This review, published initially in the Health Research Institute Quarterly, was written by Dr. William Walsh and is reprinted with permission.
When a double-blind experiment studying the effects of sugar on behavior and cognitive ability was published in the New England Journal of Medicine, great publicity accompanied the event with a flood of news reports that the study “conclusively proved that sugar has no significant effect on children’s behavior or academics.”
I read this journal article with great skepticism, since the authors’ conclusions were contrary to our clinical experience involving thousands of children. To my surprise, I discovered that the study was well designed, properly controlled, and very carefully conducted. Moreover, the study’s data provide valuable new information regarding the effect of sugar on children.
The only defect in the study seems to be the authors’ conclusion, which is outrageously broad and unsupported. “Even when intake exceeds typical dietary levels, neither dietary sucrose nor aspartame affects children’s behavior or cognitive function.” It is unfortunate that the authors failed to qualify their conclusion properly, to correspond to obvious limitations.
The study involved two cohorts of children studied concurrently-23 children of ages 6 to 10 years reported by their parents to respond adversely to sugar, and 25 children of ages 3 to 5 years who were believed to be “normal” in this respect. Prior to the study, all food was removed from the children’s homes. The food for the experiment was delivered by a van serving as a mobile testing laboratory. Each week, all food was removed, with the new supply introduced.
Flavor was controlled by substituting aspartame or saccharine for sucrose (sugar). Three sham diets were used to help disguise the presence or absence of sugar. All diets were free of additives, food colorings, and preservatives. Each subject received 3 weeks of each sweetener (sugar, saccharine, and aspartame) with the sham diets rotated randomly. Thus, each subject received each combination of sweetener and sham diet for one week.
Cognitive and behavioral tests were administered weekly, including ratings by parents, teachers, examiners, and self-reports from the children tested. The results showed no significant differences among the 3 diets for any of the 39 behavioral and cognitive measures.
Four major limitations of the study should have deterred the authors from the sweeping, broad conclusion they adopted:
1. The amount of sugar in the test diets was not large, and actually was in the high-normal range based on available data for sugar intake in the U.S. population.
2. The sugar was spread evenly over the day. No binges occurred, since there was no candy or other foods that would appeal to someone with a “sweet tooth.”
3. The criteria for selection of subjects seem quite weak … and were based only on parents’ subjective belief of a sugar problem. There was no careful screening to ascertain striking or mild symptoms. There was no pretesting of children to ensure that appropriate candidates were in the study.
4. The diets in all cases were nutritionally terrific, including absence of food dyes, preservatives, and other additives. This is not at all representative of the typical American diet.
This was a carefully conducted study that provides interesting and valid information. However, it does not support the conclusions of the authors. The study shows that children with very healthy and nutritious diets are not affected by the presence or absence of high-normal amounts of sugar given gradually over the day. One cannot infer from this that children with poor diets are impervious to sugar, nor that children who binge on sugar are unaffected.