The saying, “Everything I really need to know I learned in kindergarten” may be truer than you think. Adding to the long list of reasons why good nutrition is important during the preschool years, a new study finds that little kids’ brains need massive amounts of glucose during those pre-K years to develop properly; and that's one big reason why childhood lasts as long as it does.
Glucose is the sole source of energy or fuel for the brain under normal conditions. We get it from consuming carbohydrates found in fruits, vegetables, grains, and dairy foods.
Children grow slowly compared to our non-human animal relatives like chimpanzees, and the reason for that has always been something of a mystery. It was believed that the large amount of energy used by the brain during childhood meant that there was little left over to support body growth, but this had never been proved.
The brain’s maximum glucose usage occurs by the age of five. Kids' brains need a steady stream of glucose since they have no way to store it.
Christopher Kuzawa, lead author of the study and professor of anthropology at Northwestern’s Weinberg College of Arts and Sciences said in a statement, “Our findings suggest that our bodies can't afford to grow faster during the toddler and childhood years because a huge quantity of resources is required to fuel the developing human brain.”
This “brain drain” peaks at the age of four. The brain burns glucose at a rate equivalent to two-thirds of the calories the body uses at rest or greater than 40 percent of total energy expenditure. The brain’s maximum glucose usage occurs by the age of five.
During the preschool years, it can be difficult to figure out how old a child is by their size, according to Kuzawa. He explained that this is because body growth stops at the ages when brain development is occurring rapidly since the brain is using all of the available energy.
“As humans we have so much to learn, and that learning requires a complex and energy-hungry brain,” said Kuzawa. “The mid-childhood peak in brain costs has to do with the fact that synapses, connections in the brain, max out at this age, when we learn so many of the things we need to know to be successful humans.”
The study is published in the Proceedings of the National Academy of Sciences.