The number of young people affected by wheat intolerance may have been underestimated, research suggests.
Gluten is found in wheat
A study by Bristol University has found as many as one in 100 children may have coeliac disease.
Currently, fewer than one in 2,500 is treated for the disease, which is actually an intolerance to a substance called gluten found in cereal flour.
The research, based on 5,470 seven-year-olds, is published in the British Medical Journal.
The researchers found that although a large number of young people appear to have the disorder, many do not show obvious symptoms.
They believe that coeliac disease is often triggered in childhood, but symptoms might not appear until years later.
The condition is caused by an oversensitivity to gluten of the lining of the small intestine.
This leads to inflammation of the gut, and an inability to absorb adequate nutrition from food.
Symptoms can include tiredness, anaemia, weight loss and diarrhoea.
Researcher Dr Polly Bingley analysed blood samples collected from the children, looking for antibodies which are markers of the disease.
A total of 54 children tested positive for the antibodies - but only four were on a gluten-free diet.
Girls were also more than twice as likely to have the antibodies as boys.
The children had only mild, if any, gastrointestinal symptoms.
However, Dr Bingley also found that on average the children with the antibodies were 2.7cm (1in) shorter and 1kg (2.2lb) lighter than those who did not.
She said: "This equates to about nine months' growth and weight gain in an average child around this age."
It is not known whether this stunted growth is directly linked to coeliac disease.
However, there is some evidence to suggest that babies born with the disorder tend to be smaller, suggesting problems may start in the womb.
Around 1% of the UK's adult population is known to have coeliac disease, but it is thought this is also underestimated.
Dr Bentley said: "We have found that the frequency of coeliac disease at age seven is the same as that we find in adults in this country, suggesting that the condition starts in childhood, even in individuals in whom it is diagnosed late in life.
"They don't suddenly develop coeliac disease - they've probably had it for years before it is eventually detected."
The researchers hope the study will lead to new studies into possible causes of the disease, looking at infant foods and influences on the baby in the womb.
It could also pave the way for new treatments or prevention of the disease.