, only a few emulsifiers have been studied. In some studies, they were in higher amounts that would normally be consumed. To date, we don’t have a clear-cut picture of the cumulative effects of consuming cocktails of emulsifiers daily over a lifetime in the context of different lifestyles. We need more research.
Take-home message
The reality is that it is nearly impossible to completely avoid emulsifiers and it’s probably not necessary. Emulsifiers play a vital role in the texture and stability of many processed foods. While they are generally considered safe for consumption, we need more research to fully understand the potential health impacts. However, the message that needs to land loud and clear is that in both the UK and USA we overconsume all ultra-processed foods. Now, clumping all foods into one group called ultra-processed is not a correct science, as it is not that clear cut. Within the ultra-processed food groups there are some foods that will be better for you than others. No food should be off the table. However, the more whole food you put on the table, the less ‘junk food’, which is always going to be a good move.
Tips for making healthier choices
- Focus on whole foods. Loading your plate up with a variety of veggies, fruit and plant-based foods, wholegrains, lean protein and healthy fats most of the time is the key.
- Read labels. Take the time to read labels. The fewer the ingredients the better, especially when it comes to habitual intake.
- Serve up home-cooked meals. Cooking meals from scratch allows you to control the ingredients you use. If you are not able to, add in an extra portion of veggies, fruit or herbs to take it up a level in nutrition terms.
- Moderation is key. It’s OK to enjoy your favourite ultra-processed foods occasionally. It’s all about finding your balance.
References
- Pagliai G, Dinu M, Madarena MP, Bonaccio M, Iacoviello L, Sofi F, Consumption of ultra-processed foods and health status: a systematic review and meta-analysis, Br J Nutr.
- Chassaing B et al (2022), Randomized controlled – feeding study of dietary emulsifier carboxymethylcellulose reveals detrimental impacts on the gut microbiota and metabolome, Gastroenterology, 162(3): 743-756.
- Furuhashi H et al (2020), Dietary emulsifier polysorbate-80-indiced small intestinal vulnerability to indomethacin-induced lesions via dysbiosis, Journal of Gastroenterology and Hepatology.
- Bhattacharyya S et al (2017), A randomised trial of the effects of the no-carrageenan diet on ulcerative colitis disease activity, Nutrition and Healthy Aging, 4(2): 181-192.
- Naimi S et al (2021), Direct impact of commonly used dietary emulsifiers on human gut microbiota, Microbiome, 9(66).
- Bancil A et al (2020), Food additive emulsifiers and their impact on gut microbiome, permeability and inflammation, mechanistic insights in inflammatory bowel disease, Journal of Crohn’s and Colitis, 15(6): 1,068-1,079.
- Llewellyn S et al (2018), Interactions between diet and the intestinal microbiota alter intestinal permeability and colitis severity in mice, Gastroenterology, 154(4): 1,037-1,047.
- Cox S et al (2020), Food additive emulsifiers: a review of their role in foods, legislation and classifications, presence if food supply, dietary exposure, and safety assessment, Nutrition Reviews, 78(6): 726-741.
