The EU Caffeine and Health study will give coffee lovers a few jitters. Laura Slattery reports
It may be hard to believe, but there was once a time when cappuccinos were considered exotic and if you ordered a tall latte in a café you would be met with a blank look.
Nowadays, most consumers have learned the language and the etiquette of the new generation of coffee house franchises such as Café Sol, Insomnia and West Coast Coffee.
The world's largest coffee chain, Starbucks, is expected to launch into the Irish market later this year, meaning ever more consumers will be shoving their way from the pay counter to much-coveted Central Perk-esque couches, where they can smell the aroma, dip their noses in the froth and get their caffeine fix.
But before they eagerly ingest creamy mochas, caramel macchiatos and americanos with extra shots of espresso, coffee drinkers might want to take note of the findings of a three-year research programme on Caffeine and Health funded by the European Commission.
Long-term caffeine consumption could be responsible for one in 10 deaths from coronary heart disease and one in five deaths from stroke, according to the results of the study.
These figures have been extrapolated on the basis of the finding that a single cup of coffee can elevate blood pressure by 4-5 mmHg (milligrams of mercury).
This is a modest but significant rise, according to Prof Jack James, head of the department of psychology at NUI Galway, who co-ordinated the project. Over a lifetime, it can result in an increased risk of cardiovascular disease.
"We know that an increase of 1 mmHg will translate into an increase in coronary heart disease of 3.5 per cent and an increase of 5 per cent in stroke," says Prof James. "So the implications for the population as a whole are very serious."
Even more worryingly for regular coffee consumers, Prof James believes that the project's findings on caffeine-related deaths are "a conservative estimate".
Stressed-out office workers seeking an immediate coffee buzz may find that the short-term effects of just one serving seem less noticeable over time - they become less prone to the "coffee jitters".
But the EU research disputes the belief among the medical profession that over time people develop tolerance to the long-term cardiovascular effects of caffeine.
As well as measuring the acute and chronic effects of caffeine on blood pressure, the NUI part of the EU Caffeine and Health project examined the effects of dietary caffeine on performance and mood.
Most people believe that caffeine, as a stimulant, improves mental performance and gives them the much-needed mood lift that propels them into work in the morning, with trips to the kettle or the café keeping them alert throughout the day.
But any mood and performance benefits are deceptive, says Prof James, as the caffeine intake is merely relieving withdrawal symptoms of a caffeine dependency that can develop within days.
"Most people start off with a cup of coffee in the morning, drink it intermittently during the day and then it tapers off in the evening. They don't have any just before they go to bed. By the time they wake up in the morning, they go into the early stages of caffeine withdrawal.
"The sensation for the consumer is that they now feel better, but they are just being restored to the way they would be feeling if they had never had the caffeine in the first place."
So the effect is real, but the enhancement is an illusion.
Companies that manufacture coffee, tea, soft drinks and stimulant drinks claim that their products make people feel better, with some saying they enhance performance.
Prof James predicts that the industry will produce a raft of self-funded studies that will attempt to disprove the EU project's findings, using inferior methodology to come to the conclusion that caffeine is really all right after all.
With so many diet-related scare stories hitting the headlines, consumers are weary of the sometimes conflicting scientific advice and are reluctant to change their habits, taking the "well, everything is bad for you" attitude.
"Everything is okay in moderation" is another commonly held belief.
Many people think that two or three cups of coffee a day is fine: it's only when they find themselves asking for extra espresso shots in their cappuccino and can't sleep at night that they should maybe think about cutting back.
It suits manufacturers to say that caffeine intake has no side effects as long as people don't let their normal use escalate, says Prof James.
But the findings of the Caffeine and Health study in relation to blood pressure are based on the effects of just one cup of coffee.
A person who drinks a couple of cups of even fairly weak tea or a litre of a cola drink per day will also have a moderate rise in blood pressure, meaning these drinkers are at the same increased risk of developing cardiovascular diseases as coffee lovers.
Much of the recent debate about caffeine and health has concentrated on the stimulant drink Red Bull, with the European Commission recently upholding the French government's ban on the drink.
"There's a lot of hypocrisy about this, it has to be said. Red Bull has about the same amount of caffeine in it as a cup of coffee," says Prof James. "There is no logical reason why you can ban Red Bull and leave everything else intact."
The all-island Food Safety Promotion Board, Safefood, has recommended that stimulant drinks should not be used for rehydration in association with sport or exercise, nor should consumption by children or in conjunction with alcohol be encouraged.
Safefood's stimulant drinks committee is expected to make further recommendations before new EU labelling rules come into effect in July.
The new rules mean that drinks with a caffeine content greater than 150 mg per litre must be labelled "high caffeine content" and the amount of caffeine present stated.
The table opposite, used by Safefood in its review of the health effects of stimulant drinks, shows the typical caffeine content of some beverages.
The average caffeine content of stimulant drinks tends to be higher per serving. But the caffeine content of tea and coffee can vary greatly depending on the method of preparation, the cup or mug size, the brand and the preferred strength, according to Dr Geraldine Quinn of Safefood.
Other studies have also found that filter coffee has a much higher average caffeine content per serving, higher than the instant variety, and easily within the 150 mg per litre range. But the EU labelling rules do not apply to coffee or tea-based beverages.
Sportspeople and pregnant women (who are advised to keep their daily intake beneath 300 mg) are the two groups of people who usually express concerns about their level of their caffeine intake, says Nuala Collins, a nutrition consultant and VHI dietician.
The general public is not keeping track, she believes.
"With all the supersizing that's going on, people don't often realise that they have increased their caffeine levels," Ms Collins says.
The acute side effects of high caffeine intake include insomnia, anxiety, restlessness and irritability, she adds.
Stop consuming caffeine and dependency can dissipate within a week.
But mild headaches, lack of concentration and other withdrawal symptoms are enough to put most people off the idea of detoxing or switching to decaf, notwithstanding the Caffeine and Health project's links between caffeine and cardiovascular deaths.
"My hope is that we don't frighten people, but that we give them pause for thought," concludes Prof James.
"After all, caffeine is a drug and there is no drug that we know of that does not have side effects. So we shouldn't be surprised."