The emotional moments started piling up. Nearly two weeks later, Jeff, 46, bought his son a new top. Nicholas turned to his dad and-with a child's tact- said, "No, I don't like it." Vicky still shakes her head at the memory: "Five words. A sentence. Jeff and I couldn't believe it."

What Vicky and Jeff do believe is that Nicholas's astonishing turnaround is a result of what they had been feeding-or more importantly, not feeding-their son. After removing gluten and dairy from his diet, they noticed an immediate improvement in Nicholas's cognitive, physical and emotional skills. Autism-spectrum disorders (including Asperger's syndrome) affects about one Australian child in 160 and while there is as yet no proof that diet cures the brain disorder, Vicky says that her son, 3, "is now a vibrant, alert, interactive little boy."

Yet only a year ago, Nicholas's behaviour was reducing his mother to tears. "He wouldn't really look at us and when we called his name he didn't respond," says Vicky. "He seemed to be in his own world." Aged 2, Nicholas started going to a Montessori kindergarten and when Vicky went to pick him up one day, "I looked through the window," says the professional child photographer, "he was sitting in a group going, 'Aaah, aaah, aaah' and wouldn't stop. I knew something wasn't right."

As did two of his teachers, who told Vicky and Jeff that Nicholas displayed "characteristics" of autism. "He'd say some words over and over again, and was fascinated with power cords and light switches," says Vicky. And while Jeff, a firefighter, initially refused to believe anything was wrong with his son, one episode proved pivotal. "I was trying to discipline Nicholas for throwing the remote control," says Vicky. "He just wasn't getting it. I picked him up and yelled in his face, `No!' I was crying and distraught. Any normal child would get scared if their parent yelled like that. Nicholas just giggled. We went from denial to fear."

Since their paediatrician said it was too early to diagnose, the couple sought alternative advice. They visited a naturopath, who said that the boy may have leaky gut, a syndrome where toxins from the stomach enter the bloodstream. The naturopath suggested the removal of gluten and dairy from Nicholas's diet. They didn't take this diagnosis seriously until they met a parent of an autistic child who had had success with the same treatment. So on May 27, 2007, the family bought rice milk and changed their pasta and bread to wheat- free. The next day came the "Get" incident. Says Vicky: "Our lives changed in 24 hours."

So were gluten and dairy causing Nicholas's behaviour? Paediatric dietician Sally Girvan says in cases such as this, proteins such as gluten - found in wheat, rye, barley and oats - and casein, the protein in all mammalian milk, are not properly digested. They form small groups of protein called peptides, which, in some cases, "are absorbed into the bloodstream," says Girvan, a member of the professional panel of Autism Victoria. "[They] stimulate the opioid receptors in the brain and produce that disconnected, spaced-out feeling people get when they are on opioids like morphine." Still, there is "no conclusive scientific evidence" that such a diet cures children, says Girvan, "but there is a small percentage of children it does help for whatever reason."

Like Bondi, Sydney, boy Ethan Heng. Kim and Chong Heng's child was diagnosed with autism at age 2. By age 4, Ethan spoke only about 10 words and would often stim - a repetitive behaviour such as flapping his arms or spinning in a circle. Like the Leons, the Hengs learnt through other parents that cutting gluten and dairy could change a child's behaviour.

After changes to his diet, Ethan's stimming behaviour stopped and within a week, he could recite the alphabet. "Oh my God, he changed!" says Kim, 35. "He's a totally different boy. I still regard him as autistic, but he is 200 times better."

And there are more such cases in Australia. Jan Brenton, moderator of the Biomedical Autism Group, has heard from 600 families whose children are progressing through diet change: "It's so simple it seems too easy and is often brushed aside." The results continue to overwhelm Vicky. "Every day we see things that are an improvement," she says of Nicholas, who is now treated by a doctor specialising in autism. "I love it when he looks at something, looks at me and then smiles. We never had that connection before."

Reported by Sarah Marinos - WHO Magazine - Breakthrough - 2008