Sugar: Is it bad for kids’ learning and behavior?

Important Points:

  • Sugar
  • Behavior
  • Learning
  • Brain
  • Memory

Sugar: Is it bad for kids’ learning and behavior?

The effect of sugar intake on children’s behavior is a hotly debated topic in pediatrics. Parents and educators often contend that sugar and other carbohydrate ingestion can dramatically impact children’s behavior, particularly their activity levels. Physicians, on the other hand, have looked at controlled studies of sugar intake and have not found hypoglycemia or other blood sugar abnormalities in the children who are consuming large amounts of sugar. So how do sugar and behavior go together?

What effects of sugar make it harmful?

Diets high in refined sugar and saturated fat not only contribute to weight gain and associated health issues, but also have a profoundly detrimental impact on brain function.

It is known that excessive consumption of sugar damages areas of the brain essential for learning and memory processes. Neurons in brain regions, including the hippocampus, that encode memories no longer work efficiently leading to poorer learning.

Recent research in rodents has shown the adolescent brain is at an increased risk of developing diet-induced cognitive dysfunction. Teenage rats that drank sugary beverages were less able to remember a specific location leading to an escape hatch. This was compared to adult rats drinking sugary beverages, and teenage rats that had low-sugar diets.

The brains of the adolescent sugar-diet rats also showed increased levels of inflammation in the hippocampus, disrupting learning and memory function. Inflammation in the brain can contribute to cognitive decline and dementia.

What effect does sugar have on learning?

  • Sugar slows down the brain

2012 study on rats, conducted by researchers at UCLA, found that a diet high in fructose (that’s just another word for sugar) hinders learning and memory by literally slowing down the brain. The researchers found that rats who over-consumed fructose had damaged synaptic activity in the brain, meaning that communication among brain cells was impaired.

Heavy sugar intake caused the rats to develop a resistance to insulin — a hormone that controls blood sugar levels and also regulates the function of brain cells. Insulin strengthens the synaptic connections between brain cells, helping them to communicate better and thereby form stronger memories. So when insulin levels in the brain are lowered as the result of excess sugar consumption, cognition can be impaired.

  • Sugar Decreases Attention Span and Memory

It’s been well documented that sugar activates the brain’s pleasure response, but scientists are discovering that it impacts the brain in a variety of other ways.

When people consume a lot of sugar and then attempt challenging tasks, like math problems, the brain’s hypothalamus allows the body to release a lot of cortisol, or stress hormone, which impedes memory. When children’s bodies are flooded with cortisol at school, they struggle to pay attention to their lessons and find it difficult to sit quietly. When their attention is elsewhere, they find it difficult to retain information they’re taught.

  • Chronic Sugar Consumption Might Permanently Impair Memory Functions

In the short term, sugar consumption will only impair memory temporarily, so if children reduce their consumption, they should find that they can reach their actual academic potential. Some studies suggest that overindulging in sugar early may have a long-lasting effect.

Researchers from the University of Southern California fed adult and adolescent rats beverages with sugar levels comparable to that found in ordinary sodas. After a month, the adults showed normal brain function. However, the adolescent rats showed reduced memory and learning capacity. In addition to reduced memory levels, these rats also had inflamed hippocampi. This part of the brain is crucial for forming memories and organizing and storing memories.

If sugar can impact young rats in this way, what’s it doing to your child?

  • Sugary Foods Crowd Out Brain Food

When sugar moves into the digestive tract, it sends a signal to the brain to tell the body that it’s full. So it makes sense that researchers from Pennsylvania State University have found that the more added sugar children consume, the less likely they are to eat healthy brain foods like grains, vegetables, fruits, and dairy products.

Sugar and moods in children

Extreme levels of sugar in children can cause interference with neurotransmitters responsible for keeping moods stable. This often leads to depression and anxiety in children. Moreover, high sugar levels can cause inflammation of cells in an area of the brain known as hippocampus. This area plays a critical role in organizing and storing memories as well as connecting senses and emotions to those memories.

While this is a topic that’s still controversial, sugar has an addictive effect on children and adults alike. Like drugs, sugar floods the brain with dopamine, a feel good chemical, thus interfering with normal functioning of the brain. A study conducted at Yale University found that simple sight of a milkshake activated the same reward centers of the brain as cocaine does with addicts. In fact, another study conducted in 2007 found that study subjects (rats) preferred sugar water to cocaine.

If you notice behavior changes or mood swings in your child, consider keeping a food journal. Track what they eat and when they exhibit concerning behavior. Try eliminating suspicious foods to see if the behavior changes. While food isn’t the cause of all behavioral issues and conditions, it’s important to make sure that your child is not suffering from something that can be easily remedied.

The teenage brain and sugar

The teenage brain undergoes major developmental changes in terms of structure and function. Brain-imaging studies show that the prefrontal cortex doesn’t fully mature until the early 20s. A major role of the prefrontal cortex is performing executive functions which encompasses behavioral control, attention and decision-making.

Excessive consumption of sugar during adolescence could derail normal brain maturation processes, and may alter normal development trajectories, leading to enduring behavioral predispositions.

Poor regulation of the prefrontal cortex during adolescence can explain the increased risk taking behaviors in teenagers, including dangerous driving, drug use, and binge drinking.

Changes in the brain caused by overconsumption of sugary foods during adolescence can manifest in later life as difficulty in experiencing reward. Research has shown male rats that drank sugar water during adolescence showed reduced motivation and enjoyment of rewards when they were adults. These behaviors are core features of mood disorders including depression. Importantly, this shows that how we eat during adolescence can impact brain function as adults.

How much sugar is OK?

Limiting your child’s sugar intake is essential for helping them achieve their academic potential. The American Heart Association recommends that children have no more than four teaspoons of sugar a day. Children younger than 2 years should have no sugar at all.

While calculating sugar intake, it’s important to note that every 4 grams of sugar equals 1 teaspoon. Also, be aware of the hidden sugars hiding in unexpected places like sauces, dried fruits, and flavored yogurts.

A recent study supports the idea that a breakfast with a lower sugar load may improve short-term memory and attention span at school. Giving your child a breakfast which contains fiber (oatmeal, shredded wheat, berries, bananas, whole-grain pancakes, etc.) instead of loads of refined sugar should keep adrenaline levels more constant and make the school day a more wondrous and productive experience. Packing her/his lunch box with delicious fiber-containing treats (whole-grain breads, peaches, grapes, a myriad of other fresh fruits, etc.) may turn afternoons at home into a delight.


  1. The Conversation (2016):  Why sugar is so much worse for teenagers’ brains. Retrieved from

  • Arizona Ob Gyn Associates (2015):  How Sugar Affects a Childs Brain. Retrieved from
  • The Centre for Parenting Education (2019): Sugar and our children…What’s the deal? Retrieved from

  • Huffpost (2015): This Is What Sugar Does To Your Brain. Retrieved from

  • Verywell Mind (2017):  Negative Impact of Sugar on the Brain. Retrieved from

  • Learning Liftoff (2016): The Effects of Sugar on a Child’s Academic Performance. Retrieved from

  • Dr Greene (2018):  The Relationship between Sugar and Behavior in Children. Retrieved from

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