CulinarySourced entry

Irish Moss

Chondrus crispus

Sea moss, a red seaweed used as food and medicine, though no medicinal benefit has been proven. It's a source of carrageenan, a food thickener.

What is Irish Moss?

Plant family: Gigartinaceae, a family of red seaweeds
Parts used: The whole seaweed, often made into a gel
Where it grows: Rocky shores of the northern Atlantic Ocean, between the high and low tide lines
Genus: Chondrus
Species: crispus

Sea Moss, Chondrus crispus, Carrageen Moss

Too much iodine from seaweed eaten by breastfeeding mothers has suppressed the thyroid in their babies. Avoid sea moss while breastfeeding unless its iodine and heavy metal levels are shown to be low enough to be safe.[1]

Sea moss can contain toxic heavy metals, such as arsenic, lead, cadmium and mercury, from the water it grew in. It also contains iodine, and the amount can be high.[1]

These are traditional uses, not proven treatments.

Irish moss, also sold as sea moss, is a red seaweed used as food and medicine, though no medicinal benefit has been proven. It contains carrageenan (a gel used as a food thickener), other carbohydrates and many minerals, including iodine.[1]

Lab and animal results show what might be worth studying in people. They don't show that the herb has these effects in humans.

Europe's food safety agency reviewed carrageenan, the gel taken from red seaweeds. It isn't absorbed whole by the body, and animal studies at high doses found no harm, no cancer risk and no damage to genes. Because some data were missing, the agency kept its safe daily limit only as temporary while more research is done.[2]
Technical detail: temporary group acceptable daily intake 75 mg/kg body weight per day for E 407 and E 407a; NOAEL up to 7,500 mg/kg bw per day in chronic rat studies.
In 2013, scientists read Irish moss's full genetic code, finding about 9,600 genes. It's a small seaweed, up to 20 cm long, that grows on rocky North Atlantic shores. The study found the genes it uses to build carrageenan in its cell walls, and an unusually large set of genes for handling halogens, a group of elements in seawater that includes chlorine, bromine and iodine. This is basic biology research and says nothing about health effects.[3]
Technical detail: 105-Mbp genome; ι- and κ-carrageenan in the gametophyte and λ-carrageenan in the sporophyte; galactose-6-sulfurylases and haloperoxidases.

Can contain heavy metals and a lot of iodine. Avoid while breastfeeding unless tested.

This information is educational and traditional in nature, and is not a substitute for professional medical advice.