Is coffee in the morning good for you?

You might enjoy a cup of coffee to help you feel more awake in the morning, but could it also be good for your heart?

In January, UK newspapers reported on research that found that drinking coffee in the mornings could reduce the risk of dying from a heart attack or stroke by almost a third.

While coffee has previously been linked to a reduced risk of heart and circulatory diseases, it’s been unclear if people who drink a lot (more than 3 to 5 cups a day) also have a lower risk.

However, researchers behind a new study published in the European Heart Journal have claimed it’s not how much coffee you drink, but when you drink it that matters.

Their study looked at data on how much caffeinated and decaffeinated coffee around 40,000 adults from the United States drank every day.

About 36 per cent of the people included in the study mainly drank coffee in the morning (between 4am and 12pm), 16 per cent drank it in the morning, afternoon and evening, and 48 per cent did not drink coffee at all. None of them had a heart or circulatory disease at the start of the research.

They found that people who mainly drank coffee in the morning were 31 per cent less likely than non-coffee drinkers to die from a heart or circulatory disease after an average of 10 years, and 16 per cent less likely to die from any cause.

In comparison, people who drank coffee throughout the day did not have a significantly lower risk of dying over the following decade than those who did not have any coffee.

While morning coffee drinkers had a reduced risk of dying no matter how many cups they drank a day, morning drinkers who had 2 to 3 cups had the lowest risk – they were nearly half as likely to die from a heart or circulatory disease as those who drank none.

The study also looked at people’s risk of dying from cancer, but did not find that drinking coffee at any time of day had a significant impact on their risk.

What did the researchers say? 

In the study, the researchers said that drinking coffee with caffeine in the afternoons and evenings may disrupt people’s body clock. They noted that previous trials have shown that drinking coffee late in the day can reduce people’s levels of a hormone called melatonin, which controls the sleep cycle.

They wrote that this could have lessened any other benefits of coffee, as there is evidence that lower levels of melatonin are linked to a higher risk of heart and circulatory disease.

But the researchers said that this explanation would not apply to people drinking decaf coffee, which does not affect melatonin levels.

The researchers also wrote that drinking coffee in the morning might have reduced the risk of dying of heart and circulatory diseases because both decaffeinated and caffeinated coffee contain substances which may reduce inflammation in the body.

Chronic inflammation can increase the risk of fatty material (plaques) building up in the blood vessels, which can lead to a heart attack or stroke.

The researchers suggested that morning drinkers may benefit the most from coffee’s potential anti-inflammatory effects, as some molecules in the blood that cause inflammation are more active earlier in the day.

However, more research is needed to confirm if coffee can directly reduce inflammation in the body.

How good was the research?

The study was observational, which means that while it showed people who only drank coffee in the morning had a lower risk of dying, it cannot prove that this was caused by drinking coffee.

The researchers did adjust for lots of factors that may have also affected people’s risk of heart and circulatory disease, such as their age, cholesterol levels, blood pressure and how much sleep they got.

However, they admitted that there may have been other factors they did not consider. For example, people who work night shifts – who have a higher risk of heart problems – may tend to drink coffee later in the day.

Also, while the study was large, it used self-reported data. In the study, 40,725 people were asked to report everything they had eaten or drunk over the last 24 hours 3 separate times over several years, and 1,463 people also recorded what they had consumed over the previous 7 days, 2 times around 6 months apart.

This method of collecting data could affect the accuracy of the results, as people may have misremembered exactly when and how much coffee they drank during the day.

How good was the media coverage?

Lots of UK media outlets wrote about the study, including The Guardian, the Daily Mail, The Times and The Telegraph.

While all of these newspapers said that the findings may be caused by coffee affecting melatonin levels and disturbing sleep, only The Guardian mentioned that the study included decaffeinated coffee, which would not have this effect.

And the Daily Mail’s headline, which suggested drinking coffee at a specific time of day “can slash the risk of a heart attack and stroke by a third”, was inaccurate. The study actually looked at people’s risk of dying from heart or circulatory diseases such as heart attacks or strokes.

The BHF verdict

"We already know that drinking coffee in moderation, about 4 to 5 cups a day, is generally fine for most people and does not seem to negatively impact heart health. However, this study suggests that the time of day you drink coffee also matters,” says Tracy Parker, a Senior Dietitian at British Heart Foundation.

“It's important to note that this type of study cannot prove cause and effect, so we cannot say for certain that enjoying a cup of coffee with your breakfast will directly reduce your chances of dying from a heart attack or stroke.

“Nonetheless, having your coffee earlier in the day rather than late at night is unlikely to be harmful and could benefit your heart health,” she advises.

If you find that drinking coffee in the afternoon or evening affects your sleep, try to reduce your caffeine intake or switch to decaf after midday to help you get a better night’s rest. 

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