The key seemed to be the diet at age 3, since diet at 4 and 7 seemed to have no effect on IQ, the research team noted. However, to truly understand the effect of diet on children's intelligence, further studies are needed, they said.
Commenting on the study, Samantha Heller, a dietitian, nutritionist and exercise physiologist in Fairfield, Conn., said that "most of us do not realize that the foods we eat have direct consequences on brain growth, function and performance."
When a child's diet consists primarily of high-calorie foods that are low in the nutrients they need (such as healthy fats, vitamins and minerals), their brains don't get the compounds necessary to develop and function properly, Heller said. "This can have a series of deleterious effects, including decreased cognitive ability, poor behavior and social skills," she said.
"Fast and junk food seem like an easy and affordable option for busy parents, but defaulting to high-fat, high-sugar, high-calorie foods is putting their children's health and future at risk," Heller said.
Cooking easy, healthy meals for the family will give "children's brains a boost in essential nutrients needed for healthy development and improved cognitive skills," she added.
For more information on healthful eating for kids, visit the U.S. Department of Agriculture.
SOURCES: Kate Northstone, Ph.D., research fellow, department of social medicine, University of Bristol, Bristol, England; Samantha Heller, M.S., R.D., dietitian, nutritionist, exercise physiologist, Fairfield, Conn.; Feb. 7, 2011, Journal of Epidemiology and Community Health
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