The health perks of your caffeine fix

Tea or coffee? To find out which is healthiest, Peta Bee looks at the science behind the benefits of the leaf and the bean.

A DECADE ago, we were the per-capita tea-drinking capital of the world. Nobody guzzled more of it than was consumed in Ireland. Now, though, we have developed a taste for coffee, too.

On average we get through the equivalent of 550 espressos each in a year and consume more java jolts than even the Colombians.

But is switching from leaf to bean a healthy move? After all, tea is renowned for being rich in flavonoids, the powerful oxidant substances known to help fight a range of diseases. 

Coffee, on the other hand, can cause anxiety and sleep problems when consumed in excessive amounts.

Yet experts say the argument is not that clear cut. There are benefits to both. So which to choose? Here we scrutinise the latest evidence to help you find out which daily cuppa will suit your needs.

The health perks of your caffeine fix


In the latest findings from Samsung Hospital in South Korea, data from 25,138 men and women revealed that those who drank three to five cups of coffee a day had the least risk of coronary calcium clogging their arteries, reducing the likelihood of them suffering a heart attack. 

Part of the benefit seems to stem from coffee’s ability to improve insulin sensitivity and blood sugar control which, in turn, reduce the risk of type 2 diabetes, a strong risk factor for clogged arteries.

Earl Grey might be the best choice of tea for your heart health, revealed researchers from Italy’s University of Calabria in the Journal of Functional Foods last year. Earl Grey contains extracts of bergamot which is rich in enzymes known as HMGF (hydroxy methyl glutaryl flavonones) linked to treating heart disease as effectively as drugs like statins.

“Extract from bergamot — most commonly used in Earl Grey tea - reduced total cholesterol, and LDL levels but there was an increase in HDL levels (good cholesterol).

“Therefore a daily supplement of bergamot fruit extract could be very effective for the treatment of high cholesterol,” they concluded.

Flavonoids in ordinary builders tea and green tea have also been linked to boosted heart health.

The health perks of your caffeine fix


Drinking a lot of black tea could help to treat the bone-thinning condition osteoporosis which affects one in three women and one in 12 men at some time in their lives. 

According to a Japanese study published in the journal Nature Medicine last month, an antioxidant called theaflavin-3 present in the humble brew can stop the function of an enzyme called DNA methyltransferase that destroys bone tissue.

Others have produced similarly positive findings. Last year Chinese researchers analysed 14 studies to reveal that people who drink two to three cups of tea a day are 37% less likely to suffer a hip fracture.

They put the benefits down to plant chemicals in tea boosting the building of new bone and the fluoride, calcium and other minerals in a cuppa probably making bones denser and, as a result, stronger.


It’s a close call, but coffee gets the edge in this category. 

A cup or two of the black stuff a day could boost the brain’s ability to store long-term memories, suggested Michael Yassa, a neuroscientist at the John Hopkins University who studied the effects last year. 

He found that people who had a coffee shot after viewing a set of images were better able to pick them out from similar pictures the following day. 

Although Yassa wasn’t sure why this happened, he wrote in the journal Neuroscience that caffeine might raise levels of the stress hormone norepinephrine in the brain, and that might help memories to be retained. 

Spanish researchers suggested that adding sugar to coffee could boost the drink’s ability to enhance memory and attention span.

The health perks of your caffeine fix


Three cups of black tea a day could stabilise blood pressure, according to work by Professor Jonathon Hodgson of the University of Western Australia’s school of medicine. 

He found that after six months, subjects who drank three cups of black tea had up to a 10% lower 24-hour systolic and diastolic blood pressure of between two and three mmHg compared to those who took a placebo drink with the same caffeine content and flavour. 

It’s the flavonoids in tea that are thought to be beneficial. And other recent findings point to tea consumption helping blood pressure. 

At the Preventative and clinical Investigation Centre in Paris two years ago, researchers found that heavy tea drinkers had the lowest blood pressure readings. Interestingly, the highest readings were among those who drank neither tea nor coffee.


Numerous studies have shown that coffee boosts various elements of fitness, including shooting and hitting accuracy in games like tennis and football and power output in sprinting. 

One of the latest, published in the Journal of Applied Physiology in January, suggested it could even motivate you to enjoy workouts. 

About 90 minutes before participants performed a moderate workout on stationary bikes, they were given either 2 x 235ml mugs of black coffee or four mugs of tea.

They later repeated the task with a decaff drink. Researchers found the coffee drinkers all reported the first ride to be easier. 

The findings also suggested coffee can mask hunger as coffee drinkers ate 72 fewer calories at lunch after their workouts. Dr Gill Horgan, a nutritionist who has advised many Irish Olympians, says caffeine has a potent effect on aspects of fitness. 

“It was once a banned substance in sport because of its ability to stimulate the nervous system and boost mental sharpness.” she says. “A lot of people use it as an aid in sport.”


As a good source of the flavonoids, the beneficial antioxidant ingredients that are known to fight diseases including cancer, tea has been the subject of numerous cancer studies and linked to decreased lung and colorectal cancer among others.

Professor Joshua Lamber, a food scientist from Penn State University, recently showed that the flavonoid compound EGCG found in green tea may trigger a cycle that kills oral cancer cells while leaving healthy cells alone. More surprising is that coffee can also help to combat the disease.

In January, scientists from the US National Cancer Institute and Yale University reported how increasing coffee intake could cut the risk of melanoma — the deadliest form ofskin cancer — by one fifth. 

A study of almost 500,000 people found that drinking four cups of coffee a day was linked to a 20% lower risk of developing melanoma. 

Coffee has also been shown to protect against liver cancer and to stimulate positive effects in bile acids that reduce the risk of colorectal cancer. The World Cancer Research Fund concludes that there is no increase risk with moderate and regular tea or coffee consumption.


Although it won’t make the pounds melt away, drinkers of black or green tea are more likely to see their waistlines shrinking than those who prefer other beverages. Japanese researchers found that drinking tea without milk helped to combat the absorption of fat by the body in a study conducted on mice. 

And last year, a study at Penn State College of Agricultural Sciences found that obese mice fed a high fat diet along with green tea extract were able to reduce body weight by 27% and abdominal fat by 36.6% as long as they exercised regularly. 

Exercise or the tea extract alone didn’t achieve such impressive results. 

White tea, made from the buds and young leaves of the tea bush, has been shown in animal studies to inhibit the growth of new fat cells, so may help dieters.


Increasing your daily coffee consumption to two to four cups a day could help to cut the risk of getting Type 2 diabetes, found a 2014 study led by Harvard School of Public Health researchers. In fact, people who increased their coffee intake by more than one cup a day over a four-year period had a 11 % lower risk of the condition.

Cutting down on coffee had the opposite effect, increasing Type 2 diabetes risk by 17%.

It’s not all good news for coffee-drinkers. If you are obese or have high blood pressure, drinking more than three cups a day could double your risk of prediabetes — the early stage of the type 2 condition — reported Italian researchers last year.


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