Tim Spector's ZOE pinpoints the most harmful additive in processed foods - amid claims the ingredient is behind shocking rise in young bowel cancers

• READ MORE:  The ultra-processed diet that experts believe gives you cancer

A top nutritionist has revealed a food additive found in everything from cakes, to mayonnaise and even sausages, has been linked to gut problems — including bowel cancer. 

Speaking on diet guru Tim Spector's ZOE podcast, Dr Federica Amati, a researcher at King’s College London, said emulsifiers listed on the back of the packet are a 'red flag'.

These are mixed into food to help bind fats and water, helping enhance the texture, appearance and shelf-life of food. 

But according to Dr Amati, they have been shown to break down the protective layer of mucus that lines the gut, allowing an influx of harmful bacteria to seep in.

This triggers and imbalance of gut microbiomes and inflammation, she added.

This inflammation, a raft of alarming studies now suggest, is a trigger for irritable bowel syndrome and inflammatory bowel diseases such as Crohn's and colitis. 

And emerging evidence now links emulsifiers to increases in bowel cancer diagnoses, particularly in younger people. 

Emulsifiers are found in ultra-processed foods, or UPFs, that now make up 57 per cent of the average UK diet.

Simple processed foods include tinned, cooked vegetables and fish, such as tuna and daily products like cheese.

These contain little more than the main ingredient and water, oil or one of two extra ingredients — you could potentially make them yourself. 

UPFs, however, are highly processed, involving factory techniques, and contain additives — of which emulsifiers are just one.

An easy sign a food could be a UPF is if it contains ingredients you wouldn't find in your kitchen cupboard, say critics of the products.

Emulsifiers combine substances or liquids into creamy emulsions, they also help foods feel smoother and less sticky when you eat them, explains Dr Amati.

She said: 'Let's say you've picked up a sandwich. The filling might contain an emulsifier called guar gum. A sandwich spread could have [one] called xanthan gum in it. 

'Or you might pop some cereal in your basket and that might have stearoyl lactylates. Even the bar of chocolate you threw in at the till, that likely contains lecithin [which is an emulsifier].'

While in the US 171 emulsifiers have been approved for human consumption, only 63 have been approved in the UK. This includes other agents like stabilizers, gelling gels, gelling agents, and thickeners.

Typically, emulsifiers are made from plant, animal-based sources or synthetic chemicals.

For example lecithin, found in chocolate, can be sourced from soybeans or eggs, liver, peanuts, and wheat germ.

Xantham gum is a synthetic emulsifier made by bacterial fermentation. Microbes break down glucose and make xantham gum as a byproduct.

The emulsifiers used in bread include diacetyl tartaric acid esters and mono and diglycerides of fatty acids. These create a softer loaf that lasts longer, Dr Amati explains. 

She said that emulsifiers are often added to yoghurt to prevent it from developing a watery layer on top. 

'There's no reason why they shouldn't separate. It's just purely aesthetic, and because we're used to having this consistent creaminess in our products,' Dr Amati said. 

Manufacturers are not required to record the amount of emulsifiers in each individual food item. That means we never truly know how much we are consuming. 

Dr Amati highlighted that one study looked at the intake of some additives, including emulsifiers, in the UK, Ireland and France and found children and adults did exceed the acceptable daily intake of some emulsifiers, which could be very harmful.

Explaining the damage emulsifiers may cause the gut, Dr Amati the gut 'biome' is made up of layers of fats and water.  

'If we eat a lot of emulsifiers [which bind water and fat] it kind of messes up that balance, that separation of fatty layer and water layer, which we actually want to maintain in the gut microbiome.'

This, it has been theorised, breaks down the stomach lining, leading to bacterial infections.  

'We think that this process could be linked to bowel cancer,' explained microbiome scientist and gut specialist Dr Alasdair Scott, speaking to The Mail on Sunday earlier this month. 

'Studies done on animals that confirm this, but not yet on people — in humans it can be much more difficult to prove why exactly a tumour has formed.' 

Experts have warned bowel cancer is hitting more and more young people, with diets full of UPFs thought to be a possible cause. 

Incidences of the disease, which kills 17,000 per year in the UK, have risen by 22 per cent in the under 50s over the course of the last 30 years.   

Consuming the additive also seems to have a 'negative impact on our health overall,' warns Dr Amati.

Other research has linked emulsifiers in the diet to a higher risk of cardiovascular disease.  

At present most of the studies on emulsifiers in the gut have been done on animals, so experts warn we can't assume the effects are the same on humans.

These typically study one emulsifier at a time so the effects of consuming a 'cocktail' of them at once, which is how many of us will eat them, is unknown, Dr Amati adds.

A small trial in 2017 looked at the effect of the emulsifier carrageenan on patients with ulcerative colitis — a type of inflammatory bowel disease that causes abdominal pain and digestive issues.

Results suggested consuming it increased the likelihood of symptoms.

Another study involved giving Crohn's patients a low emulsifier diet and found they had fewer symptoms.

Both Crohn's disease and ulceritis colitis cases, of which cases have risen in recent years, increase the risk of colorectal cancer by causing chronic inflammation in the colon.

Dr Amati said seeing emulsifiers in an ingredients list should be 'a red flag', adding: 'If a food contains emulsifiers, artificial sweeteners, and there's lots of ingredients that you just wouldn't have in your kitchen, then think about whether you could replace it with something else in your shopping basket.'