A new study from the University of Georgia found that sugar negatively impacts brain development in children. Kids consume sugar more than any other age group, despite warnings about high-sugar diets leading to health problems like obesity. Food companies directly target children in their ads and create sugary products to entice them. While parents could buy other foods for their children, processed foods’ affordability and convenience often outweigh the negatives.

Most people know that high sugar consumption can lead to obesity, heart disease, or diabetes, among other health problems. However, researchers have done few studies on how high-sugar diets in childhood impact brain development. The team wanted to focus their investigation on how sugar affected the hippocampus, a crucial area for learning and memory.

About the study

A University of Georgia faculty member led the research along with a University of Southern California research group. In a rodent model, the study showed that consuming sugary beverages daily during adolescence impairs learning and memory during adulthood. The team also found that changes in gut bacteria could be the culprit behind memory and learning difficulties. The study was published in the journal Translational Psychiatry on March 31.

They found that mice given the bacteria, called Parabacteroides, began to have memory problems during the study. This occurred even if they had never consumed sugar previously.

“Early life sugar increased Parabacteroides levels, and the higher the levels of Parabacteroides, the worse the animals did in the task,” said Emily Noble, assistant professor in the UGA College of Family and Consumer Sciences and first author of the study. “We found that the bacteria alone was sufficient to impair memory in the same way as sugar, but it also impaired other types of memory functions as well.”

How high sugar consumption impairs brain functioning and alters gut bacteria

The Dietary Guidelines for Americans, set by the USDA and U.S. Health and Human Services recommend limiting sugar. It proposes keeping sugar consumption at 10 percent or less of daily calories. However, the Centers for Disease Control and Prevention (CDC) found that Americans aged 9-18 greatly surpass this guideline. The majority of their daily calories come from sugary beverages, unfortunately.

The hippocampus helps with many cognitive functions and doesn’t develop fully until late adolescence. Because of this, researchers wanted to understand better how sugary diets could impact brain development and the gut microbiome.

What the study on high sugar diets and brain health revealed

Juvenile rats consumed their regular diet and an 11% sugar solution, identical to commercially sold sugary drinks. Then, the research team had the rats perform a memory task heavily dependent on the hippocampus. The task specifically measured episodic contextual memory. This is the ability to remember the context where the rats had previously seen a familiar object.

Not surprisingly, the rats given the sugar solution had a more difficult time completing the task.

“We found that rats that consumed sugar in early life had an impaired capacity to discriminate that an object was novel to a specific context, a task the rats that were not given sugar were able to do,” Noble said.

Researchers then had the rats perform another memory task that measured immediate recognition memory. This task didn’t involve the hippocampus and measured the rats’ ability to recognize something they had seen before. In this case, sugar didn’t impact the rats’ recognition memory.

“Early life sugar consumption seems to selectively impair their hippocampal learning and memory,” Noble said.

How a high sugar diet altered gut bacteria in the mice

Further investigation discovered that consuming large amounts of sugar resulted in more Parabacteroides in the gut microbiome. Over 100 trillion microorganisms live in the gastrointestinal tract and have a considerable impact on health.

Researchers wanted to identify exactly how the bacteria impacted memory and learning. To accomplish this, they increased levels of Parabacteroides in the microbiome of rats that had never consumed sugar. These rats showed difficulty completing both hippocampal-dependent and hippocampal-independent memory tasks.

“(The bacteria) induced some cognitive deficits on its own,” Noble said. He said that future research would focus on which specific pathways are involved in gut-brain signaling.