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Leaky Gut Genes: Emulsifiers in Processed Foods

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 when combined 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 1930s 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. A good example is how a drop of dish detergent breaks up the grease in a pan.

Commonly used added emulsifiers:

The following emulsifiers/surfactants are common ingredients in processed foods.


Carboxymethylcellulose is a very common ingredient in foods, especially reduced-fat and gluten-free foods. It is also commonly found in ice cream as a stabilizer.[ref]

  • 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
  • made from wood pulp or cotton processing


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 most pickles and pickled products.

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

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:

A 2021 study investigated 20 more emulsifiers to see their 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”.

Leaky Gut and the Intestinal Barrier

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…

The mucosal barrier is really two layers – an inner layer that is firmly attached and an outer layer that is thicker and looser. The inner layer has few bacteria in it and contains secreted peptides that are antibacterial. The outer mucosal layer contains many different types of gut bacteria.[ref]

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 drive 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.

7 Studies on chronic effects of emulsifiers/surfactants:

1. Researchers examined 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.

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

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:

  • 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]

6. In a recent animal study, both carboxylmethylcellulose and polysorbate 80 altered the intestinal mucosa, impacting barrier and structural properties. This changed the way that bacteria, such as E. coli, interacted with intestinal tissue.[ref]

7. Another recent study showed CMC, polysorbate 80, and soy lecithin shifted the gut microbiome away from the ‘good’ bacteria that produce short chain fatty acids. [ref]


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

Leaky Gut Genotype Report:

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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 from Colorado School of Mines 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.