Students given omega 3 fish oil supplements in the run up to their GCSE exams recorded their school's best ever results, according to a pilot study.
Omega 3 is found in oily fish such as mackerel
More than 200 students at Fleetwood Sports College, Lancashire, took part in a school-organised study.
"I am not saying omega 3 is responsible for all of the success but it did play a role," said the school's Deputy Headteacher Amanda Howarth.
Students took one capsule a day for 12 weeks prior to their exams.
Nutritionists say children and teenagers need omega 3 fatty acids which are found in oily fish, but more than half of the youngsters at the Fleetwood school never ate fish in their weekly diet.
"It's ironic but that is the same level as national figures," said Ms Howarth, who asked to take part in the trial after reading of behaviour improvements in primary schoolchildren who took omega 3 supplements."
The school's results were analysed by GP Dr Amanda Kirby, from the Dyscovery Centre, Cardiff which studies child learning.
"The results of this trial have also highlighted the need for further investigation into the role of omega 3 in an educational context looking at academic measures," she said.
The study also took a detailed look at 23 students - seven boys, 16 girls - and found they recorded a 79% improvement in reading and spelling after 12 weeks.
The biggest improvements were among girls.