Adapted from Pure Facts Newsletter, May 1998.

Newer Studies Yield Support for
Diet/ADD Connection

"The often-quoted position that 'the relationship between diet and hyperactivity has not been proven' was based on research in the 1970's. It is now timely to consider the useful studies of the 1980's and 1990's that clearly show a relationship."

Joan Breakey is a dietitian/nutritionist in Queensland, Australia who has studied and written extensively about the effects of foods and food additives on children. In 1997, the Journal of Paediatric Child Health (1997, vol.33, 190-194) published her paper, Review Article, The role of diet and behaviour in childhood.

The paper follows the history of the studies, from the early, somewhat crude versions, to improved methods which were introduced, starting in the mid 1980s.

The earlier studies looked for changes in hyperactivity and learning tasks, but in later studies reports from parents showed that other symptoms changed. Sleep disturbances were often mentioned by parents.

"Symptoms which may change include those seen in attention deficit disorder (ADD) and attention deficit hyperactivity disorder (ADHD), sleep problems and physical symptoms with later research emphasizing particularly changes in mood....An important unexpected finding is the number of researchers who emphasize that the symptom most affected by diet is mood, especially irritability."

Newer studies were designed to avoid some of the serious shortcomings of the earlier trials, including the potential for `placebo effect.' and the size of the population studied. "The numbers [of children] studied in the recent studies collectively are significant. Diet establishment time was considered and the period on diet was longer, as were the challenge phases and wash-out periods. With these changes in study design the problems of order effect in earlier studies were resolved."

"The most important finding was that in almost all studies there was a statistically significant change in behaviour with dietary intervention. A degree of change was noted with partial and full responses occurring rather than the all-or-nothing earlier expectation." Later study designs also took into account food allergies and environmental sensitivities. A family history of allergy and migraines was found to increase the chance of a child's success using dietary intervention. Researchers looking only at allergy foods or only at additives could miss some children who would otherwise respond.

"Non-food items that have been implicated are perfumes, fumes, inhalants..." Breakey addresses the question of why some researchers find that the removal of allergy foods helps, while others see improvement from eliminating some additives or natural salicylates. She suggests that any of these could result in a reduction of the `total body load.'

"By the 1980s recognition of the complexity of the issues was reflected in methods that investigated more suspect substances and monitored a wider range of areas of change."

She writes that the improved symptoms noted by parents were sometimes different from those reported by teachers. "This adds weight to the concept that parents and teachers monitor different symptoms and that this difference can add rather than detract from results..." The many successes Dr. Feingold described were based on the reports from parents, not from teachers. Critics frequently overlook this, especially when they cite the very early Harley study at the University of Wisconsin, where the all ten mothers of preschoolers found the diet to be successful.

"In the past the procedure seemed simple: investigate artificial colours in hyperactivity, chocolate in migraine, diary foods in asthma and so on. It has now become clear that such specificity does not apply and any investigation should include the broad range of presenting problems and suspect substances."

Brain activity of children with ADHD responds to certain foods.

Another study, carried out in Australia and published last year, supports the connection between diet and its effect on behavior and learning.

"In 15 children suffering from food induced attention deficit hyperkinetic syndrome, topographic EEG mapping of brain electrical activity was carried out following avoidance and ingestion of previously identified provoking foods....During consumption of provoking foods there was a significant increase in betal activity in the frontotemporal areas of the brain.

"These data support the hypothesis that in a subgroup of children with attention deficit hyperactivity disorder certain foods may not only influence clinical symptoms but may also alter brain electrical activity."

Topographic mapping of brain electrical activity in children with food-induced attention deficit hyperkinetic disorder. Uhlig T, Merkenschlager A, Brandmaier R, Egger J. Institute for Child Health Research, Clinical Sciences Division, West Perth, Australia. Eur J Pediatr 1997 Jul;156(7):557-561.

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