January 10, 2025
Coffee drinkers may want to reconsider their afternoon and evening consumption: a new study suggests drinking it only in the morning can reduce the risk of heart disease and all-cause mortality.
Led by a team from Tulane University in New Orleans, the researchers behind the observational study looked at the coffee drinking habits of 40,725 adults, including a subsection of 1,463 individuals who completed a more comprehensive food and drink diet questionnaire.
During a median follow-up period of almost 10 years, the morning coffee drinkers were 16 percent less likely to die of any cause, and 31 percent less likely to die of heart disease, than those who didn't drink coffee at all. However, the stats didn't show any reduction in risk for all-day coffee drinkers.
"This is the first study testing coffee drinking timing patterns and health outcomes," says epidemiologist Lu Qi, from Tulane University. "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."
As usual with an observational study, direct cause and effect isn't implied – just a strong association.
The researchers made adjustments for some factors potentially influencing heart health and mortality, including age, sex, physical activity, and sleep patterns, but there are likely many more that they didn't account for, such as genetics.
The risk reduction for morning coffee consumers was similar for those who drank moderately (2–3 cups per day) or heavily (3 or more cups per day). Smaller reductions in risk were seen for light drinkers in the morning group (less than 2 cups).
What this study doesn't look into is why this relationship exists, but there are quite a few possibilities. We know that caffeine has a stimulating effect, and it could be that this is disrupting the body's natural processes during the afternoon and evening.
"A possible explanation is that consuming coffee in the afternoon or evening may disrupt circadian rhythms and levels of hormones such as melatonin," says Qi.
"This, in turn, leads to changes in cardiovascular risk factors such as inflammation and blood pressure."
Numerous earlier studies have linked coffee consumption to positive health effects, whether it's protecting against high blood pressure and strokes, extending lifespan, or reducing the risk of certain types of cancer returning.
There are actually hundreds of different substances in coffee, and scientists are still figuring out what they all are and how they all work on the body. In the meantime, you might want to ease up on drinking it later in the day.
"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," says Qi.
The research has been published in the European Heart Journal.
