A new study, published in the American Journal of Psychiatry, explores a possible mechanism behind the link between artificial food additives and ADHD symptoms.
“This study sheds light on how synthetic food dyes affect behaviour,” said Jane Hersey, director of the Feingold Association which helps special needs children. “It may also help solve the mystery of why these additives have a very powerful effect on some children and a milder effect on other kids.”
The answer may lie in the children’s genetic makeup, according to the new study’s authors. They found that children with certain slight variations in the HNMT gene, which helps break down histamine in the body, have stronger behavioural reactions to food dyes than those without the variations.
While histamine release is known to be involved in the sneezing, coughing and runny noses associated with the common cold, the authors noted that this compound also affects transmission of nerve signals in the brain. They explained that children with these gene variations had trouble degrading the histamine released by their bodies in response to the food additives and that the neurological effects caused by the excess histamine resulted in increased symptoms of attention deficit hyperactivity disorder (ADHD).
The researchers pointed out that in addition to environmental toxins like artificial food additives, many foods and infections also increase histamine release. “This would explain the frequent claim that food allergy/intolerance is a cause of ADHD symptoms, and the effects of infections in aggravating aberrant behaviour,” they wrote.
The authors also called for further research on the interaction of genes affecting neurological systems and environmental factors like diet, in order to better understand genetic influences on ADHD symptoms.
This study was based on a highly acclaimed 2007 trial published in the British medical journal Lancet, which concluded that synthetic food dyes increase hyperactive behaviour in all children, not just those diagnosed with ADHD.
The American Journal of Psychiatry study also cited a 2004 meta-analysis of 23 controlled trials (including 15 with exclusively hyperactive children), which showed that children’s behaviour is affected by artificial food dyes and called for an “ambitious vigil against avoidable harmful exposures.”
This research led representatives from the Feingold Association and the Center for Science in the Public Interest to meet with Food and Drug Administration officials on March 1 in Washington, D.C., where they called for removal of synthetic dyes from the food supply or, at a minimum, warning labels.
Hersey, whose eldest daughter was helped by the low-additive Feingold Diet, hopes that these efforts will result in the eventual disappearance of these chemicals.
“The purpose of food dyes is strictly cosmetic — to make the foods more marketable,” she said. “Since they have no nutritional value and are actually harmful, they have no place in the foods we are feeding our kids.”
Howard AL, Robinson M, Smith GJ et al. ADHD is associated with a "Western" Dietary Pattern in Adolescents. Journal of Attention Disorders, 2010; (DOI: 10.1177/1087054710365990)
Stevenson J, Sonuga-Barke E, McCann D, et al. The Role of Histamine Degradation Gene Polymorphisms in Moderating the Effects of Food Additives on Children’s ADHD Symptoms. American Journal of Psychiatry June 15 2010 (doi: 10.1176/appi.ajp.2010.09101529)
McCann D, Barrett A, Cooper A, et al. Food additives and hyperactive behaviour in 3-year-old and 8/9-year-old children in the community: a randomised, double-blinded, placebo-controlled trial. Lancet Nov 2007;370(9598):1560-7.
Schab DW, Trinh NT. Do artificial food colors promote hyperactivity in children with hyperactive syndromes? A meta-analysis of double-blind placebo-controlled trials. Journal of Developmental & Behavioral Pediatrics Dec 2004;25(6):423-434.
"Modernising the rules on food additives and labelling of azo dyes," European Parliament, July 8, 2008.
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