The Golden State Warriors’ Leandro Barbosa works like a horse. As such, he also medicates like one. He admitted last week that his 13-season career is the result of intense training, clean eating, and drinking a thick green liquid normally served up to injured horses in his home country. He swears it’s responsible for his his rapid recovery from ACL surgery in 2012. So, is Barbosa a victim of modern-day quackery, or has he found the real-life Secret Stuff, the equine key to recovery? We might never know: His “Amazonian potion,” extracted from the leaves of a shrub locally known as arnica do mato, is virtually unknown and unavailable in the United States.

If you really want to try Barbosa’s throat-burning horse potion, which has been variously described by his teammates and peers as “vomit-inducing,” “disgusting,” and tasting of “acid,” your best bet is to go to the source: Brazil. There, you’re likely to find arnica do mato leaves alongside other medicinal plants in open-air markets, where it’s mashed up and applied as a poultice or distilled into extracts and smeared directly onto the skin to treat pain, swelling, arthritis, scrapes, and bruises. Local pharmacists prescribe it as a topical treatment for hematomas, blood clots that form inside the body.

Lychnophora ericoides is one of many plants referred to as "arnica do mato."

If it seems like Barbosa’s magic shrub does everything, that’s probably because the local term seems to refer to several different plants. Rigorous science, this is not. Ask for arnica do mato at a local market and you might get leaves from the shrub Lychnophora eriocoides, which the New York Times identified, but you might, alternatively, get Solidago chilensis, Chromolaena maximilanii, or Chromolaena odorata, as one Brazilian pharmacology study pointed out. Arnica do campo, Arnica do mato, Brazilian arnica, and Arnica-brasileira all seem to refer to a group of related plants, lumped together because of their similar healing properties.

Its effects certainly sound promising, but the science to back it up is scarce. Stateside, many naturopaths, including the faculty at the Maryland University of Integrative Health and the president of the American Herbalist Guild, have not even heard of arnica do mato or the plants associated with the term. The FDA has, likewise, not acknowledged its existence. This is why Barbosa has to have his horse-grade plant extracts shipped to him directly from Brazil.

Arnica montana, a relative of Barbosa's shrub, is FDA approved as a treatment for bruising and swelling.

But the government agency has approved a related plant — arnica montana — for use in over-the-counter drugs. It’s not that closely related to the arnica do mato subtypes, but it does have similar effects on soreness, bruising, and swelling. In addition to being an ingredient in natural pain relief gels and creams, arnica montana is listed, sure enough, in the components of many horse care products available in the U.S. In “Sore No More Liniment and Back Brace For Horses,” arnica montana is used as a “cooling” liniment and “stimulating and refreshing body brace,” a sort of aftershave for horses. Ezee Arnica, for horse wounds and scuffs, contains a tincture of the plant. For the most part, it is not ingested, whether by humans or horses. And when it is, it goes down in pill form.

How arnica montana’s effects compare to those of Barbosa’s special shrub remain to be seen. We don’t know much about arnica do mato, but it doesn’t appear to be for the faint of heart — at least, not the way Barbosa takes it. “I don’t do that,” Anderson Varejao, a fellow Brazilian and Golden State Warrior, said when asked whether he imbibes his teammate’s green juice. Barbosa, meanwhile, sucks it down twice a day, bathes in it, and is en route to his second NBA championship at the age of 33. To play like a horse, maybe you have to train like a horse.

Photos via Getty/Doug Pensinger