Prince Charles is a strong advocate of complementary medicine

Writing in the Guardian, Prince Charles says 12 million people in Britain suffer from allergies at any one time.

The prince has long been a supporter of complementary therapies such as acupuncture and herbal medicine.

But, he writes, "90% of complementary medicine is currently only available to those who can afford to pay for it".

Allergy is about lifestyle - what we eat and touch, and what we breathe Prince Charles

The prince says the increased comfort and cleanliness of "the Western way of life" is responsible for high numbers of allergies.

"We spend up to 80% of our time indoors, and the sealing of our houses to conserve heat and energy, the increase in soft furnishings... increase the chance of those genetically at risk becoming sensitised to domestic allergens," he says.

He says he wrote the comment piece in the Guardian in repsonse to an article in the same newspaper predicting that half of all Europeans would suffer an allergy by 2015.

"Clearly, something dramatic is happening," he writes.

"The rising trends in allergy seen in developing countries, as they adopt our western habits, point strongly to factors in the way we live."

'Not expensive'

Charles says more complementary medicine should be available to everyone on the NHS.

Complementary therapies emphasise preventative care, and encourage people to take responsibility for their own treatment, he adds.

"It seems extraordinary to me that despite a recent poll indicating that 75% of people want complementary medicine available to all on the NHS, that very few such clinics exist," he writes

Correcting this imbalance "need not mean huge additional expenditure", he adds.

A Department of Health spokeswoman said the NHS did offer a range of complementary medicines and therapies.

"This is part of modernising NHS services, however it is up to doctors to decide what is the best care and treatment for their patients," she said.