Feeling angry? Let it all out, punch a pillow, blow off steam, but don't keep it in, right? As Claudia Hammond discovers the evidence is far more complicated.

How often have you heard the advice to not to keep any anger in for the sake your health? There's a common notion that suppressing your anger must be bad for your body, or at least give you a stomach ulcer. From time to time you read reports showing that it could be bad for your heart. But when you look across the evidence that has built up over the years, what does it reveal about managing anger?

In terms of ulcers, whether you storm around the room raging or simmer in silence, you can still get them. While stress was thought to be a major contributing factor, there's no clear evidence that it depends on whether or not you express your anger, as it's now known that most ulcers are caused either by the bacteria Heliobacter pylori or by prolonged use of non-steroidal anti-inflammatory drugs.

When it comes to the heart, the evidence is more mixed. In a study carried out at the University of North Carolina in 2000, 13,000 patients were given questionnaires in which they rated their own tendency to get angry, and were followed up a few years later. Although their blood pressure was apparently normal, those who had said they frequently lose their temper were three times more likely to have had heart attacks in the intervening years than the others, even when factors like smoking, diabetes and weight had been taken into account. Likewise, Mark McDermott from the University of East London found that people who expressed their anger suffered more from heart disease than those who held back from shouting.

Some reports suggest keeping anger in could be bad for your heart, but this isn't the whole story (Thinkstock)

Express yourself

This all seems plausible, especially as there are known physiological mechanisms through which expressing anger could be problematic. When you lose your temper your face reddens, your jaw clenches and your heart starts racing in preparation for fight or flight. The body gets ready by taking fat from smooth muscle in case you need extra energy. If those fatty acids aren't used they have to go somewhere and can end up clinging to the artery walls, and these deposits can contribute to heart disease. 

Each time your blood pressure shoots up you can be left with scar tissue left by the tiny injuries inflicted on the coronary artery walls, which in turn can also contribute to heart disease. The occasional scar is no problem, but theoretically if this is repeated day after day the harm could start to build up. A healthy heart can deal with this, but if someone already has coronary heart disease then on rare occasions the sudden rise in blood pressure can cause fatty deposits inside the wall of the arteries to break off and block the artery. If this means blood can't reach the heart, the result is a heart attack; if it can't reach the brain then you have a stroke.  

But other studies have shown no link between anger and heart disease, or that people with high blood pressure seem to be more likely to suppress their anger. The problem is that studies measure both heart disease and the expression of anger in so many different ways that they're hard to compare.

Blood pressure-related injuries to coronary artery walls can contribute to heart disease (Thinkstock)

In an attempt to get to the bottom of the mystery Giora Keinan from Israel looked not only at how frequently people get angry, but at the intensity of that anger. She found that in terms of health, the best thing to do is to get very angry, making your case "clearly and firmly", but to do so only rarely. She suggests that the people who do this are likely to be the same people who are good at finding other ways of dealing with difficult situations. This reduces the amount of stress they experience, and in turn improves immune function, leading to better health.

Another possibility is that it all depends on how you express your anger. A study in Canada took 785 randomly selected adults and followed them up for a decade. They found that men who expressed their anger constructively, using it to try to get something done, were less likely to develop heart disease. In women it made no difference. But in both men and women expressing anger in a way that sought to blame others, and to justify their own actions was associated with more heart disease.

Ready to rumble

Even if studies are inconclusive as to whether getting angry is always good for us physically, surely the mere act of letting it all out will provide some relief, won't it? Maybe not.

This will help get rid of anger, won't it? (Thinkstock)

Some therapists give people pillows to punch, but this isn't always as cathartic as it sounds. In fact it can increase your feelings of anger. In one study people received insulting criticism about an essay they'd written, including feedback such as "this is the worst essay I've ever read". Half the people were then given the chance to vent their anger by hitting a punch bag. They said they enjoyed it, but when they were then given the chance to subject a competitor to loud noises in another part of the test, they punished the people with louder noises than the other group did. It seems that far from calming them down, the bag-punching had in fact made them more aggressive.

The same researchers also made people believe they'd been given a drug which would freeze their mood for an hour (although this seems implausible, none of the participants expressed suspicion). After they were made to feel angry, far fewer bothered to hit the punch bag, suggesting that we do these things because of a belief that it will make us feel better, even though it might not.

So what does this all tell us? Well, it suggests that holding your anger in doesn't do you much harm, that the occasional outburst is probably OK and that it's not so much whether you get angry that matters, but how you do it and how often.

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