Drinking just three cups of a day of coffee bought from High Street chains could exceed caffeine safety limits, experts warn READ MORE: Man, 34, suffers cardiac arrest 'triggered by drinking daily Red Bull' By Pat Hagan for the Daily Mail Published: 20:00, 26 August 2024 | Updated: 20:01, 26 August 2024 e-mail View comments Takeaway coffees bought from popular High Street outlets contain up to three times as much caffeine as ground coffee brewed at home, a study shows. Consumers who drink just three or four cups a day may exceed the safe daily limit for the stimulant of 400mg, researchers warned. Tests on more than 200 coffees bought from popular chains such as Starbucks and Costa Coffee revealed Americanos had the highest caffeine levels — averaging around 140mg per drink.
Home-made coffees made with one teaspoon of ground coffee per person had the lowest levels — around 23mg. Caffeine is a stimulant which can cause insomnia, nausea, rapid heart rate and headaches when drunk to excess. Tests on more than 200 coffees bought from popular chains such as Starbucks and Costa Coffee revealed Americanos had the highest caffeine levels — averaging around 140mg per drink Caffeine is a stimulant which can cause insomnia, nausea, rapid heart rate and headaches when drunk to excess The findings, published in the journal Nutrients, come just days after a separate team of scientists from Zydus Medical College and Hospital in India found drinking more than 400mg of caffeine a day is .