London: Catching viruses such as flu when you`re younger could protect you from developing allergies later in life, says a new study.
Kids today are far too `clean` for their own well being as the immune system can over-react if it doesn`t have enough viruses to fight, it points.
The study bolsters evidence that an increasing number of children in developed countries are suffering from allergies because they are not exposed enough to bacteria and viruses, according to the Journal of Clinical Investigation.
In the latest research, scientists from Harvard Medical School found that baby mice infected with the influenza A virus grew into adults that were protected against induced symptoms of the condition, the Daily Mail reports.
However, adult animals catching flu remained susceptible to asthma. Scientists traced the effect to a sub-group of immune system cells called natural killer T-cells (NKT cells).
Some NKT cells appear to keep the immune system under control and prevent the extreme reactions that lead to allergies such as asthma. In the baby mice with flu, but not the adults, the numbers of these cells were found to increase.
The research also showed that NKT cell protection against asthma could be induced by exposing baby suckling mice to a molecule from the stomach bug Helicobacter pylori.
The findings provide strong evidence in support of the `hygiene hypothesis` - the theory that we are too clean for our own good.
The scientists, led by Dale Umetsu, wrote: "Our results suggest that infection with certain micro-organisms can prevent the subsequent development of asthma and allergy by expanding."