The risks from caffeine from all dietary sources have been assessed by the EU for the first time and it seems more than four espressos could be harmful.

Drinking the caffeine equivalent of more than four espressos a day is harmful to health, especially for minors and pregnant women.

"It is the first time that the risks from caffeine from all dietary sources have been assessed at EU level,", the EU's EFSA food safety agency said on Wednesday.

The agency recommended that an adult's daily caffeine intake remain below 400mg a day.

Deciding a recommended limit was a request of the European Commission, the EU's powerful executive body, in an effort to find a Europe-wide benchmark for caffeine consumption.

"Caffeine intakes from all sources up to 400mg per day consumed throughout the day do not give rise to safety concerns for healthy adults in the general population, except pregnant women," the European Food Safety Authority said in its 120-page report.

Expectant mothers should not exceed half that amount, the agency added, while children should consume no more than 3mg per kilogram of body mass, the agency said.

Beyond the consumption of espressos and lattes, the report also took a closer look at the consumption of Red Bull-style energy drinks that are especially popular with the young.

"The main message of the report is that consumers must account for caffeine consumption from sources other than coffee," an EU spokesman said.

"The health risk is not enormous, but it exists," he added.