Myths of Coffee

Various people say their brain doesn't start working properly in the morning until they have had a cup of coffee. But the stimulating effect for which caffeine is famous may be an illusion, say researchers. Those who drink a lot of coffee may feel more alert after their first cup of the day. But this is probably because it reverses the fatiguing effects of overnight caffeine withdrawal.

The study suggested that coffee drinkers may actually be better off without their habitual morning mug as it raises the risk of anxiety and high blood pressure. With 379 people who abstained from caffeine for 16 hours before drinking either caffeine or a placebo (dummy drink) were tested for a range of responses afterwards.

Peter Rogers, from the university's department of experimental psychology and one of the lead authors of the study, said: 'Our study shows that we don't gain an advantage from consuming caffeine - although we feel alerted by it, this is caffeine just bringing us back to normal. On the other hand, while caffeine can increase anxiety, tolerance means that for most caffeine consumers this effect is negligible.

Around half the volunteers drank little or no caffeine and the other half were medium-high caffeine consumers. All were asked to rate their levels of anxiety and alertness and whether they had a headache before and after being given the caffeine or the placebo. They were also asked to carry out a series of computer tasks to test their levels of memory, attentiveness and vigilance. The medium who-high caffeine consumers who received the dummy drink reported a fall in alertness and an increase in headaches, neither of which were reported by those who received caffeine. However, their post-caffeine levels of alertness were no higher than those of no or low-level consumers received a placebo. This suggests caffeine only brings coffee drinkers back up to 'normal'.

This effect is not only found with subjects in a low state of alertness such as night- shift workers, or those who wake-up early in the morning, but is additionally found in subjects who already have a high state of alertness. Therefore, coffee when consumed in moderation, four-five cups per day, is safe. Pregnant women should be mindful of the advice given by the Food Standards Agency and limit caffeine intake to 200mg per day from all sources.