Scientists from the University of Bristol, reporting online in thejournal Nature, carried out experiments on genetically modified micethat lacked the part of their immune system that responds to bacteria.They found that 80 per cent of mice raised in a completely germ-freeenvironment and lacking 'friendly' bacteria developed diabetes.
Research last year by other Bristol University researchers found therehad been a five-fold increase in the incidence of Type 1 diabetes inchildren aged under five in the past 20 years.
The latest findings support the 'hygiene hypothesis' - the theory that alack of exposure to bacteria in the developed world may be leading to ahigher risk of developing asthma, allergies and other disorders of theimmune system.
Researcher professor Susan Wong told Nursery World that as theexperiment was carried out in mice, the results could not at the momentrelate directly to humans, but the findings may suggest why the numberof young children with Type 1 diabetes is increasing.
She said, 'Exposure to bacteria conditions our immune system in how wereact. When "friendly" bacteria were introduced in the mice, they gotless diabetes. These bacteria help to train the immune system not toattack itself.'
She added, 'Type 1 Diabetes has appeared to increase in young children.What's important for us to study further is which particular bacteriaare important, when these influences are important in life, and relatethis to human diabetes.
'We'd like to look at patterns of gut bacteria in humans, how thesebacteria condition the immune response and prevent disease.'
According to Diabetes UK, there are 20,000 children under 15 with Type 1diabetes. Dr Ian Frame, the charity's director of research, said, 'Wehave known for some time about the association between early infectionand the development of Type 1 diabetes. As always with experimentsinvolving animal models, the trick for the researchers will be to provetheir hypothesis in humans. The difficulty will be dissecting whatfactors are the triggers.'
He added, 'We wouldn't advise people giving large quantities ofprobiotic foods to children at risk of developing Type 1 diabetes on thebasis of these results.'