Drinking up to five espressos a day, or the equivalent, poses no risk to the general population, according to a European review into the safety of caffeine. 

The European Food Safety Authority (EFSA) carried out the scientific study after some countries raised concerns about the health effects of caffeine on the heart and central nervous system, as well as possible risks to foetuses.

The EU agency's review, published on Wednesday, concluded that consuming up to 400 milligrams of caffeine a day "does not give rise to safety concerns for non-pregnant adults", although pregnant women should cap their intake at 200 mg to protect unborn children.

The limit is fairly generous, with average daily intake among European adults aged 18-65 ranging between 37 and 319 mg, according to the agency.

A single espresso contains around 80 mg of caffeine, the same as a standard can of energy drink such as Red Bull, while a black tea has around 50 mg and a can of cola 40 mg.

The view of the EFSA echoes that of the U.S. Food and Drug Administration, which has also cited 400 mg of caffeine daily as an amount not generally associated with negative effects.