Need-to-know: should I drink coffee?

After water, coffee is the world’s most popular drink, and in the UK we consume approximately 95 million cups per day1. But is it good for us?

The media is contradictory – some articles tell us to avoid coffee as it dehydrates us, while others sing its praises2. Who to believe? Here we examine five of the most common health queries about coffee.

 1. "It could cause heart problems"

The British Heart Foundation (BHF) says that moderate amounts of caffeine – equivalent to four or five cups of coffee per day (400mg) – “has no effect on your risk of developing coronary heart disease”3, neither does it lead to abnormal heart rhythms. However, caution should be exercised by certain people. BHF dietician Victoria Taylor says: “Some people are more sensitive to caffeine than others and, for some, caffeine can trigger heart palpitations (the sensation of feeling your heart beating abnormally quickly, or irregularly). If this applies to you, then it would be sensible to limit your intake of foods and drinks containing caffeine.”


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2. "It is dehydrating"

One of the most commonly made claims is that coffee (and tea) are dehydrating. According to the British Nutrition Foundation, though: “Drinking tea or coffee also delivers water, and even though these drinks can contain caffeine, in moderate amounts, caffeine doesn’t affect hydration.”4 In other words, unless you’re limiting your beverages to numerous cups of espresso, dehydration shouldn’t be an issue.

 3. "It's a no-go during pregnancy"

Again, moderation is key. High levels of caffeine in pregnancy can lead to babies with a low birth weight – and too much caffeine is also associated with a higher risk of miscarriage5. According to NHS advice, pregnant women should limit caffeine to 200mg a day – the equivalent of two mugs of instant coffee or one and a half mugs of filter coffee. Tea has around 75mg of caffeine per mug. Cola, chocolate and some medicines also contain caffeine and need to be included in your calculations. However, the NHS says: “If you occasionally exceed the limit, don’t worry. The risks are small.”

 4. "It could affect diabetes" 

Here the message gets confusing. On one hand, coffee contains polyphenols, which are believed to help prevent inflammatory illnesses such as type 2 diabetes, and magnesium, which has also been linked with lower rates of the condition6. However, one study found that coffee could lead to decreased insulin sensitivity7, especially in those who suddenly increased their intake. According to, decaffeinated coffee may be the best option for people with diabetes as researchers find it includes the benefits of coffee without some of negative effects associated with caffeine.

5. "It causes tummy troubles"

Around one third of people in one study reported that after drinking coffee they needed to empty their bowels8. This is due to caffeine helping to induce peristalsis, the process that causes your intestines to contract and push food and drink through your gut. For people with IBS (irritable bowel syndrome), which involves more gut sensitivity, this can be problematic and bring on diarrhoea9. Moderation or switching to decaf coffee or green tea should lower the impact.

In short, for most of us, a cup of coffee or two a day is harmless – and may even do us good as some reports associate it with lower incidence of some serious diseases10 – but, as with most things, moderation is key and nothing beats a healthy diet and regular exercise for keeping well. And if you think the stimulating caffeine is affecting your sleep, switch to decaf or limit yourself to drinking coffee and other caffeinated items in the morning.