Two thirds of middle school pupils in Shanghai are taking tonics to boost their memories, according to a poll.

Most of their parents told researchers they knew the tonics would not work miracles, but thought they were worth taking anyway.

The China Daily, quoting the Shanghai Evening Post, says parents thought the concoctions might help a little.

Tonics which claim all manner of benefits are widely sold in China.

Authorities last year found more than 1,000 different tonics being sold, but only 20% had state permission to be produced and sold.