Zoe Connor, of The British Dietetic Association (BDA), says that although diets are a popular treatment for autistic spectrum disorders, and are particularly advocated by alternative nutritional practitioners, there is a lack of consistent and good-quality evidence to back them. Therefore, the BDA recommends no particular diets across the board for treatment.

That said, it admits that there is evidence that supports and refutes the use of gluten-free diets. In effect, this means that it may just work for certain children but not for others.

Because the evidence remains unclear it means that each child has to be assessed within the context of their individual life. Judy Moore, a registered paediatric dietitian, says: “Even if a gluten-free diet may help, it could mean that the quality of the child’s overall diet is compromised, which could in itself have a negative effect.

“It is often a very fine balance between benefits and disadvantages for the child, the parents and, of course, other siblings who can be affected too.”

There is, it seems, some weak but not irrelevant evidence that improvement in ASD behaviour is seen following high-dose supplements of vitamin B6 and magnesium although mega-dosing comes with its own problems, with excess B6 causing nerve damage in some people.

When it comes to big dietary changes, eg, avoiding additives, foods such as chocolate, tomatoes and oranges, or going yeast or casein-free, individual assessment is vital and changes should be made only alongside professional help.