A fascinating study conducted by Japanese researchers just published in PLoS One (Public Library of Science) demonstrates a significantly larger brain volume and a higher IQ in healthy children depending on whether their breakfast staple was rice or bread. The authors state:
“Childhood diet is important for brain development. Furthermore, the quality of breakfast is thought to affect the cognitive functioning of well-nourished children. To analyze the relationship among breakfast staple type, gray matter volume, and intelligence quotient (IQ) in 290 healthy children, we used magnetic resonance images and applied voxel-based morphometry.”
They divided their study groups into those children who consumed rice, bread or both as their breakfast staple, controlled for a range of dietary, biological and socioeconomic variables, and analyzed the data.
“We showed that the rice group had a significantly larger gray matter ratio (gray matter volume percentage divided by intracranial volume) and significantly larger regional gray matter volumes of several regions, including the left superior temporal gyrus…The perceptual organization index (POI; IQ subcomponent) of the rice group was significantly higher than that of the bread group.”
Their study didn’t investigate what would be the underlying causes of such a difference, but they speculated that glycemic index may play a role:
“Although several factors may have affected the results, one possible mechanism underlying the difference between the bread and the rice groups may be the difference in the glycemic index (GI) of these two substances; foods with a low GI are associated with less blood-glucose fluctuation than are those with a high GI.”
However, the glycemic index of both rice and bread is relatively high compared to eggs. Drawing on a large body of published research, we can rationally advance the idea that gluten may be the decisive factor in the documented differences in brain volume and IQ. It is difficult to argue with their conclusion:
“Our study suggests that breakfast staple type affects brain gray and white matter volumes and cognitive function in healthy children; therefore, a diet of optimal nutrition is important for brain maturation during childhood and adolescence.”