Friday, 25 December 2009

The Buzz on Caffeine by Sam Murphy

The buzz on caffeine
by Sam Murphy
Confused about all the conflicting research on coffee and its effect on your health? Sam Murphy investigates the perks and dregs of your daily cup

Before you sit down to read this, why not go and get yourself a nice cup of coffee? You'll be in good company: 400 million cups of the stuff are drunk daily around the world. We Brits alone spend roughly £850 million a year on our morning cappuccinos, lattes and espressos. Aside from tasting good (and smelling even better), coffee is believed to have a number of health benefits. You may not need a man in a white coat to tell you that your daily dose of caffeine counteracts fatigue and improves alertness and concentration, but did you know that research suggests coffee can lessen the risk of heart disease, Parkinson's disease and gallstones as well as act as a powerful antioxidant and increase physical endurance? So is caffeine a health booster that actually tastes good? Well, not necessarily. For every researcher or health expert downing a double latte, there's another ordering green tea. What are we to think?

Coffee gets its kick from caffeine, one of a group of naturally occurring plant-derived compounds called methylxanthines. Caffeine is a drug, pure and simple. It's addictive - too much can be toxic (although no one has ever died of a caffeine overdose) - and withdrawal causes side effects such as headaches and dizziness. When ingested, caffeine has a 'global' effect, meaning it influences all body tissues, including muscle. Read about its effect on exercise. 'Drinking a cup of coffee stimulates the central nervous system and prompts the adrenal glands to release adrenaline, one of two hormones released in response to stress. Your heart beats faster, glucose is released into the blood stream and you feel energised,' explains Antony Haynes, a nutritionist at the Nutrition Clinic in London's Harley Street. 'In the short-term you feel revived, but over time this repeated stress response frazzles the adrenal glands, while the liver becomes conditioned to metabolise caffeine more quickly, meaning you'll need even more cups of coffee to get the same lift.'
In fact, even if you drink only one cup early in the day, caffeine is still at work on your system hours later. A recent study at the Duke University Medical Center in America, found that levels of adrenalin and noradrenaline remained elevated at night even when subjects had slurped their last cup of coffee at lunchtime - in effect, mimicking 24-hour stress. And that's not the only charge Haynes levels at the world's second favorite drink, after tea. 'Coffee is an anti-nutrient,' he says. 'It hampers the absorption of essential minerals including iron, magnesium, zinc and potassium, as well as the B vitamins.' So, for example, drinking a cup of coffee while eating a hamburger can reduce the amount of iron you absorb by 40 per cent, while zinc absorption is reduced if coffee is drunk within an hour after a meal.

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