The study was led by the University of East Anglia (UEA) Health and Social Care Partners in collaboration with Norfolk County Council and is the first of its kind to investigate such factors. Despite widely accepted knowledge that eating plenty of fresh fruit and vegetables contributes to physical wellbeing, ie a healthy body, research into mental wellbeing has been lacking. Given the increased prevalence of poor mental health among young adults and children, the cohort recognised that investigating causative factors is vital.

The research team reported that higher consumption of fruit and vegetables corresponded with better wellbeing, particularly among secondary school pupils. Children who ate five or more portions of fruit and veg a day had the highest scores for mental wellbeing.

The study involved data from almost 9,000 children in 50 schools across Norfolk in the UK (7,570 secondary and 1,253 primary school children) taken from the Norfolk children and Young People’s Health and Wellbeing Survey.

This survey was commissioned by the Public Health department of Norfolk County Council and the Norfolk Safeguarding Children Board. It was open to all Norfolk schools during October 2017.

Children involved in the study self-reported their dietary choices and took part in age-appropriate tests of mental wellbeing that covered cheerfulness, relaxation, and having good interpersonal relationships.

Lead researcher Prof Ailsa Welch, from UEA’s Norwich Medical School, said: “In terms of nutrition, we found that only around a quarter of secondary-school children and 28 per cent of primary-school children reported eating the recommended five-a-day fruits and vegetables. And just under one in ten children were not eating any fruits or vegetables.

“More than one in five secondary school children and one in 10 primary children didn’t eat breakfast. And more than one in 10 secondary school children didn’t eat lunch.

secondary school children who drank energy drinks for breakfast had particularly low mental wellbeing scores, even lower than for those children consuming no breakfast at all.

The team looked at the association between nutritional factors and mental wellbeing, taking account of other factors that might have an impact – such as adverse childhood experiences and home situations.

Dr Richard Hayhoe, also from UEA’s Norwich Medical School, said: “We found that eating well was associated with better mental wellbeing in children. And that among secondary school children in particular, there was a really strong link between eating a nutritious diet, packed with fruit and vegetables, and having better mental wellbeing.

“We also found that the types of breakfast and lunch eaten by both primary and secondary school pupils were also significantly associated with wellbeing.

“Children who ate a traditional breakfast experienced better wellbeing than those who only had a snack or drink. But secondary school children who drank energy drinks for breakfast had particularly low mental wellbeing scores, even lower than for those children consuming no breakfast at all.

“According to our data, in a class of 30 secondary school pupils, around 21 will have consumed a conventional-type breakfast, and at least four will have had nothing to eat or drink before starting classes in the morning.

“Similarly, at least three pupils will go into afternoon classes without eating any lunch. This is of concern, and likely to affect not only academic performance at school but also physical growth and development.

Highlighting the decisive role that diet plays in children’s wellbeing, Dr Hayhoe continued: “Another interesting thing that we found was that nutrition had as much or more of an impact on wellbeing as factors such as witnessing regular arguing or violence at home.

Prof Welch commented: “As a potentially modifiable factor at an individual and societal level, nutrition represents an important public health target for strategies to address childhood mental wellbeing.”