“The best doctors in the world are Dr Diet, Dr Quiet and Dr Merryman.” – Jonathan Swift
I have a soft spot for medical aphorisms. Some are true: the 19th-century phrase of Welsh origin –“an apple a day keeps the doctor away” – is true of a diet replete with fruit and vegetables. “Feed a cold and starve a fever”, despite its Hippocratic origins, lacks scientific veracity.
What about Voltaire’s “the art of medicine consists of amusing the patient while nature cures the disease?” Indeed is there any evidence that “ laughter is the best medicine”?
Dr William Osler, the doyen of medical teachers, thought it important for doctors to maintain good humour: "Hilarity and good humour, a breezy cheerfulness, a nature 'sloping towards the southern side', as James Russell Lowell has it, help enormously both in the study and the practice of medicine," he wrote.
There is some scientific evidence to show that comedy is good for your heart. In one study, researchers asked 20 healthy people to watch 15 minutes of Kingpin, a 1996 Woody Harrelson comedy. After a 48-hour break, the same volunteers were asked to view the opening battle scene from Saving Private Ryan.
After watching each film segment, researchers carried out a non-invasive ultrasound test to measure the changes in the reactivity of blood vessels. They found that blood flow increased by 22 per cent after watching Kingpin, but decreased 35 per cent after Saving Private Ryan. The average increase in blood flow after exercise is similar to that achieved by watching comedy.
Study author Dr Michael Miller, professor of medicine at the University of Maryland School of Medicine, says watching a film or a sitcom that produces laughter has a positive effect on cardiovascular function and may be as beneficial as going for a run. However, the laughter must be intense – "more of a deep belly laugh", Dr Miller said – and needs to last for about 15 seconds to be effective. After a hearty laugh, it has been estimated our muscles stay relaxed for up to 45 minutes.
Release of endorphins
He believes that laughter exerts its cardiac benefits through the release of endorphins by the brain which in turn leads to the release of nitric oxide by the lining of blood vessels. Nitric oxide is known to dilate blood vessels, reduce inflammation and help prevent cholesterol being deposited in arteries.
And the power of laughter is not confined to heart health. There have been previous reports of skin rashes disappearing when patients with dermatitis watched a Mr Bean video. And a stand-up comedy act apparently helped lower blood glucose levels in patients with diabetes.
In the case of Mr Bean, the researchers demonstrated lower levels of a stress-related chemical in the blood, suggesting that laughter triggered a positive reaction in the immune system of people with dermatitis.
Further evidence of a direct effect on the immune system comes from US research which found that people shown a comedy had higher levels of natural killer (NK) cells in the body. Low NK activity is linked to decreased disease resistance in people with HIV and cancer.
Of course it can be hard to separate out the direct effects of laughter on the body from other factors. Could a good giggle’s immune system benefits be mediated by reducing stress? And since most laughter occurs in the company of others, might its health benefits be due, at least in part, to social interaction and connecting with other people?
There is some evidence that laughter is an analgesic and may induce a dose-related response; but again the question of whether this is due to simple distraction from pain or some inherent chemical benefit remains to be seen.
And finally the “true” scientific answer to does an apple a day keep the doctor away? Only if you aim it well enough.
Have a good one.
mhouston@irishtimes.com
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