What are emulsifiers? Emulsifiers are food additives used to stabilize and blend ingredients that would naturally separate, such as oil and water. When ingredients like these are mixed together they are called an emulsion. Forming and maintaining emulsions contributes to extending the shelf life of a product.
Emulsifiers are widely used in processed foods like baked goods, ice cream, and dressings. But they are also added to supplements and medications like pain relievers and colic and gas drops for babies [1].
The FDA has granted food emulsifiers the status of generally recognized as safe (GRAS). This means that through laboratory and animal experiments, these additives have been found to be nontoxic, nonirritant, and noncarcinogenic.
However, this evaluation doesn’t consider things such as effects on the gut microbiome.
As it turns out, while the human digestive system can’t break down emulsifiers, gut bacteria can. Because of this, emulsifiers have the potential to change the gut microbiome composition.
Is it a good change or a bad change? Let’s look at the effects of some of the most used emulsifiers.
TLDR? Scroll to the summary table at the end.
Sodium carboxymethyl cellulose (CMC)
CMC (aka E466) is obtained from treating wood pulp with strong chemicals. It can be found in foods like milk, ice cream, and some baked goods; but also in pharmaceutical products like gas relief drops and acetaminophen or ibuprofen liquid medicine for babies.
CMC has been widely tested in laboratory and animal studies, which have revealed its harmful effects on the gut environment. Besides, a human study further corroborated these findings by confirming similar effects on the gut microbiome.
Some of the reported effects in animal and human studies include:
- Gut inflammation [2]–[6].
- Increased levels of unfriendly Enterobacteriaceae and decreased levels of beneficial Faecalibacterium prausnitzii and Akkermansia muciniphila [4], [6]–[8].
- Reduced gut microbiome potential to produce short-chain fatty acids and essential amino acids [7], [9].
- Lower thickness of the mucus gut barrier [6], [7].
- May contribute to obesity/metabolic syndrome [3].
- May exacerbate food allergy symptoms [10].
Is it safe to eat? Not so much for your microbes.
Polysorbate-80
Polysorbate-80 (aka P80, Tween 80, E433) is a detergent used in food, cosmetics, and pharmaceuticals.
It is also used in some colic drops and ibuprofen liquid medicine for babies.
The reported effects of prolonged consumption of P80 are similar to those of CMC according to laboratory and animal studies:
- Gut inflammation [3], [4], [6].
- Increased levels of unfriendly Enterobacteriaceae and decreased levels of beneficial Bacteroidaceae, Faecalibacterium prausnitzii, and Akkermansia muciniphila [4], [6], [8].
- Lower thickness of the mucus gut barrier [6].
- Obesity/metabolic syndrome [3].
While there are no human studies for P80, it’s highly possible that, similar to other emulsifiers, it may have similar harmful effects on the gut.
Is it safe for the microbiome? Avoid this one if you can.
Xanthan gum
Xanthan gum (aka E415) is produced by the bacterium Xanthomonas campestris, which lives in plants. It is widely used as a stabilizer and thickening agent in food and medications like gas relief drops and acetaminophen or ibuprofen liquid medicine for babies.
It’s also sometimes added as a thickener to formula used for babies with swallowing difficulties or regurgitation [11].
But in 2011-2012, a thickener made of xanthan gum was linked to some cases of necrotizing enterocolitis (NEC) when used in premature babies [12], [13].
The FDA thus warned against the use of xanthan gum in premature babies. However, in 2017 a report from the Panel on Food Additives and Nutrient Sources added to Food reevaluated its safety and concluded that the NEC cases were unlikely to be related to this thickener [14].
The effects of xanthan gum on the gut microbiome are not clear. Animal studies have shown that it protects against Clostridioides difficile during antibiotic treatment [15], but laboratory studies using human gut microbiota reported that xanthan gum altered bacterial composition and stimulated inflammation [16].
Is it safe to eat? It depends.
Gum arabic
Also known as Acacia gum or E414, gum arabic is a gummy secretion from the Acacia senegal tree. It is considered a prebiotic because gut bacteria digest it to produce butyrate. It’s usually added to desserts, candies, and carbonated drinks.
