While there is general agreement that anger kills, experts are arguing heatedly among themselves about whether it is healthier to express anger openly, or "count to 10". Professor John Grimley Evans, of Oxford University's clinical gerontology department, believes the wilful and cantankerous live longer than "more compliant, sweet old folk who make good patients". His theory is backed up by doctors who work with cancer sufferers, the less placid showing better recovery rates than those who passively accept their fate.
But learning to deal healthily with anger isn't quite that simple. Dr David Lewis, a leading stress consultant, proposes a more controlled approach. He helps angry executives "change their perception of events", by regarding setbacks as challenges and traffic jams as a chance to learn a foreign language or practise a speech. "If you miss your train," he advises, "don't vent your anger on the taxi driver or stationmaster. Instead, take the opportunity to review your time management skills.
"Plan ahead for such eventualities," he adds, "so you don't have to make a decision when you're angry. Decisions made in anger are seldom good ones."
Dr Lewis's advice on "containing" anger is also based on sound research. Dr Redford Williams of the Duke University Medical Centre in North Carolina, has found clear links between anger and heart disease. Perhaps unsurprisingly, "driven" types in their 20s who are prone to angry outbursts are the most likely to have coronary heart disease in their 40s. He believes anger suppresses the immune system, as well as raising the heartbeat and blood pressure and constricting blood flow to internal organs (classic aspects of the "fight or flight" response of which anger is a vital part).
Other stress experts, such as Dr Malcolm Carruthers, argue that controlling anger isn't necessarily the solution. Expressing it through screaming, ranting and cursing is necessary on occasions. Visitors to his Harley Street surgery might be offended by the blue language that emerges as part of his "intentional anger release" exercises.
How can there be two such opposite suggestions for dealing with anger healthily? Carruthers believes this is because the emotion comes in two guises. "There is a difference," he says, "between constructive and destructive anger. The racing driver who needs to rev up his aggression to achieve peak performance is very different from the commuter stuck impotently fuming in a traffic jam."
Anger releases noradrenaline (the "kick-drive" hormone), not adrenaline (the "fear-anxiety" hormone). "Noradrenaline," says Dr Carruthers, "can give a distinctive buzz. Some people get high on being angry, like religious zealots on righteous indignation, because noradrenaline tickles the pleasure centres of the brain."
The hormone also mobilises the "fatty fuels of fury" - free fatty acids from the body's fat deposits - and pushes them into the bloodstream to provide the strength to fight or run away. "That's what anger used to be about in primitive times. Now we just get all steamed up and don't do anything."
With Dr Peter Taggart, a cardiologist at London's Middlesex Hospital, Dr Carruthers studied the blood plasma of racing drivers. They discovered that, under the stress of competition, it became milky with free fatty acids. The drivers could handle this because they were fit, lean and conditioned to run on this "high-octane" hormonal mixture - which the average sedentary commuter isn't.
In less healthy beings, free fatty acids fur up the blood vessels, causing narrowing of the arteries. They make the blood platelets clot together and the heart need more oxygen, until some episode, often anger, causes a heart attack.
Those who channel their anger into action - doing a few laps of Silverstone, or writing scathing letters to newspapers - will be healthier, it seems. The person who complains endlessly about goods and services may be in less danger than the diner who mumbles "Fine, fine" when the waiter asks about an unpalatable meal.
Age also helps people channel their anger more healthily. "Older men and women," Dr David Lewis explains, "have learned to deal with it in a way that suits them. Angry middle-aged people are in the greatest danger, and need to learn to modify their behaviour."
Dr Carruthers agrees. Most of his "autogenic training" clients are recovering heart-attack patients and over-stressed executives, usually in middle age. They are taught to focus on relaxing sensations: heaviness and warmth in the arms and legs; calm, regular heartbeat and breathing; abdominal warmth and cooling of the forehead.
"You can do it in a traffic jam, at the bus stop, anywhere," says Dr Carruthers. "It is mental circuit training. One exercise focuses on the trapezius muscle, in the middle of the back where anger is stored - you 'get the hump' or someone is a 'pain in the neck'. You build up the exercises week by week, to achieve tranquillity without tranquillisers and release your head of steam."
But tranquillity is not the whole story, Dr Carruthers adds. "When you're on your own you can rant and rave and visualise all the things you'd like to do to your boss. Let out your feelings as sounds - as roars - anything that makes you feel better. But this isn't an exercise to try in an open- plan office."
Nick Williams, another stress consultant, organised a "Day of Joy and Humour" in London earlier this year which he claimed would "greatly reduce the possibility of heart attacks". Taking out your anger in a constructive way, with the person you're angry with, is perhaps the most healthy solution, he says. He mentions the title of an American book, Say it Straight or You'll Show it Crooked. "That's what can happen with anger," he adds. "Coming home and screaming at your family because you're furious with your boss isn't a healthy way to behave."
Dr Grace Leung, who runs anger management courses for the Dorset Probation Service, believes self-awareness is the key. "We teach people to recognise what their anger 'norm' is, what pushes them beyond their cut-off point and how to avoid these triggers."
Her clients learn skills like distraction, relaxation and assertion. "Assertion is positive, anger is negative," Dr Leung explains. "You should not be afraid to assert your emotions when someone is puffing a cigarette in your face, but look for methods other than violence."
Of the 30 prisoners she has taught so far, only one has re-offended. Dr Leung believes the same kind of help should be available through GPs. "Ordinary people should learn these methods too. Anger is a normal emotion and we shouldn't be deprived of it - but it's important to make it work for us rather than against us." !