A friend recently showed me an article that advised that a cold drink with food was not a good idea, because it not only diluted the stomach acid, but the coldness also thickened the partially digested food, making its onward movement more difficult for the gut.

What an unpleasant thought!

However, it reminded me that my Thai friend's father always advises against iced drinks, and I have concluded that it makes good sense. If your normal body temperature is 37 degrees Celsius then it is obviously wrong to try to reduce it in the forlorn hope of feeling cooler. Any respite you may feel is temporary at best, and the effect is largely psychological, not physical.

Which brings me to another question: why is so much ice put into drinks at fast food outlets? These are not my favourite places, but the answer is simple. It saves them money. Frozen water is cheaper than the drink itself, so plenty of ice means that the drink costs them less. You end up paying for a container full of ice that is rapidly diluting the small amount of drink. Try asking for a drink without ice and they look really unhappy, and may give you only half a glass.

So now you know. Cold drinks are no good for either your stomach or your pocket!

John Kelly is the director of Mentor International.

E-mail www.mentor.ac.