Sales of fish, vegetables and other so-called “brain foods” have risen in recent weeks as students seek ways to do better in exams.

UK supermarket Tesco said sales of tuna, cod, plaice and mackerel increased 34% in recent weeks in towns with large student populations. Sales of broccoli, asparagus, spinach and vitamin supplements also increased.

“There’s a growing belief that exam success can, quite literally, be served up on a plate,” Tesco’s fresh produce director, Steve Murrells, was quoted by BBC News Online as saying.

“Students now prepare for their studying in the same way that athletes prepare for their races.

“They are now using a good diet as well as intensive study to help boost performance during this critical time in their academic lives.”

The rise in fish sales was largest in university towns such as Cambridge, Durham, Edinburgh and Oxford.

Fish contains dimethylamino-ethanol, a nutrient which is believed to aid memory.