Rooibos tea is a uniquely South African product. The plant, Aspalathus linearis, grows mainly in the Cederberg area of the country’s Western Cape province. And it’s not just a tasty beverage. It is caffeine-free; research has proved that it has anti-inflammatory properties. It’s also been found to ease pain and reduce allergies. Rooibos is also good for heart health.

As our new study shows, rooibos tea—specifically unfermented or green rooibos—may also help to reduce anxiety. Our research found that this extract of the tea, prepared using ethanol rather than water, has anxiolytic properties. This means it prevents or lessens the degree of anxiety a person experiences.

We didn’t reach this conclusion by testing the tea on human subjects, though. There’s a huge variation in anxiety severity, so a study in humans would require too many participants to give us sufficient statistical power, and thus be too expensive.

Instead, we used zebrafish. The small, striped tropical fish may seem like an odd choice until you realize that they are genetically quite similar to humans. For more than 80% of the genes known to cause disease in humans, similar genes are represented in zebrafish.

This fact prompted Stellenbosch University’s Faculty of Medicine and Health Sciences to set up the Zebrafish Research Unit just more than a year ago. Several studies are underway involving advanced analytical pharmacology, toxicology, therapeutic target identification and drug discovery. This study is one of the first to stem from the laboratory.