Emulsifiers: We Put Detergent in Toothpaste. Why?

Oil and water don't mix.

Industry fixed that problem with emulsifiers and surfactants—molecules designed to interact with both water and fats. They keep processed foods creamy, cosmetics smooth and toothpaste nicely blended.

Very clever chemistry.

But there's a catch.

Your mouth and gut are not mixing bowls.

They are living biological surfaces protected by cell membranes, mucus, saliva and communities of microorganisms. So perhaps we should be asking a more uncomfortable question:

What happens when we repeatedly expose those surfaces to detergent-like chemicals?

Yes, there's detergent in your toothpaste

One of the most common toothpaste ingredients is sodium lauryl sulfate—SLS.

SLS is a surfactant and detergent. It breaks surface tension, helps ingredients disperse and produces that satisfying mouthful of foam.

And here's the interesting bit:

Your teeth don't need the foam.

We've simply learned to associate bubbles with cleanliness.

SLS can also irritate oral tissues. In susceptible people it has been associated with irritation and recurrent aphthous ulcers, and some evidence suggests that switching to SLS-free toothpaste can reduce ulcer problems.

So we deliberately put a detergent into toothpaste, spread it over one of the body's more permeable surfaces twice a day—and mostly do it because consumers expect toothpaste to foam.

Worth thinking about.

Then things get more interesting

Your intestinal tract is protected by a mucus barrier that helps keep trillions of gut microbes where they belong.

That barrier is not just slime.

It is part of the biological border between you and your microbiome.

And researchers have discovered that certain food emulsifiers can interfere with this relationship.

Two of the best studied are carboxymethylcellulose (CMC) and polysorbate 80 (P80). Experimental studies have reported disruption of the mucus–microbe relationship, changes in gut bacteria and increased inflammatory activity.

Controlled human research with CMC has also shown that an emulsifier can alter the intestinal microbial environment in some people.

That should make us pay attention.

But they're approved, right?

Yes.

And that matters.

But “approved for use” does not mean “biologically inactive.”

Traditional toxicology asks important questions: Does a chemical cause cancer? Damage organs? Affect reproduction? At what dose does obvious toxicity appear?

The microbiome has forced us to ask a much subtler question.

What if a substance doesn't poison us in the conventional sense, but gradually changes the ecosystem living inside us?

We have only recently developed the tools to investigate that properly.

And there is another elephant in the room.

Most safety testing necessarily examines chemicals individually.

We don't consume them individually.

Breakfast cereal, protein bars, sauces, ice cream, toothpaste, cosmetics, medications and supplements can expose us to numerous emulsifiers, surfactants and other additives during an ordinary day.

One might be harmless.

What about five?

Or ten?

Every day?

For fifty years?

Those questions are considerably harder to answer.

Welcome to the experiment

From an evolutionary perspective, this is all extraordinarily new.

For almost the entire human story, our intestinal lining and microbiome encountered foods that were recognizably foods.

Then industrial processing arrived.

Within an evolutionary blink we introduced surfactants, stabilizers, thickeners, gums and chemically modified emulsifiers into everyday life.

Some are probably innocuous. Some are naturally derived. And they certainly shouldn't all be thrown into the same toxicological basket.

But neither should we pretend our biology has nothing to say about them simply because regulators permit their use.

“New to nature” doesn't automatically mean dangerous.

But it does mean our long evolutionary history provides little reassurance about chronic exposure.

My approach?

Don't panic.

Just turn the packet around.

If your toothpaste contains SLS and you don't need it, why not choose one without it?

If two foods are nutritionally similar but one contains six additives required to hold, thicken, stabilize and emulsify it, I know which one I'd choose.

And whenever possible, eat food that doesn't require a chemistry lesson before lunch.

An egg doesn't need polysorbate 80.

An apple doesn't need carboxymethylcellulose.

A piece of fish doesn't require a stabilizer.

The question isn't whether one mouthful of emulsifier is going to make you sick. It almost certainly isn't.

The better question is whether lifelong exposure to mixtures of biologically active additives is something we should accept without asking questions simply because each ingredient has passed a regulatory safety assessment.

We're already conducting that experiment.

The uncomfortable part is that we're the laboratory animals.