Published in the Journal of Nutrition and Food Sciences, the study involved researchers pulling together the results from 29 randomised controlled trials - the highest quality evidence available.
These trials, all published in the last five years, had involved giving children supplements containing different amounts of fatty acids such as omega-3s and omega-6s.
Of these, 22 studies involving more than 3,000 children revealed significant benefits for learning, focus and behaviour.
Study co-author Dr Emma Derbyshire, a nutritionist who specialises in children's diets, worked alongside a researcher at the University of South Wales to make the finding. She said: "Helping children to learn and focus is a central part of education.
"Given that the human brain is around 60 per cent fat, it's reasonable to assume that the level and type of fats in our bodies will influence brain function and performance.
"Our review clearly showed that improving children's intakes of omega-3 and certain omega-6 fats had a marked beneficial effect on reading ability, spelling, behaviour and attention.
"Conversely, these fatty acid supplements helped to lower hyperactivity and aggression which would tend to put children in a better frame of mind to learn."
She added: "The strongest clinical effects for the fatty acids supplements has been shown with Equazen, which has a formulation clinically proven to provide the functional building blocks our brains need after the age of two.
"Therefore, I believe that getting blood fatty acid levels right could be a vital step in providing learning support to children who are struggling at school."
Last November, a major review of clinical trials concluded that omega fatty acids are an "effective and safe treatment" for children with ADHD.
The condition is a neurodevelopmental disorder characterised by difficulty maintaining attention, impulsive behaviour and extreme hyperactivity.
For the research, published in the Journal of Lipids, 16 studies were analysed.
They included those where omega fatty acids had been a stand-alone treatment and others where they'd been used alongside prescription drugs.
The majority of the studies (13) reported significant improvements in ADHD symptoms, including reduced hyperactivity and impulsivity, better attention, and improved working and short-term memory, when a fatty acid supplement was taken.