The authors report that a diet composed primarily of processed foods at the age of 3 is directly associated with a lower IQ at the age of 8 1/2, the Guardian reports.
From these results, derived from a long-term study of around 14,000 British children, the researchers conclude that the eating habits of 3-year-old children shape their brain performances as they get older.
Strikingly, every one-point increase in the studys dietary pattern score a record of the childs processed fat intake was associated with a 1.67-point drop in IQ.
Conversely, the authors report food packed with vitamins and nutrients help boost mental performance, the Guardian reports.
The researchers also suggest toddlers poor eating habits could still affect IQ later in childhood, even if the childs eating habits improve with age, according to the newspaper.
The brain grows at its fastest rate during the first three years of life, the Guardian reports, which could account for the findings.
It is possible that good nutrition during this period may encourage optimal brain growth, the authors write.
Michael Nelson, director of research for the U.K.s School Food Trust, tells the Guardian the study makes it clear that healthy food choices during a childs early development are not only important for fighting obesity, but also for improving a kids ability to do well in school.
These findings also demonstrate the importance of helping everyone involved with childrens early development to get the information and advice they need on good nutrition, Nelson adds.