After controlling for every socioeconomic factor they could think of, researchers found that young children with diets heavy in processed foods grew to have lower IQs than similar children who ate more healthily, The Week writes:
Researchers at England’s University of Bristol found that a child’s eating habits at age 3 may influence his cognitive abilities at age 8. Toddler diets high in fat and sugar were associated with lower IQ scores, while healthier eating was tied to higher scores. The report, which appears in the Journal of Epidemiology and Community Health, is being billed as “the first study to suggest a direct link between the diet of young children and their brainpower” years later.
The researchers examined data on nearly 4,000 children born in the early 1990s, including detailed information from parents on what the kids ate and drank at specific ages. It also included the results of IQ tests performed when the children were 8.5 years old. The researchers sorted the kids into three categories based on whether they were given a “processed” diet full of fat and sugar; a “traditional” diet of “meat, potatoes, bread and vegetables”; or a “health-conscious” diet heavy on salad, fruit, rice, and fish. They also rated the kids’ diets on a point scale, “which ranged from minus two for the most healthy to 10 for the most unhealthy.”
At age 8.5, the kids who’d been fed the worst diet as toddlers had slightly lower IQs than the kids with the healthiest eating habits. Every one-point increase in the 12-point unhealthy food scale was associated with a 1.67-point drop in IQ. That correlation held even after researchers adjusted the data for other factors like socioeconomic status and parental education. Improving a child’s diet after age 3 did not seem to correlate to a jump in IQ.