University of Bristol's School of Social and Community Medicine suggest that a diet of sugary and fat packed processed food may lower intelligence.

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The study, published in the Journal of Epidemiology and Community Health, bases its findings on participants in the Avon Longitudinal Study of Parents and Children (ALSPAC), which tracks the long term health and well being of around 14,000 children born in 1991 and 1992.

Parents were asked to complete questionnaires, detailing the types and frequency of the foods and drinks their children consumed when they were 3, 4, 7 and 8½ years old. The information was then analysed for three basic diets  “processed” or those high in fats and sugars, “traditional” high in meat and two vegetables, and “health conscious” high in salad, fruit and vegetables, rice and pasta.  

The researchers then measured the intelligence quotients (IQ's) of the children at 8½ and found that, toddlers fed a processed food based diet had lower IQ’s at 8½.  

 "Our research suggests that any cognitive/behavioural effects relating to eating habits in early childhood may well persist into later childhood, despite any subsequent changes (including improvements) to dietary intake,” says Dr Kate Northstone, Research Fellow in the School of Social and Community Medicine.

According to Bristol University’s research, it appears that, whether or not, a child’s diet improves measurable intelligence falls. On the other hand, a healthy diet was associated with a higher IQ at the age of 8½.  

“It is possible that good nutrition during the first three years of life may encourage optimal brain growth, advocating further research to determine the extent of the effect early diet has on intelligence,” added Dr Pauline Emmett, Senior Research Fellow in the School of Social and Community Medicine.

Student information

Previous ALSPAC research suggests that the brain grows fastest during the first three years of life which indicates that head growth is linked to intellectual ability.  The research by Bristol University’s School of Social and Community Medicine appears to support this view.

IQ was measured using a validated test (the Wechsler Intelligence Scale for Children) when they were 8½ years old.  While the longitudinal study tracked 14,000 subjects the complete data was available for just 4,000 children.