What is the content of espresso? What kind of coffee has the highest caffeine content?

How much is it? Depending on your body's metabolism, adults weighing 70kg normally drink less than 500mg a day, and it is recommended that you consume about 300-400mg of 4-6 cups of coffee a day.

How much is too much? It depends on how fast your body metabolises caffeine, but as a general rule: "A high dose of caffeine is 500mg per day, based on a 70kg adult, which works out at six to eight cups of instant coffee," says Karen Dickinson, of Body Acoustics Health and Sports Nutrition. "A moderate dose is 300 to 400mg per day; four to six cups."

So how much caffeine is there in common drinks? The following is the caffeine content per 100 ml unit:

Here's how much caffeine (in mg per 100ml) is contained in some of your favourite beverages...

Cocoa Coca-Cola: 9.7 mg/100ml

Instant coffee Instant Coffee: 24.1 mg/100ml

Espresso Espresso Coffee: 173.6 mg/100ml

Hand-brewed pure coffee (black coffee) Plunger Coffee: 45.4 mg/100ml

Decaffeinated coffee Decaf (instant) Coffee: 1.1 mg/100ml

Diet Coke Diet Coke: 12.7 mg/100ml

Energy drink Lift Plus: 14.5 mg/100ml

Energy drink Pepsi Pepsi Max: 19.4 mg/100ml

Energy drink Sugar-free Pepsi Diet Pepsi: 10.1 mg/100ml

Energy drink Red Bull Red Bull: 32 mg/100ml

Energy drink Red Bull Energy drink Red Bull Energy Shot: 133.3 mg/100ml

Tea Tea (white): 6.3mg/100ml

This is an Australian brand energy drink, which has not yet entered V Pocket Rocket Energy Shot: 266.5 mg/100ml in China.