Avoiding some foods could help children with ADHD

BMJ Group News

What do we know already?

Attention deficit hyperactivity disorder (ADHD) affects about 5 in every 100 children. The main features are difficulty paying attention, over-activity and impulsiveness. While all children behave in this way at times, ADHD means the child usually behaves in this way, in all situations, and this is badly affecting his or her life.

Treatment is usually through medication, as well as therapy and often education for parents. But there’s been much interest in whether certain foods trigger ADHD behaviour, and whether cutting out these foods could help treat the condition. Previous studies have been too small, or not given clear enough results, to answer this question.

Researchers have now done a two-stage trial, to find out first whether a restricted diet might be helpful, and second whether allergy testing or reintroducing certain foods can help identify allowed foods and problem foods.

What does the new study say?

The children who had a restricted diet in the first part of the study showed an overall improvement in symptoms of ADHD.

Of the 41 children following a restricted diet, 32 responded well (meaning that their symptoms were rated at least 40 percent lower than at the start of the study).

Children then had blood tests to see if their immune systems reacted strongly to certain foods, which could indicate an allergy. But re-introducing foods based on the results of the blood tests didn’t work. Children’s behaviour got worse when certain foods were re-introduced, whether their blood tests showed an allergic reaction or not.

The restricted diet was quite strict. It’s called the ‘few foods’ diet and is limited to foods unlikely to cause allergic reactions. These include rice, turkey, lamb, a range of vegetables (lettuce, carrots, cauliflower, cabbage and beetroot), pears and water. Other foods, including potatoes, corn, wheat and other fruit, were added in a controlled way, with a dietician advising in each child’s case, to find a suitable diet for that child.

How reliable are the findings?

This was a randomised controlled trial, which is the best type of study to tell whether a treatment works. However, it wasn’t possible to disguise whether children were eating the restricted or normal diet, so it’s possible that some of the change in behaviour was down to parents expecting their children to behave better because of the diet.

The study included 100 children, which should be big enough to give fairly reliable results.

Where does the study come from?

The research was done in the Netherlands, and published in the Lancet medical journal, owned by Elsevier. It was funded by several child health foundations.

What does this mean for me?

If you have a child who has ADHD, you may wish to try an elimination diet, to see if it helps. This study suggests it works for about 78 in 100 children.

However, it’s important to make sure that your child gets all the nutrients he or she needs, as a growing child. You should speak to a qualified dietician about this. You could ask your doctor for a referral to an NHS dietician.

There’s an important difference between a dietician and a nutritionist. Anyone can call themselves a nutritionist without having any qualifications, while a dietician has to do a standard training course and qualification.