LIBREVILLE, Gabon - Some in Gabon believe the bitter iboga root comes from the Tree of Knowledge in the Garden of Eden. Others elsewhere have derided it as a dangerous drug.
Today a growing number of Westerners are travelling to the central African country to sample it themselves as part of an ancestral rite called Bwiti, one of Gabon's official religions.
Among them is Remy Causse, who at 45 made the long journey from France in hopes that the ritual would help him to "see more clearly".
Bwiti combines worship of ancient forest spirits with elements of Christianity. It is practiced regularly and involves ingesting the powerful psychoactive root, iboga, which has effects similar to LSD, mescaline or amphetamines.
"Iboga cleans the insides," says Tatayo, a French-Gabonese spiritual guide who receives many of the Western "bandzi", or candidates for initiation.
"The bandzi empties himself of everything bad that is buried inside before coming face to face with himself." But the deaths, deemed accidental, of two Western initiates saw the practice come under sharp scrutiny, notably in former colonial power France where health officials warned it was "hallucinogenic and highly toxic".
A report by the Mission of Vigilance against Sectarian Abuses (Miviludes) from 2007 called Bwiti a form of cult ritual that is dangerous "both physically and mentally".
Tatayo himself concedes that "you must be closely watched when you ingest iboga".
But Bwiti shamans like Tatayo believe that when they eat iboga, they are granted the power to see the future, heal the sick and speak with the dead.
Users say it helps them to break away from negative habits, and an extract from the root is now being used in Western medicine to treat drug addicts and alcoholics.
Like many foreigners before him, Causse turned to "Tatayo", who is originally from southwest France, at his beachside concession next to the president's quarters in Gabon's capital Libreville.