The Prince of Wales will urge doctors to start using unconventional techniques such as chiropractic, acupuncture and herbal medicines to treat serious illnesses, in a speech to the World Health Organisation next week.
Prince Charles will claim that such major chronic illnesses as diabetes and heart disease, which affect tens of millions worldwide, could be successfully treated using complementary medicines and a "whole body" approach to healthcare.
His comments, which will invite fresh complaints from his critics, are to be made in a keynote address to the annual WHO Assembly in Geneva on 23 May, where the Prince will set out his case for "integrated healthcare" to a global audience for the first time.
The Prince is expected to argue that doctors should put less reliance on conventional drug-based treatments and take a more "holistic" view by putting greater emphasis on preventive healthcare, diet and healthy lifestyles.
This would help tackle endemic diseases such as strokes, heart disease and diabetes which kill 35 million people annually, and which are the cause of 80 per cent of GP referrals in the UK each year, he will say.
The Prince also believes there is proven evidence that some mental illness can be treated without anti-depressants, for example, using the herb St John's wort for post-natal depression.
Doctors and governments should be focusing on diet, environmental pollution and reducing the use of harmful chemicals in homes and farming, he will say.
In a speech last year when he was made an honorary fellow of the Royal Society of Medicine, Prince Charles said that modern Western lifestyles played a major role in the rise of allergic diseases such as asthma, various cancers and in obesity.
"The human body has too often been mechanistically reduced to individual parts and treated with limited reference to the whole person," he said then.
"We need to harness the best of modern science and technology, but not at the expense of losing the best of what complementary approaches have to offer. That is integrated health - it really is that simple."
Officials at Clarence House say the Prince is gratified that the WHO has invited him to promote the case for complementary therapies and "integrated health" - a subject which he has championed for several decades, setting up the government-funded Foundation for Integrated Health in London.
He has frequently been attacked by the medical establishment for pursuing "crank" theories on health after he first advocated non-conventional medicine to the British Medical Association in 1982. Critics accused him then of a "flight from science".
His address to the World Health Assembly is a "sign of how far the debate has moved on", said one official. Integrated health was now the "subject of mainstream discussion".
But Prince Charles will avoid mentioning one of his most contentious personal interests - homeopathy, the widely disputed theory that minuscule doses of medicine can cure illness.
Prominent cancer specialists were also aghast when the Prince advocated the Gerson diet method of treating cancers. Michael Baum, emeritus professor of surgery at University College London, bluntly said Prince Charles had "got it wrong" and urged him to "exercise your power with extreme caution" when it came to health matters.
THE PRINCE'S WAY
ACUPUNCTURE The ancient Chinese science of inserting needles in key points on the body can help osteoarthritis, menopause symptoms and nausea in childbirth.
HERBAL REMEDIES Some have proven value - St John's wort for depression, and Chinese medicines for eczema and hay fever.
CHIROPRACTIC Mostly manipulating the spine, this can treat muscle and joint pain, migraine, asthma, menstrual pain and sports injuries.
DIET Prince Charles is a keen fan of organic, pesticide-free foods and supplements such as Omega 3 and fish oils, saying they improve health and cut the risk of illness.