Food and Behaviour Research

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Enhanced adrenomedullary response and increased susceptibility to neuroglycopenia: mechanisms underlying the adverse effects of sugar ingestion in healthy children

Jones TW, Borg WP, Boulware SD, McCarthy G, Sherwin RS, Tamborlane WV. (1995) J Pediatr 126(2) 171-7. doi: 10.1016/s0022-3476(95)70541-4. 

Web URL: View this and related abstracts via PubMed here

Abstract:

Objective: 

Eating simple sugars has been suggested as having adverse behavioral and cognitive effects in children, but a physiologic mechanism has not been established. This study was performed to address this issue.

Design: 

Metabolic, hormonal, and symptomatic responses to a standard oral glucose load (1.75 gm/kg; maximum, 120 gm) were compared in 25 healthy children and 23 young adults, and the hypoglycemic clamp, together with measurements of P300 auditory evoked potentials, was used to assess whether children are more vulnerable than adults to neuroglycopenia.

Setting: 

Children's Clinical Research Center, Yale University School of Medicine.

Results: 

Baseline and oral glucose-stimulated plasma glucose and insulin levels were similar in both groups, including the nadir glucose level 3 to 5 hours after oral administration of glucose (3.4 +/- 0.1 mmol/L (61 +/- 1.8 mg/dl) in children and 3.5 +/- 0.1 mmol/L (63 +/- 1.8 mg/dl) in adults).

The late glucose decrease stimulated a rise in plasma epinephrine levels that was twofold higher in children than in adults (2260 +/- 289 vs 1031 +/- 147 pmol/L (407 +/- 52 vs 186 +/- 26 pg/ml), p < 0.01) and a significant increase in hypoglycemic symptom scores in children (p < 0.01), but not in adults.

During control experiments, in which six of the healthy children ingested a sugar-free drink, there were no significant changes in plasma glucose levels, hormone concentrations, or hypoglycemic symptom scores.

During the hypoglycemic clamp, P300 potentials did not change in any of eight adult subjects until the plasma glucose concentration was lowered to 3.0 mmol/L (54 mg/dl), whereas similar changes in P300 potentials were observed in six of seven children at glucose levels 3.6 to 4.2 mmol/L (65 to 75 mg/dl).

Conclusion: 

Enhanced adrenomedullary responses to modest reductions in plasma glucose concentration and increased susceptibility to neuroglycopenia may be important contributing factors to adverse behavioral and cognitive effects after sugar ingestion in healthy children.

FAB RESEARCH COMMENT:

This study investigated how a dose of sugar affected blood sugar regulation in healthy adults and children, and also examined the links beween blood sugar and cognition using objective measures of attention by recording brain electrical activity.

Adults and children both showed similar increases in blood glucose, and the release of insulin, following sugar ingestion. However, as blood glucose levels then fell, the resulting release of adrenaline (epinephrine) was twice as great in the children as it was in the adults. Consistent with this, the children also showed more symptoms of hypoglycemia (low blood sugar) than adults.

As blood sugar levels fell, brain electrical activity measures showed that the children's attentional responses also began to fail at higher blood sugar levels than those of the adults.

These findings suggest that children are more sensitive than adults to the effects of sugar on brain function - releasing more adrenaline in response to falling blood glucose levels, and showing greater impairments in objective measures of attention.

As the authors note, these findings could help to explain some of the adverse behavioural and cognitive effects attributed to sugar consumption even in healthy children, as well as in many children with ADHD or related behaviour and learning difficulties.

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