A boy of 12 suffers from so many allergies that he is able to eat only five foods.
Tyler Savage is violently ill every time he is given dishes containing dairy products or wheat, gluten, eggs, lactose and soya.
The sole foods he is allowed are chicken, carrots, grapes, potatoes and apples.
To help him survive, minerals and vitamins are pumped directly into his stomach through a tube.
Tyler started to fall ill at the age of six when even a morsel of food would leave him writhing in agony from sickness and diarrhoea.
His mother, Lynne Savage, 43, said: "We asked for help but kept being told that he was suffering from a stomach infection. As a result his weight dropped drastically.
"He ran out of energy really quickly and couldn't do the things other children were doing. He just seemed to be getting worse and worse.
"It's been a real struggle. We didn't know what to do."
Tyler - from Earls Colne in Essex - was seen by a paediatrician at Chelmsford's St John's Hospital and had his appendix removed in December 2005.
Although the operation was a success it failed to solve the problem and he was referred to Colchester General Hospital for further tests and treatment.
That shed no light on the mystery illness and in April last year Tyler was sent to Great Ormond Street Hospital in London for checks on his stomach and bowels.
The tests led to a diagnosis of eosinophilic enteropathy, a rare and condition in which the intestines produce too many white blood cells.
These act as a miniature immune system and attack food passing through the gut to the stomach.
The condition saw Tyler's weight drop to barely three stone.
"He was becoming malnourished," said Mrs Savage, a married mother-of-three and housewife.
At first, Tyler was fitted with a nose tube to help get food direct to his stomach, bypassing the rogue blood cells in his gut.
Then, this May, he had a tube inserted into his stomach allowing him to be fed for up to ten hours through the night.
"Even though this will continue for the foreseeable future, it is a godsend," said Mrs Savage.
"Last year he was only at school for about ten days, but in the first two weeks of this new term he's only missed one day.
"We've got a long way to go but at least we're now getting some answers."
In the day, Tyler, whose father, David, 60, is an engineer, can eat the five foods he is not allergic to.