Multiple previous studies have associated coffee with better heart health and longer lifespans, although the results for heavy coffee drinkers remained conflicting. New research has now revealed that the time of consumption, more than the amount, determines the health benefits.
The study, published Wednesday in the European Heart Journal, identified two distinct patterns of coffee drinking timing among the participants: the morning drinkers and the all-day types.
Through analysis of dietary data, the researchers concluded: “Drinking coffee in the morning may be more strongly associated with a lower risk of mortality than drinking coffee later in the day.”
Around 36 percent of participants were morning coffee drinkers (drinking primarily before midday), 16 percent drank coffee throughout the day, and 48 percent were not coffee drinkers.
“Research so far suggests that drinking coffee doesn’t raise the risk of cardiovascular disease, and it seems to lower the risk of some chronic diseases, such as type 2 diabetes,” lead author Lu Qi said in a statement.
“Given the effects that caffeine has on our bodies, we wanted to see if the time of day when you drink coffee has any impact on heart health.”
The study tracked the coffee intake of 40,725 participants between 1999 and 2018. The research team then linked this information with records of deaths and causes of death over a period of almost ten years, including 1268 cardiovascular disease deaths and 934 cancer deaths.
Compared to non-coffee drinkers, morning coffee drinkers were 31 percent less likely to die of cardiovascular disease and 16 less likely to die of any other cause. These benefits applied for both moderate (1 to 3 cups) and heavy coffee drinkers (more than 3 cups per day).
However, for all-day coffee drinkers, no health benefits were recorded regarding mortality, regardless of number of cups they consumed.
“A possible explanation is that consuming coffee in the afternoon or evening may disrupt circadian rhythms [the body’s internal clock] and levels of hormones such as melatonin,” Qi said. “This, in turn, leads to changes in cardiovascular risk factors such as inflammation and blood pressure.”
In an accompanying editorial, Professor Thomas Lüscher from Royal Brompton and Harefield Hospitals in London explained the issue further.
“Why would time of the day matter?” he asked.
“In the morning hours there is commonly a marked increase in sympathetic activity as we wake up and get out of bed, an effect that fades away during the day and reaches its lowest level during sleep.”
Lüscher agreed with the authors that the stimulating effects of coffee can disrupt the body’s natural rhythm, noting that 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,” Lüscher said.
He concluded that “the now substantial evidence” shows drinking coffee earlier in the day is likely the most healthy.
“Thus, drink your coffee, but do so in the morning!”