Spicy food eaters are addicted to pain
by LEIGH DAYTON , SYDNEY
Curry lovers may be physically addicted to their favourite food, claims a scientist who has studied capsaicin, the 'hot' ingredient in chilli. John Prescott of the CSIRO, Australia's national research organisation, says capsaicin does not have a flavour of its own, but adds to the 'flavour impact' of foods. Its effect on the body's chemistry may enhance the appreciation of hot, spicy flavours.
Capsaicin is found in red peppers, chilli peppers and other members of the capsicum group. It causes a sensation of burning pain in the mouth by triggering the trigeminal nerve, which has branches in the eyes, nose, tongue and mouth. In the mouth, the ends of these branches are sensitive to temperature and foreign substances such as capsaicin. Because capsaicin does not activate taste buds, it has no intrinsic flavour.
In order to find out why people willingly subject themselves to the pain of a spicy meal, Prescott and his colleagues at the CSIRO Sensory Research Centre in Sydney looked at how different amounts of capsaicin affected the flavour and intensity of solutions of sucrose and sodium chloride, which stimulate two of the four basic tastes, sweet and salt (the others are sour and bitter).
Prescott's team selected 35 people who all ate spicy food regularly, but who were not brought up in a culture in which they ate such foods exclusively. The researchers gave 19 people a total of 32 solutions which contained different amounts of capsaicin and sucrose at either body temperature or room temperature. The other 16 people were asked to taste and rate 32 solutions of capsaicin mixed with sodium chloride, also at body or room temperature. The amount of capsaicum in both the sweet and salty solutions ranged from zero to 8 parts per million.
Prescott's key finding was that capsaicin, in any amount and at body or room temperature, increased the overall intensity, or perceived strength, of the solutions. Capsaicin seems to provide a 'big boost' of intensity which salt or sugar cannot provide alone, says Prescott.
He says that the flavour hit may arise because capsaicin triggers the release of endorphins, the body's natural painkillers. Endorphins can create a sense of pleasure or wellbeing, so when food contains capsaicin, the experience of eating is more intense and the food seems more highly flavoured, says Prescott.
Another finding of the team is that, at both temperatures, the capsaicin decreased the perceived sweetness of the sucrose solutions. But the amount by which it was reduced did not depend on the amount of capsaicin. 'As you increase the burn, you don't get more suppression of sweetness,' says Prescott. The reason, he suspects, is that the effect is not a 'true suppression'. Rather, the pain which is triggered by capsaicin may act to divert the brain's attention from the processing of information about sweetness.
In contrast, the scientists found that capsaicin had no effect on the perception of the saltiness of sodium chloride. Prescott suggests the reason is that sodium chloride activates taste receptors on the tongue and stimulates the trigeminal nerve only slightly. The additional stimulation by the capsaicin was not sufficient to distract from the taste.
Although it is unlikely that eating too many spicy foods will damage the trigeminal nerve, Prescott warns of another possible danger. Because people get a definite buzz from capsaicin and because they become used to exposure to increased levels of the the endorphin it stimulates, eating spicy food can be addictive. 'The first bite of mild curry leads on to the vindaloo,' he cautions.