If most people have a strong view on where to get the best cup of coffee, there must be almost as many opinions on the positive and negative effects of one of the world’s most popular drinks.
According to the British Coffee Association, Britons get through more than 98 million cups of coffee every day, but while some people are attracted by the flavour, others are after a caffeine kick.
This chemical – also found in tea and many fizzy drinks such as cola – can make people feel more alert by blocking sleep-inducing chemicals in the brain and increasing adrenaline production.
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However, while these effects can be useful when caffeine is consumed in moderation, too much can leave the drinker feeling “wired”, or shaky and anxious.
Here are some of the pros and cons associated with coffee drinking:
1. Pro: cutting risk of early death
A new study has found that a moderate coffee habit could cut the risk of an early death by up to 31%.
Analysis of 171,000 people in the UK Biobank by a team from Southern Medical University in Guangzhou, China, discovered that those drinking a “moderate” amount, defined as one-and-a-half to three-and-a-half cups of coffee a day, had a lower risk of dying prematurely, irrespective of whether their coffee was sweetened with sugar.
Axios says the results matter because “previous studies have observed coffee is associated with a lower risk of death but didn’t distinguish between unsweetened java and coffee consumed with sugar”.
However, the report “is observational and cannot prove cause and effect”, warned The Times.
“While we can’t conclude definitively that drinking coffee lowers your risk of dying, what we can probably say is that drinking coffee with a little bit of sugar probably doesn’t cause much harm,” said Dr Christina Wee, deputy editor of the Annals of Internal Medicine which published the study.
2. Con: increased anxiety
Overstimulation caused by caffeine can leave some people feeling jittery and anxious.
Researchers at the Maryland-based Johns Hopkins University and the American University in Washington D.C. found that some people suffer from “caffeine use disorder”. Or as study co-author Laura M. Juliano put it: “While many people can consume caffeine without harm, for some it produces negative effects, physical dependence, interferes with daily functioning, and can be difficult to give up, which are signs of problematic use.”
Caffeine can also temporarily raise heart rate and blood pressure, which means anyone who has had a heart attack or been diagnosed with heart disease should reduce their intake to no more than 200mg a day, said Harvard’s Dr Stephen Juraschek. That is around the amount in about two mugs of instant coffee.
3. Pro: cutting risk of disease
“For years, coffee was believed to be a possible carcinogen, but the [United States Department of Agriculture] 2015 Dietary Guidelines helped to change perception,” said The New York Times. “For the first time, moderate coffee drinking was included as part of a healthy diet and when researchers added controls for lifestyle factors, like how many heavy coffee drinkers also smoked, the data tipped in coffee’s favour.”
Earlier this year, data presented at the American College of Cardiology's 71st Annual Scientific Session found that drinking two to three cups of coffee each day lowers your risk of heart disease and dangerous heart rhythms.
The UK Biobank study also found drinking a moderate amount of coffee led to a lower risk of dying from cancer or heart disease.
Other diseases where coffee has shown to have some of the strongest protective effects include Type 2 diabetes, Parkinson’s disease, and liver conditions such as cirrhosis, liver cancer and chronic liver disease.
4. Con: harm during pregnancy
One group that has long been warned to avoid even moderate coffee intake is pregnant women, following studies that suggest high levels of caffeine in pregnancy can lead to babies having a low birthweight, and can even result in miscarriage.
While the NHS says pregnant women should have no more than 200mg per day, or two cups of instant coffee, a research paper published in 2020 suggested there were no safe levels for pregnant women.
The paper, published in BMJ Evidence-Based Medicine which looked at 48 studies on the topic, was described as “controversial” by the BBC.
Professor Jack James, a psychologist at Reykjavik University in Iceland, acknowledged that the work was observational, so could not prove definitively that any caffeine in pregnancy is harmful, but he said analysis, which links caffeine with harm, suggested avoiding drinks like tea and coffee entirely would be the best advice for mothers-to-be and women trying to get pregnant.
The BBC said other experts “strongly disagree, saying this is overkill”, citing the NHS guidelines which, along with the European Food Safety Authority and the American and UK Colleges of Obstetricians and Gynaecologists, recommend limiting, but not eliminating, caffeine consumption during pregnancy.
