Why the time you drink your coffee is key to protecting your heart

Study finds a morning shot of caffeine reduces cardiovascular risks

A barista prepares a Filipino signature roast coffee bean called Mount Matutum. A study has found that morning coffee drinkers have a lower risk of heart disease. Victor Besa / The National

People who drink coffee in the morning have a lower risk of dying from heart disease than those who drink it throughout the day, or not at all, a new study has found.

Those who enjoyed a morning shot of caffeine were almost a fifth less likely to die from any cause and almost a third less likely to die of cardiovascular disease compared to people who did not drink coffee at all, said researchers in the US.

However, those who drank coffee all day did not experience the same reduction in risk – suggesting the timing may be key. And it may be related to sleep.

The study, which was published in the European Heart Journal, did not explain why morning coffee drinkers were less likely to die from heart disease, but researchers think they may know why.

“A possible explanation is that consuming coffee in the afternoon or evening may disrupt circadian rhythms and levels of hormones such as melatonin. This, in turn, leads to changes in cardiovascular risk factors such as inflammation and blood pressure,” said Dr Lu Qi, professor at the Celia Scott Weatherhead School of Public Health and Tropical Medicine at Tulane University, New Orleans, who led the research.

In an accompanying editorial, professor Thomas Lüscher from Royal Brompton and Harefield Hospitals in London, said there is a marked increase in the body’s sympathetic nervous system, which stimulates the body’s fight or flight response, upon waking. But it fades over time, reaching its lowest level during sleep. So it is possible that coffee drinking in the afternoon or evening disrupts the body’s circadian rhythm, which regulates when we wake and go to sleep.

“Indeed, many all-day drinkers suffer from sleep disturbances. In this context, it is of interest that coffee seems to suppress melatonin, an important sleep-inducing mediator in the brain,” Prof Lüscher wrote. “Overall, we must accept the now substantial evidence that coffee drinking, particularly in the morning hours, is likely to be healthy. Thus, drink your coffee, but do so in the morning.”

Coffee is known to reduce the risk of some chronic diseases, including Type 2 diabetes, so the researchers were keen to find out whether the time of day when you drink coffee had any impact on heart health.

They examined the health records of 40,725 adults taking part in the US National Health and Nutrition Examination Survey (NHANES) between 1999 and 2018, who were asked when they drank coffee, how much and when. The record included a subgroup of 1,463 people who were asked to complete a detailed food and drink diary for a full week, information which researchers used to link with records of deaths and cause of death over a period of nine to 10 years.

More than a third, or 36 per cent were mostly morning coffee drinkers, meaning they primarily drank coffee before midday. Another 16 per cent drank coffee throughout the day, in the morning, afternoon and evening, and 48 per cent did not drink coffee at all.

They found that compared with people who did not drink coffee, morning coffee drinkers were 16 per cent less likely to die of any cause and 31 per cent less likely to die of cardiovascular disease. But there was no reduction in risk for all-day coffee drinkers compared to non-coffee drinkers.

Morning coffee drinkers benefitted from the lower risks whether they were moderate drinkers, consuming two to three cups, or heavy drinkers, who drank more than three cups. People who drank one cup benefitted from a smaller decrease in risk.

“This is the first study testing coffee drinking timing patterns and health outcomes,” said Dr Qi. “Our findings indicate that it’s not just whether you drink coffee or how much you drink, but the time of day when you drink coffee that’s important. We don’t typically give advice about timing in our dietary guidance, but perhaps we should be thinking about this in the future.”

Further studies are now needed to validate our findings in other populations, he said, trials should test the potential impact of changing the time of day when people drink coffee.

A study released late last year found that drinking tea and coffee may also have a “protective effect” against certain types of cancer.

In the study, patients who drank more than four cups of coffee a day were 17 per cent less likely to be affected by a group of “head and neck” cancers, including mouth and throat cancer. One cup of tea a day improved their odds by nine per cent.

Scientists said more work was needed to understand the link, but suggested that “bioactive compounds” found in coffee and tea could slow the spread of disease.