VATICAN CITY (AP) — Bolivian President Evo Morales has again raised eyebrows with an unusual gift for Pope Francis: books about the health benefits of coca leaves.

Morales met with Francis Friday before attending a Vatican conference on social and economic justice. U.S. Democratic presidential candidate Bernie Sanders is also among those attending.

During the audience, Morales presented Francis with three books: “Coca, a bio-bank,” ”Coca, citogenic diet” and “Coca, the anti-obesity factor.”

Morales sparked a minor diplomatic incident during Francis’ 2015 visit to Bolivia by giving the pope a crucifix fashioned as a communist-style hammer and sickle, although Francis said he wasn’t offended.

Coca leaf, the raw material for cocaine, is widely chewed in the Andes to fight against altitude sickness and as a mild stimulant.

Ironically, Francis has been an outspoken critic of the drug trade, especially in his native Latin America.

During a visit to Mexico in February, for instance, the pontiff described drug traffickers as “those who stand before God with their hands drenched in blood, though with pockets filled with sordid money and their consciences deadened.”