Archives of Disease in Childhood, 1990. Jan;65(1):74-7, Heart and Lung Institute, Brompton Hospital, London.
Pollock did a double-blind placebo-controlled challenge study on 19 children who had improved previously on an additive-free diet. He didn’t use any additives but food dyes, but used a total of 125 mg by capsule every morning.
He found that the food dyes did have an adverse effect on the children based on the Conners’ rating that the parents filled out every day, but that the parents couldn’t correctly guess which weeks the children got placebo and which weeks they got “active” (dye-containing) capsules.
NOTE: He reported that “most parents could not detect these changes” which appears odd since they were the same people who had filled out the Conners’ questionnaires that indicated significant change. However, reading the full text carefully, he meant that in order for their once-a-week guesses (separate from the Conners’) to be significant, they had to be right on EVERY week, and most were not. It may be important that only two of the children actually tested in the “hyperactive” range in the Conners’ behavior scale anyhow … which means either the others didn’t even have ADHD to begin with, or the diet worked so well that they were no longer diagnosable and the diet effect overcame the dye-only challenge effect. Yet Pollock was looking for ADHD symptoms as his challenge outcome.
NOTE: Here is another possibility nobody seems to be considering:
Can it be that the opaque capsules used in this and other studies may not dissolve well in their stomach but may simply pass through partly or totally undigested? Certainly they are not absorbed through the tongue or other mouth mucous membranes as they would have been in a real life exposure.