The Morning Brew: Is Your Daily Coffee Habit Boosting Your Health?

We explore recent headlines that suggest consuming coffee prior to noon may decrease your risk of mortality related to heart issues.

Published 17 January 2024

You may relish a cup of coffee to feel more alert in the morning, but could it also be beneficial for your cardiovascular health?

In January, UK newspapers highlighted research indicating that morning coffee may lower the odds of succumbing to a heart attack or stroke by nearly one third.

While coffee has earlier been associated with a diminished risk of heart and vascular diseases, it remained uncertain whether heavy consumers (more than 3 to 5 cups daily) also experience a lower risk.

Nevertheless, investigators behind a new publication in the European Heart Journal have asserted that the timing of coffee consumption is what truly matters, not the quantity.

Their investigation analyzed data concerning the amount of caffeinated and decaffeinated coffee consumed daily by around 40,000 adults in the United States.

Approximately 36 percent of participants primarily consumed coffee in the morning (between 4am and 12pm), 16 percent drank it at various times throughout the day, and 48 percent abstained from coffee entirely. None of the participants had cardiovascular disease at the outset of the study.

They discovered that individuals who predominantly consumed coffee in the morning were 31 percent less likely than non-coffee drinkers to die from heart or vascular disease over an average of 10 years, and 16 percent less likely to die from any cause.

In contrast, those who consumed coffee throughout the entire day did not show a significantly lower likelihood of mortality over the next decade compared to those who consumed no coffee.

While morning coffee drinkers exhibited a reduced risk of mortality regardless of their daily consumption, those who had 2 to 3 cups in the morning presented the least risk – they were almost half as likely to die from heart or circulatory disorders as those who abstained.

The study further investigated the risk of mortality from cancer but found no significant effect of coffee consumption at any time of day on this risk.

What did the researchers state? 

The researchers indicated that consuming caffeinated coffee in the afternoons and evenings might disrupt individuals’ circadian rhythms. They remarked that earlier studies have demonstrated that late-day coffee consumption can diminish levels of melatonin, a hormone that regulates the sleep cycle.

They noted that this may have mitigated any additional benefits coffee could provide, as there is evidence linking lower melatonin levels to a heightened risk of heart and vascular diseases.

However, the researchers clarified that this rationale does not apply to decaffeinated coffee, which does not influence melatonin levels.

Additionally, the researchers mentioned that drinking coffee in the morning might lower the risk of dying from heart and vascular diseases, as both decaffeinated and caffeinated coffee contain compounds that may reduce bodily inflammation.

Chronic inflammation correlates with an increased risk of fatty deposits (plaques) forming in blood vessels, potentially leading to a heart attack or stroke.

The researchers proposed that morning coffee drinkers may derive the most benefit from coffee’s potential anti-inflammatory properties since certain inflammatory molecules in the bloodstream are more active during the earlier parts of the day.

However, further investigation is required to substantiate if coffee can directly diminish bodily inflammation.

How reliable was the research?

The study was observational, meaning while it demonstrated that people who only consumed coffee in the morning had a lower mortality risk, it cannot definitively prove that drinking coffee caused this outcome.

The researchers controlled for numerous factors that could have also influenced heart and vascular risk, including age, cholesterol levels, blood pressure, and sleep duration.

Nevertheless, they acknowledged there may be other aspects they did not account for. For instance, individuals working night shifts – who have a greater risk of heart issues – may prefer coffee later in the day.

Moreover, although the study involved a large population, it relied on self-reported data. In the study, 40,725 participants were requested to document everything they consumed over the past 24 hours during three separate instances across several years, along with an additional 1,463 participants who recorded their consumption over the last 7 days, twice approximately 6 months apart.

This method of data collection could influence the reliability of the findings, as individuals may misremember precisely when and how much coffee they consumed throughout the day.

How was the media coverage?

Numerous UK media outlets reported on the study, including The Guardian, the Daily Mail, The Times and The Telegraph.

While all these newspapers indicated that the findings may be attributed to coffee influencing melatonin levels and disrupting sleep, only The Guardian highlighted that the study involved decaffeinated coffee, which would not have this impact.

Additionally, the Daily Mail’s headline, suggesting that consuming coffee at a certain time could “slash the risk of a heart attack and stroke by a third,” was incorrect. The study specifically examined individuals’ risk of dying from heart or circulatory diseases such as heart attacks or strokes.

The BHF conclusion

“We are already aware that moderate coffee consumption, about 4 to 5 cups daily, is generally acceptable for most individuals and does not appear to adversely affect heart health. Nonetheless, this study implies that the timing of coffee drinking is essential,” states Tracy Parker, a Senior Dietitian at the British Heart Foundation.

“It’s vital to understand that this type of study cannot establish causation, so we cannot definitively conclude that enjoying a cup of coffee with breakfast will directly lower your chances of dying from a heart attack or stroke.

“Regardless, having your coffee earlier in the day rather than late at night is unlikely to be detrimental and could positively influence your heart health,” she advises.

If you notice that drinking coffee in the afternoon or evening impacts your sleep, consider reducing your caffeine intake or switching to decaf post-midday to aid in achieving a better night’s rest.

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