Moscow (AFP) - Russia's World Cup team was told to stay away from "exotic teas" and foreign medicine to avoid testing positive for doping during this year's final.
The Russian Football Union issued the recommendations in a series of tweets that also included instructions to be careful with meat from Latin America and China.
"We are proud that Russian football players did not test positive once in the past four years," the RFU said.
"It is very important to stay completely clean."
It was not immediately clear why the football federation was using Twitter to publish rules meant to keep players from being banned for cheating.
Russia will host the World Cup for the first time from June 14 to July 15.
Its preparations have been shadowed by a doping scandal that resulted in Russians competing under the Olympic flag at this year's Winter Games in South Korea.
Russia has furiously denied charges of running a state programme that helped athletes stay clean before and during the 2014 Winter Games in Sochi.
The saga has had wider implications for the World Cup.
Deputy Prime Minister Vitaly Mutko was forced to resign as football federation president and step away from tournament preparations after being handed a lifetime Olympic ban in December.
He struck a defiant note in an interview published on Friday.
Mutko said he was still actively involved in the World Cup and other aspects of Russian football despite his removal from the sport.
"Of course I did not walk away (from football). I still meet people, follow things and help out," he told the Championat.ru sports site.
Mutko explained that he was not allowed to "sign documents or chair executive committee meetings.
"But the most important thing for me now is preparations for the World Cup and of the Russian team for the tournament."
The global football governing body FIFA will be in charge of all testing procedures in Russia.
It will fly the samples to its Swiss labs for analysis because the Russian Anti-Doping Agency (RUSADA) has been stripped of accreditation.
The RFU's guidelines to players effectively removed it from responsiblity for any positive tests.
One of the tweets said a list of banned substances published by RUSADA only covered medicine and food additives registered in Russia.
A drug's absence "does not automatically mean that it is allowed," the RFU said.
It said some herbal teas and even meat may have chemicals that produce positive doping samples.
But it did not identify which of the "exotic teas" were not safe to drink.