In a discovery that will give nutritionists the shivers, a Japanese scientist has discovered that consuming ice cream for breakfast improves a person's alertness and mental performance.

Yoshihiko Koga, a professor at Tokyo's Kyorin University, has carried out a series of clinical trials in which test subjects were required to eat ice cream immediately after waking up.

They were then put through a series of mental exercises on a computer.

Compared to a group that had not eaten ice cream, Prof Koga's subjects exhibited faster reaction times and better information-processing capabilities, the Excite News web site reported.

Monitoring of the subjects' brain activity revealed an increase in high-frequency alpha waves, which are linked to elevated levels of alertness and reduced mental irritation.

To examine the possibility that the test subjects' reactions were simply the result of the brain being shocked into higher levels of alertness by the low temperature of the ice cream, Prof Koga repeated the experiment with cold water instead of ice cream.