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If you have a weak stomach, I don’t recommend watching one of the many videos on social media of influencers dipping their spoons into a jar of sea moss and putting mounds of the congealed substance – with a texture resembling congealed oil or snot – straight into their mouths.
“People have this assumption that it’s disgusting,” one influencer says, holding a spoonful in her mouth and, while seemingly trying not to swallow, insisting: “It’s really not.” Another dry-retches as soon as it passes her lips.
Sea moss, which is closely related to Irish moss, usually comes in a jar, costs upwards of $35, and, depending on added ingredients, can be bubblegum pink or aquamarine. Many labels describe the “natural” product as containing added chlorella.
What is sea moss and why is it on TikTok?
“It cleared up all my acne” and “it resolved my gut issues” are common claims, used about the potential health benefits of sea moss. “It contains over 92 essential nutrients your body needs,” another influencer claims, recommending two tablespoons on an empty stomach, though the video never shows her actually swallowing it even though she repeatedly lifts a heaped spoon towards her mouth.
Dr Margaret Murray, the course director for Swinburne University’s bachelor of nutrition, says both chlorella and sea moss are types of algae, and a lot of research has been done on algae and algal products to investigate potential human health benefits. Its growing use in wellness products is part of the reason the “algae products market” is expected to reach A$5.2bn (US$3.7bn) by 2034.
“A lot of this research has been conducted using cell or animal models with fewer studies using human participants,” Murray says, with some of this early stage research suggesting algae may help to manage blood sugar levels or support healthy cholesterol. However, there are many reasons why animal or cell studies are poor predictors of impacts in humans.
“It is also unlikely that an average healthy person is going to notice significant benefit in these areas,” Murray says. So while those who have elevated blood sugar levels or cholesterol levels may be most likely to see an effect, “we don’t know enough yet to provide evidence-based guidance on doses or frequency of intake,” she says, with further, stronger studies needed. “Using these products as complementary therapies should be carefully managed with the support of an accredited practising dietitian and medical professional.”
Yes, algae is nutrient-dense. No, you don’t need supplements
Murray says it is true that algae are very nutrient-dense, containing vitamins, minerals, amino acids and fibre. “The exact nutrient composition will differ between different species and products,” she says. “Products like sea moss and chlorella can contribute to overall nutrient intake. But there is no additional benefit from getting nutrients from these products compared with whole foods. I always advise to get nutrients from food first, and supplements as a backup plan.”
Associate Prof Evangeline Mantzioris, an accredited practising dietitian and sports dietitian, says sea moss also contains iodine, which can be problematic for people with thyroid-related health issues. It can also contain heavy metals. “Like other minerals, sea moss will accumulate heavy metals if they are present in the seawater they were harvested from,” she says.
‘Natural’ doesn’t mean ‘safe’ or ‘beneficial’
There is very limited evidence from one human study that chlorella may reduce mercury levels in humans, she says, but the sample size was small. Both Mantzioris and Murray say claims that the products are “natural” do not mean much. “Just because something is natural, or found in nature, doesn’t mean it is safe or beneficial to humans,” Murray says. “There are plenty of dangerous substances that are also natural, for example death cap mushrooms.”
Overall, Mantzioris says: “If consumed in normal amounts as part of healthy balanced diet they (moss and chlorella) should be fine, especially for communities that have been consuming them as part of their cultural diet.”
But Murray says: “Adding chlorella or sea moss to an otherwise suboptimal dietary pattern is not going to completely counteract poor dietary habits.”
Melissa Davey is Guardian Australia’s medical editor
Antiviral is a fortnightly column that interrogates the evidence behind the health headlines and factchecks popular wellness claims
