December 1, 2005

The British used to be a nation of tea drinkers. Now, with a coffee house on every corner, caffeine is their daily drug of choice but is the bean habit bad for them? Simon Garfield experiences the highs and lows of the new ristretto republic.

I began writing this article after five cups of good coffee, and it turned out to be one of the best articles I had ever written. It had fluency and style, and a narrative drive that gripped the reader from the very beginning and wouldn’t let go until every fact had been digested and every bon mot admired.

Unfortunately, when I read it again after another four cups, I was just irritable, and I began to dislike the people I was sitting with, I wanted to go to the toilet, but above all I wanted to sleep. I could have slept for a while despite the caffeine, but I would have woken up a few hours later in a sweat, so I stuck it out for the day, looking for someone to snap at. Coffee does that to people: the sudden high, the brief period of delusory creativity, the plunging low, the tiredness and anxiety and headaches. And then it does it all again the next day.

But then I read some newspaper stories and I started to wonder if we all shouldn’t be drinking much more. Coffee had gone from being vaguely bad for one’s health to vaguely good: it could reduce cancer risks and other fatal diseases; it provided more antioxidants than fruit and vegetables.

Each month the medical and nutritional journals contained a new bit of research about the effects of caffeine on rat, and most of it seemed to be good news, and not all of it was funded by the coffee industry. But the older journals told a different story, often something scarier, about negative effects on the heart. And that was just caffeine; coffee contains about 2,000 other compounds that may either shorten or prolong our lives.

After thousands of years, no one seemed quite sure what the coffee bean did to us, apart from drive us in increasingly large numbers into coffee shops and improve our ability to make the perfect ristretto at home. Shouldn’t we by now have a clearer message about what it was doing to us over a lifetime?

‘Addiction’ was widely considered to be an inaccurate term in relation to caffeine; the withdrawal symptoms were mild; most people can give up caffeine in a period of a fortnight with no lasting ill-effects and only resistible cravings; it was very hard to overdose on coffee to a fatal degree, as nausea, irritability and frequent toilet breaks take hold long before risky levels are reached; and even all-night exam students seemed to know their limit.

Two years ago, a team of researchers at the Chemical Health Hazard Assessment Division of Health Canada in Ontario conducted an extensive review of recent medical studies into the health effects of coffee, including general toxicity, effects on the heart, impact on young people and the pregnant, on bone strength, and general behavioural consequences in adults.

The team’s conclusion? A big fat shroud of continued uncertainty. Many of the medical papers seemed to talk over each other like drunks at a party. There were a few aspects on which they agreed: coffee raised blood-sugar levels and could be a diuretic, with heady consumption increasing the risk of dehydration.

They found that those who drank a lot became tolerant to its effects. They stated that decaffeinated coffee would eradicate many of the effects of caffeine, but only if the decaffeinating process didn’t add more chemicals than it took away.

The ‘review of reviews’ concluded that women wishing to become pregnant, and those who already were, should limit their intake to below 300mg per day (two or three strong cups), and that even small quantities induced anxiety in primary-school children (evident from the caffeine present in chocolate and soft drinks.

There was the study published earlier this year in Japan’s journal of the National Cancer Institute that suggested a possible connection between coffee drinking and a lower risk of liver cancer. The research was conducted among 334 Japanese men and women, and when all other easily identifiable lifestyle factors (including hepatitis) had been evened out, it was found that those who drank three to four cups per day were about half as likely to develop liver cancer as those who didn’t drink coffee at all.

Meanwhile, a report in the British Journal of Nutrition earlier this year concluded that because of the recent results of coffee research there was now enough evidence to classify coffee as a ‘functional food’: that is, a food that is seen to enhance the quality of life. The beneficial effects of caffeine had been noted in small-scale trials of those with Parkinson’s disease and Alzheimer’s, and two larger studies have also produced good news.

Last year, research published by the Harvard School of Public Health and the Brigham and Women’s Hospital in Boston found that habitual coffee drinkers substantially reduced their chances of developing Type 2 diabetes, the type diagnosed most often after the age of 40 and frequently associate with obesity. The work involved an eight-year observation of more than 40,000 men and 85,000 women, and during this period 1,333 new cases of Type 2 diabetes were diagnosed in men and 4,085 in women. But it was found that those who drank more than six oz cups of caffeinated coffee a day reduced their risk of contracting the disease by 50 per cent (men) and 30 per cent (women).

The second study, which in August prompted heated but misleading headlines suggesting drinking coffee was better for you than eating fruit and vegetables, was delivered to the American Chemical Society by a team of researchers at the University of Scranton in Pennsylvania. This found that coffee provided more antioxidants -–– the enzymes that help prevent cellular damage from free radicals and may limit the growth of tumours, heart disease and rheumatoid arthritis –– than anyother source in the regular adult diet.

In an analysis of more than 100 food items, adults in the Bury absorbed about 1,300 mg of polyphenol antioxidants from coffee, compared with 294mg from tea, 76mg from bananas and 48mg from corn. What this also exposed of course, is that the adults are not consuming enough antioxidants from other rich sources such as grapes, cranberries or nuts, and the researchers were keen to point out that coffee hardly provided the vitamins, minerals and fibre readily available at any greengrocers.

Inevitably, the good news is beset by caveats; the molecular complexities of just one component in coffee may carry both beneficial and detrimental indicators for our health. The distinct antioxidant effect of caffeine –– which should protect against heart disease –– originates from the presence of chlorogenic acid, which is believed to be responsible for the bitterness in coffee. Studies have suggested that this compound is responsible for the higher levels of plasma homocysteine in coffee drinkers, which is a traditional risk factor in heart disease and has been implicated in increasing the risk of dementia and Alzheimer’s.

Of all the current research, he is enthusiastic about the possible protection caffeine may provide against Type 2 diabetes. Much more interventionist research needs to be conducted, he says, but he has little difficulty in plotting a chemical mechanism in which caffeine may work against the disease, partly because it relates to research he conducted a few years ago.

Adenosine stimulates glucose production by the liver, and a Type 2 diabetic produces too much; it follows that inhibition by caffeine of the adenosine function may also inhibit the liver’s capacity to produce glucose.

Last year, when Tony Blair received treatment for his irregular heartbeat and Bill Clinton blamed his friend’s hospitalization on ‘too little sleep and too much coffee’, Cherie Blair announced that she would try to reduce his caffeine intake. Dr Jarvis noticed that her patients immediately began to think about an issue that had seldom concerned them before.

“People look for easy changes in their lifestyle,” she says, “and there was a hope that if they cut out coffee it will be a quick fix and they won’t have to exercise or change other things.” She has found that few of her patients drink the recommended daily intake of water (one-and-a-half to two litres), and is concerned that a reduced coffee consumption will not be compensated for with other fluids.

Dr Jarvis follows the one common line that is detectable from most of the experts and the bulk of the literature: up to 450mg of caffeine per day (four to five cups) will not be harmful to the average adult, 300mg is a safe limit for pregnant women, and young people shouldn’t be encouraged to start drinking too early. “Too much was clearly a bad thing,” she says, “but so is everything, including water.”

It is only certain that coffee science is even now in its infancy, and we are still at that stage where the only reliable experiments are those we perform on ourselves. –– Dawn/Observer Service

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