ADD / ADHD, ADD / ADHD Diagnosis, ADD / ADHD Treatment

Food Colorings and Hyperactivity

Diet and food additives have been suspected as a cause of ADHD since the 1970s and the Dr Feingold diet. After its period in the sun, the idea that certain types of food or chemicals in the food causing ADHD was discarded by mainstream science because the research failed to show any consistent results. This did not stop many thousands of parents changing their children’s diets, often with remarkable success stories.

Now, the UK Food Standard Agency has released the results of complex and top-rate research it has been doing into food colorings. Rather than looking for an individual cause, it looked at mixtures of chemicals commonly found in drinks aimed at children. They tested two mixtures on 260 children split into two age groups, three years old and eight years old. The children including a range of ADHD symptoms from none to extreme so that the study could assess whether the chemicals increase existing symptoms or cause ADHD in those with no symptoms. The study lasted six weeks and during which the children were assessed by the parents, teachers and most importantly, a trained independent observer. The trial was a double blind study so that none of the children, parents, teachers or observers knew whether the child was receiving mixture A, mixture B or a placebo. A second stage of the study used a subset of the children and observed them under tightly controlled laboratory conditions.

The results were complex. Three year olds responded with a significantly increased level of hyperactivity to mixture A whereas the eight year old responded more to mixture B. Also not all children responded the same way and the levels of response where not connected to the child’s existing levels of hyperactive behaviour.

Part of the research was to see if genetic make-up played a role in how children reacted to the drinks. They found that children with genes relating to impair histamine clearance (histamine N-methyltransferase, HNMT Thr105le and/or HNMT T939C). Children with these genes did show a significantly greater reaction to the both mixtures.

One area the research did not clarify is how long the effects last. At various points during the study, children were on a placebo to give the body a chance to remove any residual chemicals. This seemed to be enough but as the children had only been taking the chemical mixtures for a week or two, its is not clear how long they would stay in the body if the child regularly consumed them over several months.

The study has not produced a clear culprit for ADHD and the study authors admit that the results they have seen could be down to chance. However this study and previous work does indicate diet can have an effect, and sometimes a very strong effect, on some children. Should parents avoid these chemicals? I think my advice from the last time Myomancy looked at diet and ADHD still holds true:

The best advice currently available is for children to eat a balanced diet with lots of fruit and vegetables. This will certainly help prevent weight problems and improve the child’s overall physical and neurological development. If the diet helps treat ADD / ADHD then that’s a bonus.

FSA’s Press Release
Comments on the study from the FSA’s Chief Scientist
Chronic and acute effects of artificial colourings and preservatives on children’s behaviour: Study design and results.
Detailed review by the FSA’s Committe on Toxicity of Chemicals in Food, Consumer Products and the Enviroment. [ PDF ].

The chemicals and colorings used in the study

Mix A replicated the food colours and preservatives used in a previous study and consisted of:

* Sunset yellow (E110)
* Tartrazine (E102)
* Carmoisine (E122)
* Ponceau 4R (E124)
* Sodium benzoate (E211)

Mix B consisted of:

* Sunset yellow (E110)
* Quinoline yellow (E104)
* Carmoisine (E122)
* Allura red (E129)
* Sodium benzoate (E211)

Sodium benzoate was included in both mixes, but the effects observed were not consistent. The Agency therefore considers that, if real, the observed increases in hyperactive behaviour were more likely to be linked to one or more of the specific colours tested.