DO all those birthday party lollies turn kids into little monsters? Many parents say yes, but the sugar high may be a myth, writes a childless Karen Ravn.

"I have mothers tell me their child can ingest something sweet, and they know to the minute when the reaction is going to occur," says Jo Ann Hattner, a registered dietitian who teaches nutrition at the Stanford University School of Medicine in the US.

Yet the truth is that experts disagree about whether the sugar high and sugar crash truly exist.

Many say the evidence contradicts such stories. "There is no scientific basis to the idea that sugar and/or candy has any major effect on children's behavior, particularly if they eat OK," says Dian Dooley, professor of human nutrition, food and animal sciences at the University of Hawaii at Manoa.

Others think sugar has plenty of skeletons in its closet. "The bottom line is that the ingestion of too much high-glycemic carbohydrate causes a rapid rise and then fall of blood sugar," says Dr. David Ludwig, professor of pediatrics at Harvard Medical School and director of the Optimal Weight for Life program at Children's Hospital Boston. "This triggers a series of metabolic and hormonal changes that can affect appetite and behavior for hours to come."
Still more experts think that the experience of a sugar high is real. But only because parents are convinced it exists.
"I would never try to convince parents the sugar high doesn't exist," says Dr. Thomas Robinson, professor of pediatrics at Stanford and director of the Center for Healthy Weight at Lucile Packard Children's Hospital. "You can't tell them it doesn't happen because, for them, it does happen."
A little basic physiology implies that sugar highs could happen. Glucose, a digestive byproduct of the sugar we eat, is one of the body's two main sources of energy (along with fat). So it seems feasible that eating a lot of sugar could give a person a quick energy boost.
That's the reasoning behind, say, marathoners eating candy bars en route. It's also the theory behind an old test doctors once got a kick out of: They'd give a pregnant woman a glass of orange juice, Hattner says, and in no time, if the woman's baby was healthy, it would be treating its mom like a soccer ball.
But the body is designed to keep glucose levels in the blood stable. When the levels increase, the pancreas releases insulin, which moves glucose out of the blood and into tissues throughout the body.
If levels have spiked steeply, the pancreas might overreact and release too much insulin, so the glucose level could end up dipping below where it should be. But then the pancreas releases another hormone, glucagon, which moves glucose stored as glycogen out of the liver to bring the levels back up again.