Is it wise to be so full of beans?

Professionals and researchers examine the benefits and potential hazards of caffeine.

Caffeine can help boost endurance, speed and strength for athletes, research suggests.

We are a nation of caffeine lovers. But is our cup of coffee good for us? What is it doing to our health? We asked the experts.

Coffee can be good for cardiovascular health

High intakes of caffeine are known to increase secretion of the stress hormone cortisol, which in turn can prompt your blood pressure to rise and your heart to beat faster. Some people with a high sensitivity to caffeine may find they experience palpitations after drinking a single cup of coffee — and if that’s you, it is probably wise to limit your intake.

In general, though, the effects are temporary and diminish over time if you consume coffee regularly. Victoria Taylor, a dietitian for the British Heart Foundation, says moderate amounts of coffee (about four cups a day) are fine for most people. “Research shows that this level of caffeine intake shouldn’t be detrimental to your heart health,” Taylor says.

Some recent research has even suggested that moderate to high coffee intakes may have health benefits. Last year US researchers at the National Cancer Institute in Maryland analysed the health data of almost 500,000 Britons and reported the risk of death from any cause, but particularly from cardiovascular disease and cancer, declined steadily as coffee consumption increased.

Best protected were those consuming a regular six or seven cups of coffee a day, who were 16 per cent less likely to die from any disease during the 10-year study.

It is thought to be the antioxidants in the coffee, rather than the caffeine, that offer the health ­benefits.

How many cups is too many?

The European Food Safety Agency recommends we consume no more than 400mg of caffeine — about four cups a day. Even that amount, however, may be too much for some people. Roel Vaessen, secretary-general of the Institute for Scientific Information on Coffee, a not-for-profit organisation, says we are genetically programmed to metabolise coffee at different rates.

“For some people three cups a day is sufficient, while others can tolerate closer to eight or nine cups,” he says.

“If you feel you have had enough, then you probably have.”

Is caffeine really addictive?

Caffeine in itself is not an addictive substance, but it does create a dependency even when a relatively small amount is consumed on a regular basis.

As little as 100mg of caffeine — the amount in a small cup of instant coffee — can lead to physical dependence in some people and at least 50 per cent of regular caffeine consumers suffer from withdrawal symptoms such as headaches, shakes and nausea if they abstain.

“Our tolerance of it varies and increases the more of it we drink,” says Samantha Eden, a researcher in the University of Bath’s department for health. Drinking water after your cup of coffee can help. “It dilutes the caffeine in your system so that you don’t get such a hit,” says Eden, “but the only way to reduce your dependence is to gradually drink less.”

Coffee can be ageing

Some experts believe a high intake of caffeine can cause the skin to wrinkle prematurely and a 2014 study by Polish dermatologists showed caffeine slows down collagen production of the skin. “Caffeine also acts as a weak diuretic, which means that the frequency of urination will increase, thereby possibly dehydrating you,” says Adil Sheraz, a consultant dermatologist. “This can result in dry and lacklustre skin.”

Be careful what time you drink it

The time at which you drink coffee influences its outcomes and since some of caffeine’s effects can linger for as long as five hours, an early evening cup can lead to an ­interrupted night’s sleep for some.

“We all respond differently and it is important to work out when coffee can be helpful or a hindrance to you,” says Neil Clarke, a sport and exercise nutrition researcher at Coventry University. You should time your coffee break for 45-60 minutes before a workout, but if you are going to bed you should probably avoid coffee for at least two hours beforehand.

“Its effects peak between 30 and 75 minutes after consuming it,” says Clarke. “You don’t want to be bouncing off the walls.”

Drinking coffee can boost your fitness

Top athletes use caffeine as a ­performance aid and evidence suggests it can help to boost endurance, speed and strength. “A strong cup of coffee can increase stimulation of the central nervous system, making exercise less of an effort,” Clarke explains. He says a dessert spoon of coffee granules may be the optimal amount to consume before a workout. It is not for everyone, however, and the reason could be genetic.

In a study published in the journal Medicine & Science in Sports & Exercise last year, researchers showed that for people who have a particular variant of a gene called CYP1A2, consuming large amounts of caffeine can boost performance because they metabolise the caffeine faster. Those with the gene variant cycled nearly 7 per cent faster after consuming caffeine, but those without it cycled 14 per cent slower.

Coffee may improve mood

A moderate intake of coffee has been linked to better mood. “Caffeine is a powerful drug with stimulating properties,” says Eden. “Caffeine affects the body chemical adenosine, which normally promotes sleep,” says Clarke. “When you consume it, it overrides the receptors in the brain that detect adenosine and makes you more alert.”

Researchers from the Harvard School of Public Health examined the effects on a group of women and found the risk of depression was 20 per cent lower among women who drank four or more cups of caffeinated coffee than among those who drank little or none. But it doesn’t always make people feel better. “At too high a dose, caffeine can have an adverse impact on mood,” Eden says. “It can make people feel nervous, anxious and, in people with conditions such as bipolar disorder, it can induce a state of mania. You must be sensible with your intake.”

Is decaf really a healthy option?

If you feel jittery after caffeine or can’t sleep, then decaffeinated versions are an option. Some decaffeinating methods use synthetic chemicals such as ethyl acetate, but the tiny amounts you get in a serving aren’t considered harmful. Ian Marber, a nutrition therapist, is a fan. “It tastes good and contains only around 0.3 per cent caffeine,” he says. “Yet it retains the beneficial antioxidants that are good for health.”

The Times