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The Guardian - UK
The Guardian - UK
Clare Finney

TikTokers reckon sea moss can help you lose weight and have better sex. What does the science say?

Chondrus crispus, traditionally used in food manufacturing for gelling, thickening and stabilising, is now being touted for its health properties.
Chondrus crispus, traditionally used in food manufacturing for gelling, thickening and stabilising, is now being touted for its health properties. Photograph: Richard Wayman/Alamy

It is 8am on a Tuesday and I’m stirring jellified sea moss into my morning brew. Or at least, I’m trying to – little lumps of the stuff keep bobbing up and eyeballing me from the milky surface. Clearly, a plant that grows on rocks by the Atlantic coast doesn’t dissolve. Still, I drink up, on the advice not only of the woman I bought it from, at a south London farmers’ market, but Kim Kardashian, Cardi B and a host of TikTokers who have been adding it to their tea, smoothies, yoghurts, juices – even eating it straight from the jar – in pursuit of its alleged health benefits.

The texture is as I expected – slimy, like a juiced oyster – but the flavour eludes me. There is a back note of muddy seawater, but otherwise it tastes of very little. Like seaweed, sea moss is a generic term that covers various species of algae growing in coastal waters. The most famous of these is Irish moss, formally known as Chondrus crispus, which can be found in rocky regions around the Irish coast, as well as on the Atlantic coasts of Britain, mainland Europe and North America. Historically, this moss was harvested for carrageenan, which is extracted to be use in food manufacturing for its gelling, thickening and stabilising properties. Since being branded a superfood, however, it has become more widely available raw and in supplement form: in pills, powders, gummies and the gel that is still bobbing around in my cuppa.

Sea moss’s supposed health benefits prove as elusive as its flavour. Promises on TikTok videos, wellness blogs and moss products themselves range from weight loss to clearer skin, increased libido and improved fertility – yet few of these claims have been subject to the kind of research that is required for its health benefits to be registered by the European Food Safety Agency.

“Since there hasn’t been much research on sea moss, it is hard to say whether it is safe for everyone,” says Beth Czerwony, a registered dietitian with Cleveland Clinic’s Center for Human Nutrition. Chondrus crispus is rich in iodine, and like all sea vegetables, it is a good source of fibre. One study found that supplemental sea moss improved the functioning of the immune system in salmon – one of the reasons the trend blossomed during Covid – but there has been no further research to show if that is true for humans.

Caherush on the Atlantic coast in Ireland is one of the places where red moss can be found.
Caherush on the Atlantic coast in Ireland is one of the places where red moss can be found. Photograph: Tatiana Shkondina

Czerwony views sea moss’s other benefits with similar caution: it “may” be good for the gut, and it “may” help with weight loss and improve heart health, thanks to the fibre. Iodine is useful in supporting thyroid function, but most people get enough of it from their regular diet and “because there is inconsistency in the amount of iodine in sea moss, you may end up consuming too much, which can lead to hypothyroidism or underactive thyroid,” she warns. What is more, she says: “Some sea vegetables, depending on location, may contain heavy metal.”

It seems, then, that knowing the origin and cultivation of your sea moss is vital, and you are better off opting for Chondrus crispus from producers such as the Sea Moss Boss and the Moss Way, which can name their harvesters and have tested their moss for heavy metals.

Research has been largely concentrated on Chondrus crispus, but many of those jumping on the wellness wagon are making the same claims for other species of red algae, such as gracilaria, which grows in warmer waters. More confusingly still, because thousands of indentured Irish labourers who were transported to the Caribbean during the 18th century continued their practice of drinking the local sea moss, gracilaria became known colloquially as “Irish moss”. Even today, Jamaicans make a drink they call Irish moss, inspired by the recipe these early immigrants brought over.

The food writer Melissa Thompson, author of Motherland: A Jamaican Cookbook, says: “Irish sea moss [which is in fact gracilaria] is cooked up with condensed milk, cinnamon and sugar. It’s also served with fruit juice – the moss is boiled up and strained and mixed with juice. The carrageenan gives it a real thickness. “It’s one of the foods said to put ‘lead in the pencil’ and help virility.”

In short, sea moss is the latest in a long line of medicinal plants that have been consumed in some communities for centuries, but which have not been subject to statutory regulation or large-scale randomised control testing before being seized on by the wellness scene.

Tee McKen, co-owner of the Sea Moss Boss, which sells Chondrus crispus sourced from County Donegal, has mixed views on sea moss’s rise in popularity: “It’s made more people aware of the benefits, but the claims are often exaggerated, which gives it a negative spin.” She attributes the trend to Alfredo Bowman, a self-proclaimed healer known as Dr Sebi. “He didn’t have any credentials, but he claimed to heal people from certain ailments, and he mentioned Chondrus crispus.” Bowman died in 2016, but TikTokers still talk about him in reference to sea moss. “They will say: ‘This moss is Dr Sebi approved.’”

For McKen, the proof is in the practice. Her family is Jamaican and her husband is Irish, so they are well placed to talk about sea moss’s value to those communities. “It’s a staple in Jamaica,” she says. “They live long and they say it’s down to taking [gracilaria] sea moss.”

In Scotland, where Chondrus crispus grows in abundance, it has been primarily used to set puddings. “Florence Marian McNeill has a recipe for sea moss jelly in her book The Scots Kitchen from 1929,” says the Scottish food writer Robbie Armstrong, who also notes that oral records and recipes suggest Highlanders and islanders have long regarded it as an aid for “indigestion, bronchitis and relining the stomach after a heavy drinking session”.

In short, consuming well-sourced sea moss in moderation is unlikely to be bad for you – it may even be good. Personally, though, I would rather try a carrageen moss pudding or a Jamaican Irish moss drink, perhaps with a tot of rum mixed in – something that treats sea moss as it has been used historically: as an ingredient, rather than a superfood.

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