Emulsifiers – are they the enemy?

You can spot an emulsifier by reading the ingredients list on food products. In the UK, emulsifiers can also be listed as E numbers. The full list of approved emulsifiers by the Food Standards agency can be found here.

We will discuss some of the most commonly used emulsifiers in foods and what the data says (so far) on whether they are safe or potentially detrimental to the gut.

Lecithin

Lecithins (E322) are composed of choline and fatty acids. They are naturally found in milk, eggs and plants including rapeseed, sunflower and soy.

Soy lecithin has been shown to be beneficial to cardiovascular health, such as lowering LDL cholesterol and blood lipids (1).

There are very limited studies on the effects of lecithins on the gut microbiota, particularly in humans. In animals, both rapeseed and soy lecithin consumption lead to an increase in bacteria belonging to the C. leptum group (2). These bacteria produce butyrate, a short-chain fatty acid that is important for gut health. Therefore, lecithins may be somewhat beneficial.

Verdict: Safe

Gums

Gums are polysaccharides (long chain carbohydrates). They typically come from plants or from the bacterial breakdown of substances. These include guar gum, acacia gum (aka gum arabic), xanthan gum, cassia gum, and locust bean gum.

Guar gum (E412): shown to reduce total cholesterol and LDL cholesterol (3). Has positive effects on the gut microbiota in humans (4).

Acacia gum / gum Arabic (E414): appears to promote the growth of beneficial Bifido-bacteria in animals and humans (5,6)

Xanthan gum (E415): may promote the growth of Ruminococcaceae bacteria that produce short-chain acids (7). These are important for gut health, especially butyrate.

Cassia gum (E427): shown to have positive effects on the gut lining and gut microbiota in animals (8,9).

Locust bean gum (E410): helped to reduce intestinal inflammation in mice and increase levels of beneficial bacteria in mice (10).

Verdict: Safe

Carrageenan

Carrageenans (E407) are an extract from various species of red seaweed including the popular Irish sea moss. They act as thickeners and can be found in some dairy products and plant-milk alternatives.

Animal studies have shown a potential link between carrageenans and inflammation in the gut suggesting that carrageenan may precipitate the development of inflammatory bowel disease, specifically ulcerative colitis.

However, an important thing to note is that carrageenan can be chemically converted into degraded carrageenan, aka poligeenan. This is purposefully used to cause inflammation animal studies, but it is often misinterpreted for food grade carrageenan. It is not possible for carrageenan to be converted into degraded carrageenan by the human body (11).

To date, there is a lack of data to show that carrageenan causes intestinal inflammation. A small study showed that 7 days of eating foods that contain carrageenan did not increase inflammation or symptoms in people with ulcerative colitis (12).

On the other hand, a separate small study found that 3 out of 5 participants experienced a relapse (i.e. a flare up) of ulcerative colitis after taking carrageenan capsules for 5 weeks or longer, whereas 0 out of 7 participants in the placebo group relapsed (13). However, this study looked at carrageenan capsules whereas carrageenan added to foods often binds to proteins may have induce a different physiological response. Therefore, it does not represent the way most people would consume carrageenan in their diet.

To our knowledge, there are no trials in humans without inflammatory bowel disease to show that carrageenan induces intestinal inflammation. In fact, one trial found that a carrageenan supplement lowered some markers of inflammation reduced blood cholesterol and lipids in humans (14).

Ultimately, there is no convincing evidence to show that carrageenan causes intestinal inflammation in humans at the levels found in foods. Degraded carrageenan or poligeenan appears to cause intestinal inflammation in animals but this is not the same as food grade carrageenan.

Verdict – Probably safe

Cellulose and cellulose derivatives

Cellulose (E460) is the main component in plant walls which humans cannot digest. It is used in foods to prevent clumping, such as in some shredded cheeses.

Cellulose can also be synthetically modified into other useful emulsifiers including methyl cellulose (E461), hydroxypropyl cellulose (E463), and carboxy methyl cellulose (E466).

There are many animal studies showing that cellulose and its derivates are safe and act like insoluble fibre. However, carboxy methyl cellulose (E466) was shown to causes changes to the gut microbiota that promoted intestinal inflammation in mice (15). These findings were recently replicated in a human trial.

In the trial, 16 participants were put on an emulsifier-free diet (16). One group of 7 participants were then randomized to be given 15g of carboxy methyl cellulose with their food whereas the other group of 9 participants were randomized to receive 0g. Those receiving the emulsifier reported more abdominal discomfort and experienced a loss of gut microbial diversity and 2 participants showed signs of gut inflammation.

15g of carboxy methyl cellulose is quite a lot. For example, the amount of carboxymethyl cellulose used in foods is typically around 1% or less, so a 100g serving would contain around 1g. A meta-analysis found that higher consumption of carboxy methyl cellulose was linked with a greater risk of cardiovascular disease and coronary heart disease (17). Therefore, if you find that you are consuming foods containing this emulsifier every day, then perhaps switch to alternatives.

Verdict: Limit

Polysorbates

Polysorbates are emulsifiers used mostly in pharmaceutical drugs and skin care products, but they can also be added to some foods, such as vegetable shortening, margarine, and baked goods. They can be identified from the E numbers E432–E436.

A study in mice showed that relatively low concentrations of Polysorbate 80 (E433) lead to changes in the gut microbiota and gut barrier that may promote intestinal inflammation, weight gain and metabolic disorders (15).

To our knowledge, there are no trials in humans looking at the effects of polysorbates specifically on the gut. Polysorbates are considered safe in low concentrations by the ESFA, but until there is more data on their effects in humans, it may be best to limit these rather than totally avoid.

Verdict: Limit

Monoglycerides and diglycerides of fatty acids

Mono- and diglycerides of fatty acids (E471 and E472) are naturally found in fats from certain plants and animal tissue. They are a commonly used emulsifiers in the UK and often found in bread and other baked goods, ice cream.

Typically, mono- and diglycerides used as food additives are obtained by the hydrogenation of seed oils such as soybean or cotton seed. Hydrogenation is a process which converts liquid fat into a solid fat at room temperature. This is also leads to the production of trans fatty acids or trans fats. Therefore, monoglycerides and diglycerides contain small amounts of trans fats.

Trans fats are linked to an increased risk of cardiovascular disease. A meta-analysis published in the British Medical Journal found a link between higher consumption of these types of emulsifiers with cardiovascular disease, coronary heart disease and cerebrovascular disease (17). It’s unclear whether this is because of the trans fats or the fact that these are one of the more common emulsifiers used in the UK and higher consumption of ultra-processed foods are also high in sugar and saturated fat.

Verdict: Limit

Summary

Ultimately, if you find that you are consuming lots of these emulsifiers every day, then that may suggest you need to reduce your overall intake of ultra-processed foods. If you consume the occasional food that contains an emulsifier, then you probably do not need to worry about it. Regular consumption of any ingredient or food can lead to changes in the gut microbiota. Try to try a follow a diet that is predominantly of whole or minimally processed foods, such as the Mediterranean Diet.