Some researchers think coffee could reduce your risk of mouth cancer, while other studies show it may have surprising gut and brain benefits.
And now, a study which looked at data from over 40,000 adults has linked the habit to a longer life.
The research, which was led by scientists at the Tulane University, has been published in the European Heart Journal.
Its lead author, Dr Lu Qi, said: “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.”
How did coffee appear to affect longevity?
Researchers looked at data from participants of the US National Health and Nutrition Examination Survey (NHANES). The data was from 1999-2018.
People in the study were asked to self-report everything they ate and drank, and when.
36% of the participants said they were morning coffee drinkers, while 16% drank coffee throughout the day. 48% did not drink coffee at all.
The experts followed up on the participants for almost a decade after the initial information was collected. During that time, 4,295 people in the study died.
After taking into account various factors like caffeinated and decaf coffee, sleep, and other confounders, the researchers found that in comparison to people who didn’t drink coffee at all, morning coffee drinkers were 16% less likely to die of any cause and 31% less likely to die of cardiovascular disease.
There was no difference between all-cause or cardiovascular mortality risk between all-day coffee drinkers and non-coffee drinkers, though.
Moderate morning coffee drinkers (two to three cups) and heavy morning coffee drinkers (three or more cups) had the same risk reduction, while light morning coffee drinkers (one cup) fared best of all.
“This is the first study testing coffee drinking timing patterns and health outcomes,” Dr Qi said.
“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.”
Does that mean not drinking coffee is deadly?
Absolutely not. This was an observational study, which means scientists didn’t intervene by, say, getting someone who doesn’t drink coffee to start doing so.
That means they could only find a link between coffee and mortality and did not prove one thing definitely led to another, which Dr Qi acknowledges.
“This study doesn’t tell us why drinking coffee in the morning reduces the risk of death from cardiovascular disease,” he 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.”
In an editorial note accompanying the paper, Professor Thomas F. Lüscher from Royal Brompton and Harefield Hospitals said that “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.”
So later coffee drinkers may disrupt their body’s natural sleep patterns, he suggests.
“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!” he added.
