Emulsifiers in Processed Foods: Your genes and your microbiome

Our genes and our environment both contribute to our gut microbiome, allowing some species to flourish and keeping others away. How does this all come together to cause the diseases that plague our modern society?

Emulsifiers, Packaged Foods, Inflammation

Research over the past decade shows that emulsifiers in common food products can lead to low-grade inflammation in the gut, especially with certain genetic variations.[ref][ref]

Let’s dive into what these food additives do in the gut and how the alterations caused by gums and emulsifiers increase intestinal inflammation.

What are emulsifiers?

Emulsifiers help solve the age-old problem of getting water and oil to mix. Consisting of a water-loving and oil-loving end, emulsifiers are molecules that are attracted to both oil and water.

Egg yolks are an example of a natural emulsifier.

Some of the first emulsifiers patented for use in foods were a derivative of fatty acids called mono- and diglycerides. Several patents from the 1930’s show mono- and diglycerides being used for shortening – you know, like the Crisco your mom used to use in cookies. Cottonseed oil was cheap and abundant and became the oil of choice in shortening, used instead of lard in baking bread, cakes, and cookies.

These days emulsifiers are used to make food shelf-stable with a good texture. You’ll find emulsifiers on the ingredients labels for:

  • most baked goods
  • ice cream
  • some deli meats
  • pickled products
  • salad dressings
  • sauces
  • coffee creamer
  • and more!

Emulsifiers can also act as surfactants, which reduce surface tension. Surfactants are commonly found in detergents – think about a drop of dish detergent breaking up the grease in a pan.

Commonly used emulsifiers:


  • also known as CMC or cellulose gum,
  • GRAS (generally regarded as safe) by the FDA
  • allowed to be included at up to 2% in various foods

“CMC is used in food under the E number E466 as a viscosity modifier or thickener, and to stabilize emulsions in various products including ice cream. It is also a constituent of many non-food products, such as toothpaste, laxatives, diet pills, water-based paints, detergents, textile sizing, and various paper products. It is used primarily because it has a high viscosity, is nontoxic, and is generally considered to be hypoallergenic as the major source fiber is either softwood pulp or cotton linter.[2][3] CMC is used extensively in gluten-free [4] and reduced-fat food products.”[ref]


  • also known as P80 or Tween 80
  • allowed at levels up to 1% in certain foods

Polysorbate 80 is a surfactant and emulsifier used in foods and cosmetics. Ice cream often includes polysorbate 80 (up to 0.5%) to help it stay smooth. It is also found in a lot of pickles and pickled products.

The acceptable daily intake (World Health Organization) is 25 mg/kg body weight/day, acute toxicity is low, and it is not considered cancer-causing.[ref]

Other emulsifiers including lecithin:

A 2021 study investigated 20 more emulsifiers to see the impact on the gut microbiome. The results showed a couple of important results:[ref]

  • Lecithin and mono- and diglycerides have little to no impact on the gut microbiome.
  • The impact on the gut microbiome from gum arabic, iota carrageenan, locust bean gum, guar gum, and agar-agar is reversible.
  • CMC’s impact on the composition of the gut microbiome may be non-reversible. Additionally “xantham gum, sorbitan monostearate, glyceryl stearate, maltodextrin, and P80 impacted various microbiota parameters, both compositionally and/or functionally, in a non-reversible manner”.

How do you keep intestinal bacteria in the right place?

The intestinal wall is lined with epithelial cells along with a mucosal barrier to keep out microbes and to protect against digestive enzymes.

This mucosal barrier keeps microbes away from the epithelial cells and thus out of the body’s circulation. The microbes in our guts are important and perform a variety of functions for us, including making some vitamins and short-chain fatty acids. But they have to stay in the right spot in the gut…

When the intestinal mucosal barrier is disrupted, your immune system gets activated by microbes in the gut, causing an inflammatory response.

This can lead to autoimmune and inflammatory conditions such as food intolerances, IBD, and diabetes.

So, if a dysfunctional mucosal barrier can cause intestinal and autoimmune disorders, what does a thinner than normal barrier do? According to a scientist at Georgia State University, it causes low-level inflammation, which could be driving weight gain and metabolic syndrome.

Studies of Emulsifiers and the Gut Microbiome:

Decades ago, researchers investigated the toxicity and cancer-causing properties of carboxymethyl cellulose, hydroxypropyl methylcellulose, and polysorbate 80.[ref][ref][ref] These emulsifiers were found to be acceptable for use as food additives.[ref][ref][ref] They have been identified as safe for human consumption by the FDA.

But several new studies within the last couple of years have been looking at the chronic, low dose effect of emulsifiers on the intestinal mucosal barrier. These studies paint a new picture of the health effects of emulsifiers.

Studies on chronic effects of emulsifiers/surfactants:

1. Researchers looked at whether emulsifiers (specifically Carboxymethylcellulose and Polysorbate 80) increased low-grade inflammation, resulting in metabolic syndrome. The results showed:[ref]

  • Carboxymethylcellulose in low levels (0.1 – 0.5% of their food) increased body weight and caused low-grade inflammation.
  • Polysorbate 80 in low levels (0.1 – 0.5% of their food) also increased body weight and caused low-grade inflammation. At the 0.5% level, polysorbate 80 caused dysglycemia.
  • Most importantly, the “Emulsifier-induced metabolic syndrome was also observed in older mice…and persisted for at least 6 weeks after stopping emulsifier consumption”.
  • To sum up, the emulsifiers used in this study caused bacteria to be located closer to the epithelial cells of the intestine. For mice that were genetically susceptible to colitis, this caused colitis.  For normal mice, this caused low-grade inflammation, fat gain, and mild blood sugar level issues.

2. Researchers found emulsifiers caused impaired glycemic tolerance, increased gall bladder size, and reduced intestinal mucosa thickness. The reduced mucosal thickness causes intestinal bacteria to be closer to the epithelial cells and increased inflammation.[ref]

3. Food additives such as emulsifiers, organic solvents, gluten, and nanoparticles used in processed food increase intestinal permeability. Essentially – they caused leaky gut, which may explain the rise in autoimmune diseases.[ref]

4. One study looked at the effect of non-starch polysaccharides vs. food emulsifiers on the ability of E. coli to the mucosa in the intestinal tract. They showed:[ref]

  • plant fibers, such as broccoli and plantain, reduced E. coli moving into the intestinal cells
  • the addition of polysorbate 80 at 0.01% increased E. coli translocation by 59-fold

5. Research (in mice) demonstrates that “regular consumption of dietary emulsifiers, carboxymethylcellulose or polysorbate-80, exacerbated tumor development…. We found that emulsifier-induced alterations in the microbiome were necessary and sufficient to drive alterations in major proliferation and apoptosis signaling pathways thought to govern tumor development.”[ref]


The key as to whether emulsifiers cause intestinal barrier leakiness in people may on genetics. Some (perhaps most) people can eat foods containing emulsifiers without any issues.

Genetic variants impacted by emulsifiers:

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About the Author:
Debbie Moon is the founder of Genetic Lifehacks. Fascinated by the connections between genes, diet, and health, her goal is to help you understand how to apply genetics to your diet and lifestyle decisions. Debbie has a BS in engineering and an MSc in biological sciences from Clemson University. Debbie combines an engineering mindset with a biological systems approach to help you understand how genetic differences impact your optimal health.