What Is The Right Time To Drink Coffee? US Study Suggests This Hour Of The Day For Lower Mortality Risk

Researchers from several US universities, including Harvard, look at patterns of coffee drinking timing over 2 decades, and evaluate their associations with all-cause and cause-specific mortality.

Coffee is one of the most commonly consumed beverages in the world.

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A nearly two-decade-long study by US scientists has found that people who drank coffee in the morning had a 31% lower chance of death from heart disease than those who drank it all day (any hour) or those who did not drink coffee at all.

“Drinking coffee in the morning may be more strongly associated with a lower risk of mortality than drinking coffee later in the day,” says the study, published on Tuesday in the peer-reviewed ‘European Heart Journal’.

According to the researchers, the motive behind the study was to identify the patterns of coffee drinking timing among the US population, and evaluate their associations with all-cause and cause-specific mortality.

Coffee is one of the most commonly consumed beverages in the world. Caffeine is not a nutrient; it is a dietary component that functions in the body as a stimulant. Most prospective studies have found that moderate coffee consumption is associated with lower risks of Type 2 diabetes, cardiovascular diseases (CVDs), and death. 

The 2015-20 US Dietary Guidelines recommend moderate coffee consumption as part of a healthy dietary pattern. “Much of the available evidence on caffeine focuses on coffee intake. Moderate coffee consumption (three to five 8-oz cups/day or providing up to 400 mg/day of caffeine) can be incorporated into healthy eating patterns... In healthy adults, moderate coffee consumption is not associated with an increased risk of major chronic diseases (e.g., cancer) or premature death, especially from CVD,” the guidelines state.

How The Study Was Conducted

Scientists from several American universities, including Tulane University in New Orleans and Harvard, studied the effects of drinking coffee in the morning on heart health and death risk of more than 40,000 adults taking part in the US National Health and Nutrition Examination Survey (NHANES) between 1999 and 2018. 

The researchers note in the study that “increasing evidence has indicated the importance of circadian rhythm in regulating human food intake behaviours and metabolism, and some previous studies have shown that the timing of food intake may modify the association of food intake with health outcome”. 

“Intriguingly, coffee has long been used to improve wakefulness and relieve drowsiness due to the stimulating effects of caffeine on the central nervous system. However, drinking coffee later in the day may disrupt the daily circadian rhythms and thus modify the association between the amount of coffee intake and health outcomes,” they add.

Therefore, the scientists looked for and found links between the risk of dying — from anything or specifically heart disease — and participants’ coffee-drinking habits.

How Much Coffee, And When To Drink?

The study says that drinking coffee in the morning may be more strongly associated with a lower risk of mortality than drinking coffee later in the day. Drinking coffee in the morning could come with heart health benefits, compared to drinking it throughout the day or not drinking it at all, according to the study.

Professor Lu Qi from Tulane University in New Orleans, who led the study, said in a statement, “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.” Professor Qi and his team found that morning coffee drinkers were 16% less likely to die for any reason, and 31% less likely to die specifically of heart disease, compared to participants who did not drink coffee. But participants who drank coffee later in the day did not have these lower risks, so timing appeared significant. Particularly low risks were associated with those who drank two, three or more cups of coffee each morning, rather than one.

“This study doesn’t tell us why drinking coffee in the morning reduces the risk of death from cardiovascular disease,” Qi said. “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.”

Coffee Consumption And Circadian Rhythm: The Melatonin Factor

A previous clinical trial showed that heavy coffee consumption in the afternoon or evening was associated with a 30% decrease in peak melatonin production at night-time compared to controls. When consumed in the evening, caffeine might delay the body’s internal clock. An earlier paper published in ‘Science Translational Medicine’ showed that people given a dose of caffeine a few hours before their normal bedtimes exhibited a delay in their circadian rhythms of more than half an hour. Caffeine affects melatonin secretion adversely. Caffeine’s wakefulness-promoting and sleep-disrupting powers upset the hormones such as melatonin that induce calmness — much needed in the evening hours as the body prepares for a night of restful sleep. 

Melatonin is a neuroendocrine hormone with a key role in the circadian rhythm, and some evidence suggests that low levels of melatonin are associated with higher oxidative stress levels, raised blood pressure levels, loss of healthy restful sleep, and enhanced CVD risk.

However, the latest study was observational, i.e. the researchers cannot be sure that drinking coffee in the morning caused the lower risk of heart disease or whether the two were just correlated with each other. “Further studies are needed to validate our findings in other populations, and we need clinical trials to test the potential impact of changing the time of day when people drink coffee,” Professor Qi said. 

Professor Thomas F. Lüscher from Royal Brompton and Harefield Hospitals in the UK wrote an accompanying editorial to the research paper, lauding its strength: “The strength of the study is the large number of individuals included and the long follow-up of almost a decade.”

In conclusion, he 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!”

The writer is a senior independent journalist.

[Disclaimer: The information provided in this article is for general informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare provider with any questions you may have regarding a medical condition or health concern.]