Nutritionists have claimed it is ‘far too early’ to advise avoiding emulsifiers – found in food products such as ice cream and chocolate.
The additives – found naturally in some foods, such as eggs – extend the shelf life of products, as well as making them tastier and giving them a smooth texture.
Studies have given them a bad rap, suggesting they are contributing to soaring rates of bowel cancer, obesity and other inflammatory diseases.
However, two experts have hit back at the fears, saying the existing research is too weak suggest emulsifiers – a type of E number – may pose a danger to humans.
Nutritionists say it is ‘far too early’ to advise avoiding emulsifiers – found in ice cream
Nutritionists Dominic Partridge and Alex Johnstone, from the University of Aberdeen, made the argument in The Conversation.
They wrote: ‘Although there is evidence suggesting processed foods and emulsifier-rich foods are bad for you, it still far too early to say we should stop eating them.
‘Particularly as processed foods can play a vital role in our enjoyment of eating – and what is life without that.’
The pair told how they are conducting a study into the exact effects of emulsifiers on human health. So far, evidence has been limited to animal research.
For example, a study on mice, published in the journal Nature, revealed that eating emulsifiers can harm the gut microbiome.
Two common emulsifiers were given to lab mice in drinking water and food, and the mice showed a change in the species of bacteria growing in their gut.
They had lower levels of ‘good bacteria’, and increased levels of bacteria that cause inflammation – compared to the mice who were not fed emulsifiers.
This inflammation led to the mice eating more, gaining weight – particularly body fat – and having higher blood sugar levels.
The symptoms resemble a condition which is growing in prevalence among humans, called metabolic syndrome.
The syndrome – a combination of obesity, high blood pressure and diabetes – which increases the risk of chronic diseases such as heart disease.
Further experiments showed the mice were more prone to the inflammatory bowel disease colitis.
Dr Patridge and Dr Johnstone said the change in gut bacteria could lead to leaky gut syndrome.
This is where the lining the gut is damaged and bacteria from food ‘leaks’ through the intestines into the blood stream.
They added: ‘When this happens, the body responds with an inflammatory response to beat the invading bacteria.
‘This inflammatory response can disrupt the body’s ability to handle glucose and may be a small contributing factor in the development of diabetes and obesity.’
However, writing in The Conversation the pair added: ‘But so far this has only been in mice and cell models.’
Scientists have also found, in mice, the inflammation caused by bad gut bacteria encouraged the development of tumours.
Regularly eating emulsifiers made a ‘favourable’ environment for bowel cancer, the team at Georgia State University wrote in the journal Cancer Research.
However it’s a large leap to apply the findings to humans, experts said.
While mice are unlikely to have emulsifiers in their natural diet, humans probably have for thousands of years.
Emulsifiers are used to blend ingredients together and thicken them, such as sauces and margarine.
But they are in some natural sources. Eggs contain an emulsifier known as lecithin, meaning they are also in mayonnaise.
A single egg yolk contains 1.5g of lecithin, and daily intake of lecithin from food sources can be up to 6g in a Western diet.
Lecithin is present in all plant and animal cell walls, and is often sourced from soybeans to use as an additive.
Studies in humans have found that lecithin may play a positive role in health, by lowering blood cholesterol and blood pressure.
Dr Patridge and Dr Johnstone said there haven’t been many human studies looking into the harmful effects of digesting it.
They wrote: ‘We are testing a diet low in emulsifiers against a high emulsifier diet, with our kitchen providing all the foods in a controlled manner.’
Researchers take blood samples from volunteers and look at how the body is using glucose and how the level of cholesterol.
They are also using faeces samples to look at the composition of the bacteria in the gut.
Dr Patridge and Dr Johnstone said: ‘These outcomes will help us to understand what impact – if any – lecithin has on human health.’