Fish oils can transform the behaviour of disruptive teenagers, a study has revealed.
Youngsters were calmer and better able to concentrate after taking daily supplements for three months.
They were also less impulsive and kinder towards their parents, according to the research, which provides the clearest evidence yet of the benefit children receive from fish oils.
The findings add to the evidence that improving children's nutritional intake can calm their behaviour and even boost brainpower.
Case study: 'How fish oil unlocked my son'
The study involved 20 persistently disruptive 12 to 15 year olds at Greenfield Community Arts College, County Durham.
Nineteen were assessed as having moderate or severe attention deficit hyperactivity disorder (ADHD). Nineteen were also judged to have short attention spans while 18 were highly impulsive.
By the end of the 12-week trial, the number showing symptoms of moderate or severe ADHD had dropped to six, while only three were severely inattentive and only six highly impulsive.
The supplements were 'eye q smooth', a blend of Omega 3 and Omega 6, which is supplied by Equazen. Another product cited by the researchers is known as Efalex.
Dr Madeleine Portwood, Durham County Council's senior educational psychologist and lead researcher on the trials, described the results as "stunning".
She said: "These trials were undertaken with a group of potentially vulnerable students with persistent behavioural difficulties and who were at risk of exclusion.
"By taking the fatty acid supplement, those aspects of their behaviour which put them at risk of exclusion improved dramatically."
An earlier trial led by Dr Portwood studied 65 children aged 18 to 30 months.
They were selected for the research from Governmentfunded Sure Start children's centres due to their "challenging behaviour" and problems with attention and concentration.
At the start of the research, almost half of the children were rated as having 'poor' or 'very poor' behaviour.
But after receiving supplements, nine out of ten of these youngsters had improved to moderate or good ratings.
Sixty-six per cent of children at the beginning of the trial had 'poor' or 'very poor' con-centration levels but all improved to moderate or good after five months.
The latest findings emerged amid a scientific row over the extent of the health-giving properties of oily fish.
Mackerel, tuna, herring and other fish rich in omega-3 fatty acids have been thought to reduce the risk of heart disease, strokes and some cancers.
But University of East Anglia researchers analysed 89 studies on the subject and found little evidence to back claims of reduced death rates.
Dr Portwood said last night: "The studies looked at the effect on the blood but we are actually looking at how the brain is working."