How much is too much coffee?

The BBC website reports on a teenager who had to be admitted to hospital after overdosing on espresso. This has prompted discussion on how much is too much coffee? The recommendation from the Department of Health (DoH) is not to drink more than five single espressos or seven instant coffees a day. The highest natural caffeine content is found in filter coffee, a mug of which contains about 120mgs of caffeine. Instant coffee contains roughly 75mgs and espresso 107mgs. The British Coffee Association provides more advice on How much caffeine is in your cup?

However, as individuals vary in their sensitivity to caffeine, it is apprently difficult to generalise. So perhaps it is best to stick to Earl Grey tea...