Scottish researchers worked with scientists from the two mainland European countries to test 100 espressos, as well as cappuccinos and instant coffees.
And the cups of coffee in Glasgow were the strongest. Caffeine levels in the city’s espressos ranged from 72mg to 212mg, compared with 73-135mg in Italy and 97-127mg in Spain.
The caffeine content of cappuccinos bought in Scotland varied from 101-275mg per cup.
Glasgow University scientists have warned coffee lovers that simply counting cups is not an accurate guide to how much caffeine they are consuming.
Health experts say up to 300mg a day for an adult is a safe amount, with over-consumption leading to restlessness, irritability, stomach upset, a rapid heartbeat and muscle tremors.
Previous Glasgow University research has shown that caffeine levels can vary wildly from shop to shop, from 50mg to 300mg per espresso, breaching the 200mg recommended safe limit for pregnant women.
Explaining their findings, the researchers said coffee in Scotland usually used more heavily roasted beans and the serving sizes were larger.
Michael McCracken, whose firm Fun In a Cup trains coffee shop baristas, said people often made a false connection between caffeine levels and flavour.
He said: “There are two main types of coffee bean produced, arabica and robusta, and arabica is the higher quality bean but contains roughly half the caffeine of robusta.
“So when you go into general restaurants and cafés that use Italian coffee, they tend to have high levels of robusta, anywhere between 30 and 70 per cent, which boosts caffeine levels considerably. But if you go into specialist coffee houses, they use 100 per cent arabica, and it’s about flavour rather than strength.”
Mr McCracken said flavour was not a reliable guide to the strength of a coffee.
Kris Mutter, manager of coffee house Tapa in Glasgow’s South Side, said people tended to equate a bitter taste with strength.
He said: “We do get people who say that the coffee’s not strong enough, but it’s because we roast our own beans. This takes away the bitter edge that they tend to get in high street shops and gives the coffee a smoother flavour without removing the strength.”
Customer and coffee lover Christina Tweeddale, 25, said she looked for flavour rather than strength.
She said: “I come here for the flavour, but I also enjoy the coffee I get at Artisan Roast, though if I have a cup there, I’ll be buzzing all day.
“But it’s all about the taste, and I do watch my intake and try to keep it down to a cup a day, If I overdo it, I have trouble sleeping.”
Emma Lindsay, 25, who works at the Glad Café, also in the South Side, said customers could be fussy about their coffee, preferring an involved process called the Aeropress, which allows them to set their own strength. She said: “We do get people who really know what they want, but it’s about flavour. Sometimes they send cups back asking for hot water to be added just because it’s too strong for them.”
Glasgow-based David Bennett, who writes a review blog called Grind My Beans, said coffee houses were upping their game.
“There are places where they believe that you make a good cup of coffee by making it as strong as possible,” he said.
“But I think people are getting better at spotting a good cup of coffee. People I’ve spoken to are much more keen to go somewhere that’s going to provide that for them.”