Irish Moss: Health Benefits, Nutrition, and Uses

Despite its name, Irish moss (Chondrus crispus) isn’t really a moss: It’s a type of algae, or seaweed. This red, branching seaweed is found on the coast of the Atlantic Ocean in Britain, Europe, and North America. Irish moss plays an important role in a number of industries, but one of its most common uses is in food. 

Irish moss is largely made of a jelly-like substance known as carrageenan, which makes Irish moss so broadly useful. Carrageenan can be used as a vegan substitute for gelatin, as well as a general emulsifier, so it can be found in everything from ice cream to infant formula. There is some significant controversy surrounding carrageenan and Irish moss, with studies on both sides showing that carrageenan may have both positive and negative health effects.

Here’s what you need to know about Irish moss’s effect on your health:

Health Benefits

Irish moss and other seaweeds can provide important health benefits. For example, seaweed is rich in iodine, which is an important nutrient for your thyroid. Iodine helps your thyroid produce hormones that control your metabolism, nerves, and bone growth.

In addition, Irish moss and seaweed may provide health benefits like:

Better Hea rt Health

Seaweed, including Irish moss specifically, is one of the best plant sources of omega-3 fatty acids. These fats are critical for a healthy heart. In fact, getting enough omega-3 fatty acids is connected to a lower risk of heart disease, blood clots, high cholesterol, and high blood pressure. Eating seaweed and Irish moss can help you improve your heart health even if you’re not a fan of fish. 

May Help Control Blood Sugar

One substance found in Irish moss that may be helpful is fucoxanthin. This is a carotenoid that gives Irish moss its rich red-brown color.

Studies have shown that fucoxanthin may have significant benefits for regulating blood sugar levels. It appears to help the body respond to insulin more effectively, meaning that your body can control its own blood sugar with less work. For people with diabetes, eating Irish moss may help prevent blood sugar spikes or crashes.

Reduced Risk of Cancer

Fucoxanthin and other carotenoids found in Irish moss act as antioxidants, which are known to help fight free radicals. Uncontrolled free radicals can damage cells, causing them to grow in dangerous ways — damaged cells can become cancerous. By eating seaweed like Irish moss, you may be able to reduce your risk of developing certain cancers. 


Health Risks

Although Irish moss offers many health benefits and can improve your body’s overall function, some studies have shown that carrageenan may have negative effects.

Under certain circumstances, carrageenan can be converted into “degraded carrageenan,” or poligeenan — which is known to be toxic and may cause several health problems. There is currently no scientific evidence to show that your body can convert carrageenan to poligeenan. However, some seaweed can contain poligeenan naturally.

May Cause Intestinal Inflammation

Poligeenan can lead to inflammation of the intestines, causing problems with nutrition absorption. This can also lead to discomfort and bloating over time. It may also be linked with colitis and symptoms of Crohn’s disease.

May Cause Stomach Ulcers

In large amounts, poligeenan has also been shown to cause stomach lesions and ulcers in animal studies. More poligeenan is generally connected to larger ulcers. 

May Lead to Stomach and Bowel Cancer

Finally, poligeenan has also been linked to polyps that may become cancerous. Poligeenan appears to cause problems in the digestive tract that lead to cell mutations commonly found in cancers, particularly in cases where ulcers are found. 

It’s important to note that carrageenan has none of these effects. The U.S. Food and Drug Administration (FDA) has determined that carrageenan is safe to use as a food additive, and the human body cannot produce conditions to convert carrageenan to poligeenan.

Amounts and Dosage

The FDA recommends that people consume no more than 225 micrograms of iodine daily. Since Irish moss is rich in iodine, you may want to be cautious when it comes to overeating it. In general, eating one to two servings, or 2 to 4 tablespoons, is considered safe and healthy. 

WebMD Medical Reference Reviewed by Dan Brennan, MD on November 08, 2020



Britannica: “Irish Moss.”

Cleveland Clinic: “Omega-3 Fatty Acids.”

Critical Reviews in Food Science and Nutrition: “Clarifying the confusion between poligeenan, degraded carrageenan, and carrageenan: A review of the chemistry, nomenclature, and in vivo toxicology by the oral route.”

Critical Reviews in Toxicology: “A critical review of the toxicological effects of carrageenan and processed eucheuma seaweed on the gastrointestinal tract.”

ESHA Research, Inc., Salem, Oregon.

Journal of Applied Phycology: “Melanoma and brown seaweed: an integrative hypothesis.”

Lipid Technology: “The carotenoid fucoxanthin from brown seaweed affects obesity.”

Lipids in Health and Disease: “Polyunsaturated fatty acids in various macroalgal species from north Atlantic and tropical seas.”

National Institutes of Health: “Iodine.”

Scientific American: “The Carrageenan Controversy.”

U.S. Department of Agriculture: “Seaweed, irishmoss, raw.”

U.S. Food and Drug Administration: Code of Federal Regulations Title 21.

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