Published 29th May 2025
Carrageenan (emulsifier): How does it affect health?
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Food additives are a diverse group of compounds with a wide variety of uses. Some add color or flavor, for instance, while others extend shelf life or stop a product from separating.
Some compounds added to foods, like vitamins and minerals, can have an overall positive effect on some people’s health; some additives are likely neutral for health, while others may carry health risks.
Of course, before using an additive, food manufacturers have to show that it’s safe. However, as part of this testing, they don’t investigate its impact on all aspects of health, notably how it might affect levels of inflammation or the gut microbiome.
In this article, we’ll focus on a controversial additive that some scientists are concerned about: carrageenan.
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What is carrageenan?
Carrageenan is an emulsifier, which means it helps prevent compounds from splitting, like oil and water in sauces or spreads. It’s also used as a gelling agent that improves food texture.
Extracted from red seaweed, carrageenan is formed of long chains of sugar molecules attached to sulphate groups (a combination of sulphur and oxygen).
Its long chains allow it to curl into helical structures, producing a gel at room temperature. This property helps manufacturers stabilize and thicken food products.
Mostly farmed in Indonesia and the Philippines, carrageenan is used in a wide range of food items, including many:
desserts
ice cream and cream
milkshakes
yogurts
salad dressings and sauces
beer
pâtés and processed meats
plant milks and infant formula
diet sodas
Carrageenan is often added to vegetarian and vegan alternatives because it’s a good replacement for gelatin made from animal tissues. It also regularly appears in low-calorie foods because it’s a good substitute for fat.
Manufacturers also use it in a variety of non-food items, like shoe polish, fire-fighting foam, and shampoo.
Over recent decades, our consumption of carrageenan has increased hugely. In the 1980s, the average adult in the U.S. consumed up to 0.1 grams per day. Today, people consume around 2.5 grams per day — that’s 25 times more.
Although the United States Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA) consider it safe, some scientists are less sure.
Carrageenan and health
Carrageenan is generally considered to be safe because our digestive enzymes can’t break it down, meaning that the majority of it exits our body. However, this isn’t the whole story.
While your digestive enzymes can’t break down carrageenan, there’s evidence that certain gut microbes produce enzymes that can. Stomach acid, especially if combined with acidic foods, may also break it down.
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This matters because when carrageenan is broken down into smaller chains of sugars, it is no longer considered safe. The resulting shorter chains of sugars are called degraded carrageenan or poligeenan.
The International Agency for Research on Cancer considers poligeenan a possible human carcinogen, and researchers use poligeenan to cause ulcers and colon cancer in animal studies.
Importantly, there is an ongoing debate about how much carrageenan gets broken down to form poligeenan in humans.
Next, let’s look at some research.
In cells and animals
Much of the research to date has focused on laboratory-based studies and animals. We need to be careful when interpreting these, and we can’t always extrapolate the findings to humans.
With that said, we'll briefly cover some to give you the gist:
Using a lab-based model of the human gut microbiome, scientists found that carrageenan altered the microbiome's composition and increased levels of inflammatory markers.
A study involving a lab model of the digestive system and cell cultures concluded that carrageenan interfered with protein digestion and disturbed the gut wall, making it more “leaky.”
Research using healthy human intestinal cells found that carrageenan increased markers of inflammation.
A mouse study found that carrageenan worsens inflammation in animals that already have gut inflammation.
While lab and animal studies are a vital part of the scientific process, again, we need to interpret the results cautiously. You are not a single cell or a mouse, after all.
Some studies have recruited humans, though, particularly people with inflammatory bowel disease (IBD), so we’ll look at those next.
Carrageenan and IBD
IBD is a group of chronic autoimmune conditions characterized by intestinal inflammation. The two most common forms are Crohn's disease and ulcerative colitis.
The precise causes of IBD are still not known, but diet certainly plays a part — the Western diet, in particular.
Conversely, following a plant-based diet, like a Mediterranean-style diet, is associated with improved symptoms and reduced risk.
Interestingly, plant-based diets linked to reduced IBD symptoms are also naturally low in carrageenan. However, that’s just a correlation, so we mustn’t read too much into it.
Still, some scientists believe that carrageenan may either play a part in causing IBD or at least make symptoms worse. And there is some evidence from human studies.
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Ulcerative colitis study
A small study published in 2017 recruited 12 people with ulcerative colitis. This condition is marked by periods with relatively minor symptoms followed by flare-ups and relapses, where symptoms become worse.
The scientists wanted to understand whether avoiding carrageenan would increase the length of time between relapses. In other words, keep them symptom-free for longer.
All participants followed a no-carrageenan diet. Some took placebo capsules each day, while the rest took carrageenan capsules. Importantly, the carrageenan capsules contained less of the compound than is consumed in an average diet.
The scientists followed the participants for a maximum of 1 year, with regular phone check-ins. In their paper, they write:
“Three patients who received carrageenan-containing capsules relapsed, and none of the patients who received placebo-containing capsules relapsed.”
Also, the researchers found that markers of inflammation increased in those taking carrageenan, but not in those taking a placebo.
We know that carrageenan reliably sparks gut inflammation in animals and human intestinal cells, but we need more research in healthy humans.
It’s worth noting that research into other types of emulsifiers has found “a positive correlation between inflammatory bowel disease and emulsifier consumption,” so the evidence against emulsifiers in general is mounting.
Other health conditions
Most research into carrageenan has focused on IBD or gut health more generally, but some scientists have looked at links to other conditions.
One study found a correlation between increased intakes of carrageenan over time and an increased incidence of breast cancer.
Because this is just a correlation, the quality of evidence is quite low, but the authors believe further research is justified.
Another group of scientists looked for an association between carrageenan intake and type 2 diabetes in more than 100,000 participants. They found that higher intakes of carrageenan were associated with an increased risk of type 2 diabetes.
Published in 2024, this was the first study looking at the relationship between emulsifiers like carrageenan and diabetes risk. Again, the scientists call for more investigations.
What should you do?
As we’ve seen, there is a solid amount of evidence from animal and lab studies that carrageenan might damage health. Studies in humans, however, are few and far between, so the evidence base isn’t as compelling.
While scientists continue to investigate, your best bet is to focus on foods we know are healthy.
By following a diet that focuses on eating a diverse range of plants, including nuts, seeds, herbs, beans, and spices, you will support your health and naturally avoid emulsifiers like carrageenan.
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