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In this study, which was published in PLOS ONE on 25 January 2017, the effects of three different dietary changes on ADHD are examined. The researchers looked at the influence of fish oil, food colorants and the few foods diet, also known as the restricted elimination diet (RED).
An earlier study, which was published in The Lancet in 2011, showed that the behaviour of children with ADHD strongly improved with the application of RED. However, results from other studies contradicted this. ‘These last few years, various reviews have been published about the influence of food on ADHD’, tells Lidy Pelsser of the ADHD Research Centre. ‘But the conclusions varied greatly. We wanted to know what the exact impact of food is on ADHD.’
Double blind
The research team once again critically analysed the results of various studies. They based their conclusions solely on double blind studies, in which neither the researchers nor the parents and children knew whether the children received the real or the placebo therapy. Additionally, they only looked at studies with children that had actually been diagnosed with ADHD.
The result was striking. The effects of fish oil and a colorant-free diets, currently the two most applied dietary changes, turned out to be very limited. Conversely, the few foods diet had a significant impact, which would mean that it could make a valuable contribution to the treatment of ADHD.
Rice and lamb
The few foods diet assumes that each nutrient can be linked to behavioural problems. The diet is put together for each child on an individual basis, but it comprises at least rice, lamb, turkey, fruits and vegetables, complemented with vitamins and minerals. This is given for five weeks, during which the behaviour of the child is monitored for improvement. If it is observed, the study is continued by adding and removing specific products to see which nutrients the child reacts to, so that these can be avoided in the future.
It is a very strict diet and it is an intensive process that can easily last for 18 months.
Despite the significant effects, Pelsser would advise against applying the diet on a large scale. ‘It is a very strict diet and it is an intensive process that can easily last for 18 months. This requires a lot of motivation on the part of both child and parents. It might be somewhat easier with infants, because those do not have as many extracurricular activities.’
Follow-up study
There is still very little is known about the underlying mechanisms of food in children with ADHD. The remaining questions include: what are the roles of the intestines and the intestinal bacteria, in which way is the immune system involved, what happens in the brain, and are there perhaps specific substances that could be found in blood or urine? To further investigate this, Wageningen researchers are starting a large-scale study this month, in collaboration with the ADHD Research Centre and the Rotterdam paediatrician Rob Pereiradeze.
Pelsser: ‘If we have a better understanding of how it works, the method will hopefully become simpler.’ Children whose ADHD is triggered by food could receive a tailored diet or medicine that focuses on the intestinal bacteria.
Further reading:
Major study on ADHD diet
ADHD symptoms disappear on diet