Children who eat a healthy breakfast before starting the school day achieve better academic results than pupils who do not, according to a study released last week.
Public health experts at Cardiff University in Britain said their findings provide the strongest evidence yet of a direct and positive link between eating breakfast and educational attainment.
Their report, published in the journal Public Health Nutrition, suggests that the odds of achieving an above-average score in tests at the age of 11 were up to twice as high for pupils who ate breakfast, compared with those who did not.
There is already substantial research into the links between eating breakfast and measures of concentration and focus; this is the first to show a "meaningful" link between eating breakfast and concrete measures of academic attainment, the authors said.
The Cardiff study, which tracked 5,000 nine- to 11-year-olds from more than 100 Welsh primary schools, adds to a growing body of evidence showing that effective interventions to improve pupils' health is likely to improve their academic performance.
Said lead author Hannah Littlecott: "While breakfast consumption has been consistently associated with general health outcomes, and acute measures of concentration and cognitive function, evidence regarding links to concrete educational outcomes has, until now, been unclear.
"This study offers the strongest evidence yet of links between aspects of what pupils eat and how well they do at school, which has significant implications for education and public health policy."
She said schools may view dedicating time and resources towards improving child health as "an unwelcome diversion from their core business of educating pupils". However, embedding health improvements into this core business might also deliver educational improvements, said Ms Littlecott, whose work focuses on the development and evaluation of complex interventions for public health improvement.
Schoolchildren who took part in the study were asked to list, in order, all the food and drinks they had consumed over a period of over 24 hours, from breakfast the day before to breakfast the day they made their food lists.
The children's breakfast eating habits were linked to their scores in teacher assessments (carried out six to 18 months after the questionnaire), which are used to measure children's academic attainment at the end of primary school in Wales.
Researchers found that eating a good breakfast - made up of dairy, cereal, fruit and bread - could improve educational performance. Eating unhealthy items, such as sweets and crisps - which was reported by one in five children - had no positive impact on academic results.
Professor Chris Bonell, who specialises in sociology and social policy at the University College London Institute of Education, said: "Many schools throughout the UK now offer their pupils a breakfast. Ensuring that those young people most in need benefit from these schemes may represent an important mechanism for boosting the educational performance of young people."
According to 2012 figures, almost half of schools in England already provide breakfast clubs for pupils, particularly in areas of deprivation. In Wales, there is a free breakfast initiative for primary schools.
For instance, Magic Breakfast, a charity providing free breakfasts to more than 22,000 children a day, said all children should have access to a healthy breakfast at the start of the school day.