Dec. 6, 2021 — A type of marine algae known as ulva, or “sea lettuce,” that’s a diet staple in places like Japan, New Zealand, and Hawaii may have another benefit for people. Lab experiments suggest that ulvan, an extract from this type of algae, may help fight COVID-19.

Other forms of edible seaweed have also shown promise as antivirals against COVID — at least in very early studies done in test tubes and animals. But ulvan has been tested as an antiviral treatment against certain agricultural and human viruses, too. This caused researchers to wonder whether ulvan might help prevent COVID infections.

To find out, scientists grew ulva algae in a lab, extracted ulvan, and then exposed cells in test tubes to both the coronavirus and to ulvan. When cells were exposed to ulvan, they didn’t get infected with the coronavirus, according to experiment results reported inPeerJ.

In Test Tubes

That said, it’s possible that the process used to extract ulvan from seaweed may impact its antiviral properties. Investigators compared two extraction methods and found one of them resulted in ulvan with more than 10 times the virus-fighting power. This suggests that more research is needed to refine the best method to develop ulvan with the best antiviral properties, the researchers point out.

One limit of the experiment is that differences in the chemical makeup of the two extracts might have influenced the outcome, making it hard to know for sure how much of the antiviral activity might come directly from ulvan as opposed to these chemicals.

And even if the seaweed extract proves effective in more lab tests, it would still need to be tested in animals and humans. But should it prove effective in human trials, seaweed extract has the potential to help prevent COVID infection in people who can’t easily afford or access vaccines, particularly in low-income countries, the study authors conclude.