Coffee drinkers are woefully ignorant of the dangers lurking in their cup, as there is almost no information on the caffeine contents of the various types of commercially prepared coffees, a new report has warned.

It suggested that consumers should be provided with information about the caffeine content of their takeaway latte or espresso since most are unaware of how it varies in strength from shop to bar or from cup to mug.

The report stated pregnant women, as well as people with health problems, need to limit their caffeine intake.

It indicated that there is a risk of poor foetal growth and miscarriage linked to caffeine consumption of more 300mg a day, the Independent reported.

“For some, coffee is a problematic commodity because it is sold without information about caffeine, or a warning if it contains a lot,” said Professor Mike Lean, head of human nutrition at Glasgow University, who wrote the report.

He called on the Food Standards Authority to carry out a national study of the range of caffeine contents, reasons for variations and consumption habits to improve information for consumers.

Writing in the current issue of the medical journal Maturitas, he also warned that the caffeine content of some coffees could be six times higher than others.

The report comes after a survey on a sample area of shops in Glasgow, found that the caffeine content of espresso coffee, routinely used to make latte and cappuccino, varied widely, from 51mg to 322mg a cup.