Researchers in Spain examined levels of children’s “fluid intelligence”, which is the ability to solve reasoning problems and use “working memory” – the ability to retain new information while it is needed in the short term.
The team said their findings suggested healthier diets could have a direct impact on the development of children’s brains.
Lead author Jordi Júlvez, who worked alongside academics at Barcelona’s Institute for Global Health, said: “Organic diets are richer than fast food diets in nutrients necessary for the brain, such as fatty acids, vitamins and antioxidants, which together may enhance cognitive function in childhood.”
Scientists also said factors such as eating junk food, living in overcrowded houses and exposure to domestic tobacco smoke were associated with reduced levels of fluid intelligence.
In addition, exposure to fine particulate matter (PM2.5) indoors was associated with lower working memory scores.
The research team used data from 1,298 children aged 6-11 years from six European countries – the UK, France, Spain, Greece, Lithuania and Norway.
They examined 87 environmental factors the children were exposed to in utero, including air pollution, traffic, noise, various chemicals and lifestyle factors, and another 122 factors they were exposed to during childhood.
They said their aim was to analyse the influence these factors could have on the development and maturation of the human brain.
“During childhood the brain is not yet fully developed for efficient defence against environmental chemicals and is particularly sensitive to toxicity, even at low levels that do not necessarily pose a risk to a healthy mature brain,” the researchers said.
The authors said the research was unique as their method took into account the totality of exposures rather than focusing on a single one. They said this provided a better understanding of the complexity of multiple environmental exposures and their simultaneous effect on children’s brain development.
They noted that there has previously been little research on the relationship between diet and cognitive function, but fast food intake has been associated with lower academic development success and some previous studies have also reported positive associations between organic diets and executive function scores.
“In our study we found better scores in fluid intelligence and working memory with higher organic food intake and lower fast food intake,” said Dr Júlvez.
In contrast, exposure to tobacco smoke and indoor PM2.5 during childhood may negatively affect cognitive function by enhancing pro-inflammatory reactions in the brain, the researchers suggested.
But Dr Júlvez, cautioned that “the number of people living together in a home is often an indicator of the family’s economic status, and that contexts of poverty favour less healthy lifestyles, which in turn may affect children’s cognitive test scores”.
The research is published in the journal Environmental International.