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 favourite 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.
Even more sinister links have been made between coffee and ill health. Various studies have concluded that coffee drinkers are more at risk of miscarriage and birth defects, osteoporosis, arthritis and heart disease. So, is our daily cuppa doing more harm than good? 'The findings thus far on coffee intake and health are inconsistent,' says Dr Wendy Doyle from the British Dietetic Association. 'In my mind, the evidence against coffee drinking is poor, unless you're talking about an exceptionally high consumption. In moderation, coffee doesn't appear to cause health problems.'
This was the same conclusion as the authors of the Nurses' Health Study, an epic 25-year study of disease and women's health and lifestyle habits. They reported that 'drinking coffee in moderation appears to have few, if any, adverse consequences.' The study also failed to find evidence to support the link between coffee and increased risk of heart disease and cancer, as well as any difference in the risk of heart disease among women who drank six cups a day compared to those who totally abstained.
Although other research has shown that coffee drinkers who gave up for six weeks lowered their cholesterol level by an average of 5 per cent, coffee proponents point out that since the study didn't distinguish between HDL and LDL cholesterol, i.e. the 'good' and 'bad' types, this total reduction isn't relevant.But experts like Antony Haynes are highly sceptical about many of the recent positive findings. And in spite of unfounded evidence on the negative effects of coffee, the Nurses' Health Study did note that coffee's effect on calcium absorption could make excessive caffeine intake a bad idea for post-menopausal women at risk of osteoporosis. Dr Doyle agrees that the evidence relating to a high caffeine intake and miscarriage is worrying. 'It's wise to keep caffeine from coffee and other sources - such as tea, energy drinks and chocolate - to a minimum if you're pregnant,' she says.
So, despite being one of the most researched beverages around, no one has come up with a definitive 'yes' or 'no' answer to the question of coffee and health. Dr Doyle and Antony Haynes agree on one thing, however. Smoking, lack of exercise and excess alcohol are more serious issues than having a few cups of coffee. 'A daily cup isn't going to do you much harm, but if you want optimum energy and health, you'll be better off without it,' says Haynes. While Haynes might be adamant about the detrimental effects of coffee, the rest of the jury is still out - most likely getting a nice, frothy cappuccino.
For further information on the benefits and dangers of caffeine, you can contact Antony Haynes by email at the Nutrition Clinic at information@thenutritionclinic.com
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