Tom Chivers:

It started simply enough – with suggestions that her child should follow an unremarkable-sounding special diet. “They did these tests: a stool test and a urine test,” Layla (not her real name) tells BuzzFeed News. “I can’t remember where they were from – not the NHS, obviously, but some lab. The results had all these red markers.” The tests, from an alternative medicine practitioner who was recommended by and paid for by a major charity, apparently showed that Layla’s son, an autistic boy who was 3 at the time, had various issues with his gut and his metabolism. “I was shocked,” says Layla. “I didn’t realise – my son had all these deficiencies, these toxins in his system.”

The tests recommended a gluten-, casein-, and dairy-free diet. “It didn’t seem like a really big deal,” says Layla. “I thought, gluten, it’s bread and pasta – it’s not a massive thing.” The practitioner told her to monitor her son’s sleep and behaviour, and to expect improvements in the symptoms of his autism if they followed the diet.