In recent times, food additives, particularly emulsifiers, have found themselves under scrutiny. These often-overlooked components are essential in maintaining the creamy texture of ice cream and the smooth consistency of salad dressings. Yet, they have become a focal point of concern due to emerging research linking them to health risks such as type 2 diabetes, heart disease, and even certain cancers.

This raises a pertinent question for consumers: should you reconsider that tub of your beloved chocolate chip ice cream?

Emulsifiers serve a crucial role in combining ingredients that naturally resist mixing, much like oil and water. In the realm of home cooking, eggs whisked into oil to create mayonnaise act as a natural emulsifier. However, in the food manufacturing industry, emulsifiers are employed to prevent separation, enhance texture, and prolong freshness. Unlike the simplicity of a whisked egg, industrial emulsifiers are far more complex.

These additives are prevalent in many ultra-processed foods. Commonly, you’ll find lecithin in products like chocolate and margarine to prevent fat separation. Additionally, monoglycerides and diglycerides of fatty acids, often labeled as E471, are used in bread, cakes, and peanut butter to maintain their soft and smooth qualities.

The crux of the matter lies in the testing of food additives. Although they undergo extensive safety evaluations before approval, these tests are predominantly conducted on animals. Consequently, there remains a significant gap in understanding the long-term effects of these additives on humans, particularly when consumed consistently over extended periods.

The big issue is that, while food additives go through rigorous safety checks before they are approved, these tests are usually animal studies. We know far less about what happens in humans, especially when additives are consumed day after day, over many years.

These animal tests have looked at a range of possible signs of harm – from effects on growth to organ damage and cancer – and haven’t found problems even at very high doses. (The amounts allowed in our food are then set at least 100 times lower than the highest dose that showed no effect.)

But what those checks don’t tell us is what emulsifiers might be doing to the trillions of microbes in our gut. And that’s where scientists are now starting to spot potential problems.

Dr Emily Leeming says the long-term effects of food additives on humans isn’t fully understood due to a lack of research

Ice cream often contains emulsifiers which help it keep its shape – but could they be harmful to our gut health?

Because the gut is so closely linked to the rest of the body, changes there could have knock-on effects elsewhere, from our immune system to metabolism and even our long-term disease risk. For instance, a new study where 60 healthy volunteers first ate an emulsifier-free diet for two weeks, then added daily brownies containing one of five common emulsifiers (or none at all) for a month, found that some emulsifiers caused changes in the gut.

Carboxymethyl cellulose (used in ice cream) and polysorbate-80 (often added to sauces) lowered levels of short-chain fatty acids – the by-products made by our microbes that support gut health and the immune system.

Another common emulsifier carrageenan (found in foods such as flavoured milks and processed meats, including turkey slices) made the gut lining ‘leakier’, meaning unwanted molecules could more easily slip through and – in theory – trigger inflammation (although the study, reported in the journal Clinical Gastroenterology and Hepatology, didn’t find any evidence of this).

Soy lecithin (the most common emulsifier, used in everything from chocolate to margarine) and rice starch (often used as a thickener for sauces and puddings) didn’t cause any obvious problems.

The types most commonly flagged in emerging research for potential health harms – carrageenan, carboxymethyl cellulose and polysorbate-80 – are actually rarely used in the UK food supply.

They are found respectively in only 4.4 per cent, 1.4 per cent and just 0.06 per cent of foods.

In the case of polysorbate-80, that’s only eight foods out of nearly 13,000 supermarket products surveyed by a 2023 study in Public Health Nutrition.

Carrageenan often gets the most attention, mainly because it is confused with degraded carrageenan, a different substance not used in food that’s been shown to cause gut inflammation in animals.

For now, the evidence that emulsifiers cause harm long-term in humans is limited, though we have only a handful of large studies to draw on.

One study, published in the BMJ in 2023 and based on data from nearly 95,000 adults in France, looked at 37 emulsifiers, but found only a few – celluloses (E460, E466), monoglycerides and diglycerides of fatty acids (E471, E472b, E472c), and trisodium phosphate (E339) – were linked to a potentially harmful effect. The people who ate the most had a 3 to 11 per cent higher risk of heart disease.

Another study by the same group, published last year, found those who ate the most thickeners such as xanthan gum and guar gum – had an 8 to 15 per cent greater risk of developing type 2 diabetes. The researchers suggested these gums may affect the gut and, in turn, how the body handles blood sugar.

This ties in with the ADDapt trial led by King’s College London looking at the impact of cutting out emulsifiers for eight weeks in people with Crohn’s disease, a type of inflammatory bowel disease. Early results, released in January, were striking: almost half of those on a low-emulsifier plan experienced an improvement in their symptoms, compared with less than a third in the group on a matched diet with emulsifiers added back in. While these studies don’t prove cause and effect, they do flag some emulsifiers that deserve to have a closer look.

What does this mean for you now? The overall message is that not all emulsifiers are the same (and many of them you don’t need to worry about).

And the good news is most people aren’t likely to be eating them in large enough amounts for it to be a major concern (so the occasional ice cream is still fine).

A better focus is on what to add in. Eating a diet rich in fruit, vegetables, beans and wholegrains not only supports the gut by providing your gut microbes with its favourite food – fibre – but also naturally leaves less room for ultra-processed foods.

So instead of cutting things out, think about including more whole foods. It’s far simpler than scouring food labels.

Ask Emily

My mum is about to have hip surgery – what should she be eating after the operation?

Food can be a big part of recovery: while it won’t replace rest, physio or medical care, it does give the body the raw materials it needs to heal.

The first priority is protein, as this provides the building blocks for new tissue and helps protect muscle strength, which is important, as your mum is likely to be relying on crutches initially.

Try to include protein in every meal – for example, eggs for breakfast, lentil soup or chicken for lunch, and meat for dinner.

If she’s struggling with her appetite, morning and afternoon high-protein snacks – such as yoghurt with nuts, or cheese and crackers – can help. Dairy foods provide nutrients such as calcium, B vitamins and zinc that support healing.

A review of studies, published in Sports Medicine and Health Science in 2023, found that patients given extra protein after hip or knee surgery lost less muscle and regained function more quickly.

If your mum can’t eat a lot at one meal, a protein drink can be used as a top-up (but just not as a replacement for meals).

Calorie intake is also important – if she eats too little, weight loss is likely to include muscle, which will be vital for getting her back on her feet.

Constipation can be a common side-effect of pain medication, so fibre and fluids are vital. As well as wholegrains, beans and fruit, it’s important after surgery to stay on top of fluid intake (1.5 to two litres a day) to keep the bowels moving.