IIt's a warning passed down from generation to generation: give your child too many sweets and they'll bounce off the walls. But is there scientific evidence that sugar causes us to go into overdrive? Not yet, says Amanda Avery, associate professor of nutrition and dietetics at the University of Nottingham.
She says there are theories linking sugar to behavioral changes. One of them has to do with the way sugar activates the body's reward system, causing a surge of dopamine, the “feel-good” neurotransmitter. “Increased dopamine levels may be associated with changes in behavior, which may include periods of hyperactivity,” Avery says.
Another theory focuses on how eating large amounts of sugar can cause blood glucose levels to spike and then drop quickly, which is known as reactive hypoglycemia. This can cause changes in behavior, some of which can be interpreted as hyperactivity.
However, there is little evidence to support these theories. Not least because hyperactivity – outside its clinical context as a symptom of attention deficit hyperactivity disorder (ADHD) – is subjective: “What one parent might call hyperactive, another might simply consider energetic.”
Research so far I've only found limited links between sugar consumption and hyperactive behavior, mainly among children already diagnosed with ADHD. The strongest link appears with sweetened drinks containing seven or eight teaspoons of sugar per serving, which also contain additives and caffeine, making it difficult to isolate sugar as the culprit. Some animal (but not human) studies have shown that these fed a high sugar diet at an early age are more likely to exhibit hyperactivity later in life.
So, does sugar make us hyperactive? This has not yet been proven. However, Avery says, most of us eat more sugar than is healthy, and we should try to cut back.
