The three-year £1.6m study is funded by UK Research and Innovation (UKRI) as part of its work to create opportunities and improve outcomes.
Researchers will work with school staff, local councils, caterers, public health experts and politicians across the four parts of the UK, to explore what food is provided and eaten at schools.
It is being carried out in partnership with Public Health Wales, LACA, Newcastle University, Queen’s University Belfast Glasgow Caledonian University and with advice from the Children’s Commissioner for Wales.
The team will work closely with two local authorities in Wales to study the nutritional content of school menus and investigate what is actually consumed by children.
This will create an understanding of whether one of the intentions of the universal free school meals policy - consumption of a healthy, nutritionally balanced meal at primary school - is being realised.
Principal investigator Dr Sara Long, who recently spoke at the LACA Main Event, said: “Many families are struggling with the cost of living. Prices have risen, and often, less healthy food is cheaper and easier to access.
“Children living in the poorest areas often do not eat enough fruits, vegetables, and other foods that make up a healthy balanced diet. School meals are therefore a great opportunity to ensure all children have access to good nutrition.
“But not enough is known about the nutritional content of food offered in schools. Not all children and families choose to take up school meals. For those that do, little is known about food choice and whether children eat the healthier items put on their plates."
The researchers will also interview school staff, parents/carers and children to find out what influences provision, uptake and consumption of school meals.
This data will be used to provide recommendations for improvements to school food provision and uptake, as well as informing strategies to promote healthier choices among children and families.
Professor Kevin Morgan, based at Cardiff University’s School of Geography and Planning, added: “As the only UK nation to have fully rolled out universal free school meals to all state-funded primary schools, Wales is a fitting place to host a UKRI-funded project on the provision, uptake and consumption of universal free school meals.”