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

December 17, 2020

Important Points:

Sugar
Behavior
Learning
Brain
Memory

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

Yes. Excess sugar hurts children’s learning. It inflames the hippocampus, the brain’s memory center. It slows communication between brain cells. It raises cortisol, which makes it harder to pay attention and sit still in class. In the short term, the memory effect reverses when sugar comes down.

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How sugar affects children’s behavior is a hotly debated topic in pediatrics. Parents and teachers often say sugar and other carbs can dramatically impact children’s behavior, especially how active they are. Doctors, on the other hand, have looked at controlled studies of sugar intake. They have not found hypoglycemia or other blood sugar problems in children who eat 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. They also have a profoundly detrimental impact on brain function.

Eating too much sugar is known to damage parts of the brain that are key for learning and memory. Neurons (brain cells) that encode memories, in regions including the hippocampus, no longer work efficiently. This leads to poorer learning.

Recent research in rodents has shown that the teen brain is at higher risk of diet-induced cognitive dysfunction. Teenage rats that drank sugary drinks were less able to remember a specific spot that led to an escape hatch. They were compared with adult rats drinking sugary drinks, and with teenage rats on low-sugar diets.

The brains of the teen rats on the sugar diet also showed more inflammation in the hippocampus. That inflammation disrupted learning and memory. Inflammation in the brain can contribute to cognitive decline and dementia.

What effect does sugar have on learning?

Sugar slows down the brain

A 2012 study on rats by UCLA researchers found that a diet high in fructose (a form of sugar) hinders learning and memory. It does this by literally slowing down the brain. Rats that ate too much fructose had damaged synaptic activity in the brain. That means communication among brain cells was impaired.

Heavy sugar intake caused the rats to develop resistance to insulin. Insulin is a hormone that controls blood sugar levels. It also regulates how brain cells work. Insulin strengthens the synaptic connections (links) between brain cells. This helps them communicate better and form stronger memories. So when insulin levels in the brain are lowered as a result of excess sugar, cognition (thinking) can be impaired.

Sugar Decreases Attention Span and Memory

It’s well documented that sugar activates the brain’s pleasure response. But scientists are finding that it affects the brain in many other ways too.

When people eat a lot of sugar and then try hard tasks, like math problems, the brain’s hypothalamus lets the body release a lot of cortisol, the stress hormone, which impedes memory. When children’s bodies are flooded with cortisol at school, they struggle to pay attention to their lessons. They find it hard to sit quietly. When their attention is elsewhere, they find it hard to retain what they are taught.

Chronic Sugar Consumption Might Permanently Impair Memory Functions

In the short term, sugar will only harm memory for a while. So if children eat less sugar, 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 gave adult and teen rats drinks as sugary as ordinary sodas. After a month, the adults showed normal brain function. But the teen rats showed weaker memory and learning. Along with weaker memory, these rats also had inflamed hippocampi. This part of the brain is key for forming, 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 signals the brain that the body is full. So it makes sense what researchers from Pennsylvania State University found. The more added sugar children eat, 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 interfere with neurotransmitters (chemical messengers in the brain) that are responsible for keeping moods stable. This often leads to depression and anxiety in children. High sugar levels can also cause inflammation of cells in a part of the brain called the hippocampus. This area plays a key role in organizing and storing memories. It also connects senses and emotions to those memories.

This topic is still controversial, but sugar has an addictive effect on children and adults alike. Like drugs, sugar floods the brain with dopamine, a feel-good chemical. In this way, it interferes with normal brain function. A study at Yale University found that just the sight of a milkshake activated the same reward centers of the brain that cocaine does in addicts. In fact, another study done 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 show concerning behavior. Try cutting out suspect foods to see if the behavior changes. Food isn’t the cause of all behavioral issues and conditions. Still, it’s important to make sure your child is not suffering from something that can be easily remedied.

The teenage brain and sugar

The teenage brain goes through major changes in structure and function as it develops. Brain-imaging studies show that the prefrontal cortex doesn’t fully mature until the early 20s. A major job of the prefrontal cortex is executive function. That includes behavioral control, attention and decision-making.

Eating too much sugar in the teen years could derail the way the brain normally matures. It may also change the normal path of development and lead to lasting behavioral predispositions (tendencies).

Poor control of the prefrontal cortex in the teen years can explain the increased risk-taking in teenagers. This includes dangerous driving, drug use, and binge drinking.

Brain changes caused by eating too many sugary foods in the teen years can show up later in life. They show up as trouble experiencing reward. Research has shown that male rats that drank sugar water as teens showed reduced motivation and less enjoyment of rewards as adults. These behaviors are core features of mood disorders, including depression. Importantly, this shows that how we eat as teens can affect 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.

When you add up sugar intake, note that every 4 grams of sugar equals 1 teaspoon. Also watch for hidden sugars in unexpected places like sauces, dried fruits, and flavored yogurts.

A recent study supports this idea: a breakfast with less sugar may improve short-term memory and attention span at school. So give your child a real-food breakfast (eggs, plain yogurt, berries, bananas, etc.) instead of loads of refined sugar. Skip refined grains such as cereal, pancakes and white bread. This should keep adrenaline levels more steady. It should also make the school day more wondrous and productive. Pack her/his lunch box with tasty fiber-containing treats (peaches, grapes, a myriad of other fresh fruits, etc.). That may turn afternoons at home into a delight.

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