Gum arabic has been traditionally used in African-Middle Eastern countries as a medicine for stomach disease. Laboratory experiments and clinical trials in adults have shown that this food emulsifier actually has beneficial effects on the gut microbiome. For example:
- It promotes the growth of beneficial Bifidobacterium and Lactobacillus, and it inhibits the growth of the pathogen Clostridium histolyticum [17], [18].
- It has an antibacterial effect against pathogenic Staphylococcus aureus and Escherichia coli [19].
- Consumption of gum arabic reduces blood pressure and body mass index in adults, among other benefits [20]–[22].
- It has been used as a supplement for malnourished children aged 6-59 months, with positive effects [23].
Is it safe for your microbes? Yes.
Carrageenan
Carrageenan (aka E407) is obtained from red algae and it is used as an emulsifier in some brands of chocolate milk and in liquid baby formula. It can be digested by gut bacteria.
Animal and laboratory studies report that the effects of carrageenan consumption are:
- Gut inflammation [24].
- Decreased numbers of beneficial Akkermansia muciniphila and Bifidobacterium, and increased numbers of unfriendly Escherichia [24], [25].
- Increased production of proinflammatory molecules [16].
- Disruption of the gut barrier and reduced production of short-chain fatty acids [26].
The effects of carrageenan have also been evaluated in humans. A carrageenan-free diet appeared to be beneficial for pre-diabetic patients [27], whereas carrageenan consumption promoted inflammation and relapse in patients with ulcerative colitis in remission [28].
Is it safe for the microbiome? Avoid it if you can.
Arabinogalactan
Arabinogalactan (aka E409) is obtained from plants. It is actually a component of gum arabic. It’s added to some essential oils, non-nutritive sweeteners, and dressings.
Similar to gum arabic, it appears to provide benefits for the gut microbiome:
- Clinical trials in adults have shown arabinogalactan boosts the immune response [29]–[31].
- Its consumption leads to significant increase of Bacteroidetes and decrease of Firmicutes [32]. Firmicutes are generally more abundant in individuals with obesity, and some studies have suggested a potential link between a higher Firmicutes-to-Bacteroidetes ratio and weight gain [33].
- A clinical trial with children from 3 to 36 months of age with acute diarrhea reported that a preparation of Lactobacillus paracasei B21060 plus arabinogalactan and sugars significantly reduced the duration of diarrhea [34].
Is it safe to eat? Yes, and microbes love it.
Soy lecithin
Soy lecithin (aka E322) is obtained from soybeans. It is more widely used than CMC and P80, mostly in baked goods, ice creams, and chocolate. It is also used as an emulsifier in infant formula.
Animal and laboratory experiments suggest it could be disruptive for our gut microbiome.
This is because it increases the amount of unfriendly gut bacteria, decreases anti-inflammatory butyrate production, and increases propionate production [35], [36]. However, it’s worth noting that in another study, soy lecithin did not have an important impact on the gut microbiome [16].
Is it safe for your microbes? The jury is still out on this one.
Glycerin
Also known as glycerol and E640, glycerin is used as a sweetener, emulsifier, and moisturizing or thickening agent. Liquid acetaminophen and ibuprofen medications for babies usually contain glycerin.
Glycerin can be digested by some gut bacteria. This leads to the production of acrolein, a molecule that acts as a double-edged sword. It can be beneficial because it reacts with dietary carcinogenic compounds, reducing their toxicity. But on the other hand, it is itself a toxic and carcinogenic antimicrobial agent [37], [38].
Is it safe for the microbiome? Hard to say.
Our recommendation on food emulsifiers
If possible, always check for emulsifiers in the list of ingredients when choosing a product. While most evidence concerning the harmful effects of emulsifiers comes from animal and laboratory studies, a human clinical trial has shed light on CMC, confirming its negative influence on the gut microbiome.
Realistically, completely avoiding harmful emulsifiers is a daunting task unless you exclusively consume non-processed foods. However, we firmly believe that minimizing exposure to these food additives whenever possible is a wise approach. This is especially important for infants, whose developing gut microbiome requires special attention.
When possible, prefer products that don’t contain CMC, P80, or carrageenan. These emulsifiers are often listed as “other ingredients”, “inactive ingredients”, or “non-medicinal ingredients.”
Here are some examples:
Summary table for commonly used food emulsifiers
