Significantly, the figures appear to indicate that coeliac disease is triggered in childhood, although the symptoms might not appear until years later.

The results, from the Children of the 90s project, also known as the Avon Longitudinal Study of Parents and Children, based at the University of Bristol, will help guide future research into possible causes of coeliac disease, looking at infant foods and influences on the baby in the womb, said researchers.

Dr Polly Bingley from the University of Bristol analysed blood samples collected from 5,470 seven-year-olds, looking for antibodies that are markers for the disease. While 54 of the children tested positive, only four were on a gluten-free diet.

The findings, published in tomorrow's issue of the British Medical Journal (328:322-323), revealed that 1 per cent of children had antibodies to tissue transglutaminase and endomysial antibodies, indicating a very high probability of undetected or subclinical coeliac disease.

Girls were more than twice as likely as boys to have these antibodies and on average, the children who had these antibodies were 2.7 cm shorter and 1kg lighter than those who did not.

"The children had only mild, if any, gastrointestinal symptoms. A striking observation was that they were shorter and lighter than antibody negative children matched for date and place of birth. This equates to about 9 months' growth and weight gain in an average child around this age," said Dr Bingley.

It is already known that 1 per cent of the UK's adult population have coeliac disease. The illness is often represented as an iceberg since only a minority of affected individuals are diagnosed.

People with the condition suffer inflammation of the gastrointestinal tract, caused by a protein present in wheat and some other cereals which damages the lining of the small intestine and reduces the ability of the gut to absorb adequate nutrients from food.

The symptoms vary widely; many people show no outward sign of the condition, some complain of tiredness and anaemia, while others experience weight loss and obvious gastrointestinal symptoms such as diarrhoea. Coeliac UK, who funded the research, say the intestine generally returns to normal with a strict gluten-free diet.

“We have found that the frequency of coeliac disease at age 7 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,” said Dr Bingley.