A diet of junk food can lower the IQ of toddlers, a new study has suggested. Scientists say eating habits among three-year-olds could shape their brain performance as they get older.
A diet predominantly high in fats, sugars and processed food at the age of three is directly associated with a lower IQ at the age of eight-and-a-half, according to a Bristol-based study of thousands of British children.
Food packed with vitamins and nutrients notably did the opposite, helping boost mental performance as youngsters got older, the Journal of Epidemiology and Community Health reports.
Researchers said toddlers' diets could change IQ levels later in childhood, even if eating habits improve with age.
"This suggests that any cognitive/behavioural effects relating to eating habits in early childhood may well persist into later childhood, despite any subsequent changes to dietary intake," the authors wrote.
The Avon Longitudinal Study of Parents and Children (ALSPAC) is tracking the long-term health and well-being of around 14,000 children.
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Parents completed questionnaires detailing the types and frequency of the food and drink their children consumed when they were three, four, seven and eight-and-a-half years old.
Every one point increase in the study's dietary pattern score - a record of processed fat intake - was associated with a 1.67 fall in IQ.
The brain grows at its fastest rate during the first three years of life. "It is possible that good nutrition during this period may encourage optimal brain growth," the report added.
Advice for parents
Judy More, a registered paediatric dietician, told Channel 4 News many parents completely under estimate the impact their own eating habits have on their children.
"Some parents will hold their hands up in horror and say they tried to feed their children healthy food but the child refused.
"Parents have to persist. They have to keep eating healthy food themselves and offer it to their children. They have to be quite disciplined.
"It's quite normal for children to go through a fussy eating phase and refuse new food but parents can be reassured they will pass through it.
"Some parents also like to use food as a reward. I would always advise against that as it can develop into comfort eating."
The School Food Trust's director of research, Michael Nelson, said: "Given that around 23 per cent of children start school either overweight or obese, it's absolutely clear that healthy choices as part of their early development will stand children in good stead - not only for keeping a healthy weight as they grow up, but as this evidence suggests, improving their ability to do well at school.
"We know from our own research that giving children healthier food in a decent environment at school improves their concentration in class, suggesting that it isn't just what happens before school that is important for learning.
"But these findings also demonstrate the importance of helping everyone involved with children's early development to get the information and advice they need on good nutrition, to get children excited about food and healthy cooking, and to help families make healthy choices."