The Russian Football Union warned players today against drinking “exotic tea” or smoking shisha pipes as it tries to avoid any doping cases ahead of its home World Cup.

In a guide to help players avoid failing drug tests by accident, the RFU says players should be wary of accidentally consuming banned substances.

It recommends players always read the label on exercise supplements and check online whether they’re contaminated with banned products.

The RFU also advises players “not to consume exotic tea,” to avoid smoking shisha and to be wary of possibly contaminated meat from China or South America.

It wasn’t immediately clear what prompted the tea warning. An Algerian player was banned after a 2015 positive test for cocaine he said he accidentally consumed via a friend’s shisha pipe.

The Russian guide comes as Fifa investigates allegations that positive drug tests in Russian football in previous years were covered up. Deputy Prime Minister Vitaly Mutko said last month Fifa is investigating current Russia international Ruslan Kambolov.

Mutko said the case was “not linked to the national team.”

There is also an investigation into Ivan Knyazev, a former defender with the Russia Under-21 team, Mutko told the Tass state news agency at the time. Both players “have given evidence and we’ll see where it goes,” Mutko said.

Russia has been rocked by multiple doping tests across many sports in recent years and accused of a state-sponsored cover-up. The government denies ever supporting drug cheats.