An Oxford scientist has developed a nasal spray made from powdered shrimp shells, to prevent hay fever and allergic asthma.

Peter Strong, a researcher in Oxford University's biochemistry department, has patented his invention, called Allermatic, which uses micro-particles of chitin, extracted from shrimp shells.

Chitin is related to the weight-loss supplement chitosan, and to glucosamine, used by athletes and arthritis sufferers to strengthen their joints.

Dr Strong said: "In Italy, the spray is now in preliminary clinical trials for treating allergy in patients from age 7 to 30."

Because chitin is a natural product extracted from food, it does not have the safety worries associated with other hay fever treatments.

Dr Strong was one of seven runners-up in the Oxford University Business Plan Competition at Venturefest 2003 and narrowly missed winning the top prize of £10,000, which would have enabled him to set up a company to commercialise the spray.

He said: "It would be so safe that you could use it as a preventative, just as you might give your children orange juice or vitamin C."

Dr Strong said the spray worked because the immune cells of the nasal membranes recognise chitin.

"The immune cells naturally reponds to chitin and this reverses the imbalance that allergy causes to the immune system."

He added: "It is so simple and so safe."

He said traditional treatments were based on steroids, and were dangerous for children to take long term.

Chitin is a natural immune enhancer. Most new immune enhancing anti-allergy treatments are derived from bacteria and not suitable for long-term use.

"The hope is that we can produce a really safe treatment that can be used on a long-term basis to prevent the development of childhood asthma, which is a growing problem in the UK."

In a report last week, the Royal College of Physicians said the NHS could not cope with the rising incidence and increasing severity of allergy in the UK.

One in three people is expected to develop allergy at some time in their lives. Previously rare and severe allergies are also on the increase and more children are affected, particularly by peanut allergy, according to the report.

Kieron Leech, of the Said Business School, who was part of the Allermatic team in the business plan competiton, said a venture capital company had expressed interest in funding the idea.