Morning coffee may protect the heart better than drinking coffee all day, study suggests

People who drink coffee in the morning have a lower risk of dying from cardiovascular disease and a lower overall mortality risk than all-day coffee drinkers, according to a study published in the European Journal of the Heart.

The research was led by Dr Lu Qi, HCA Regents Distinguished Chair and Professor at the Celia Scott Weatherhead School of Public Health and Tropical Medicine at Tulane University, New Orleans, USA.

He said: “Research so far suggests that coffee consumption does not increase the risk of cardiovascular disease and appears to reduce the risk of some chronic diseases, such as type 2 diabetes. Considering the effects of caffeine on our bodies, we wanted to see if the time of day you drink coffee had an impact on heart health.

The study included 40,725 adults who participated in the US National Health and Nutrition Examination Survey (NHANES) between 1999 and 2018.

In the study, participants were asked about all the foods and drinks they had consumed on at least one day, including whether, how much, and when they drank coffee. The study also included a subgroup of 1,463 people who were asked to complete a detailed food and drink diary for a full week.

Researchers were able to link this information to records of deaths and causes of death over a period of nine to ten years.

About 36% of people in the study drank coffee in the morning (they mostly drank coffee before noon), 16% of people drank coffee throughout the day (morning, afternoon and evening), and 48% of people drank coffee throughout the day (morning, afternoon and evening) were not coffee drinkers.

Compared to people who didn’t drink coffee, morning coffee drinkers were 16% less likely to die from any cause and 31% less likely to die from cardiovascular disease. However, there was no reduction in risk for all-day coffee drinkers compared to non-coffee drinkers.

Morning coffee drinkers benefited from lower risks, whether they were moderate drinkers (two to three cups) or heavy drinkers (more than three cups). Light drinkers in the morning (one cup or less) benefited from a smaller reduction in risk.

Dr Qi said: “This is the first study testing coffee drinking habits and health outcomes. Our results indicate that it’s not just whether or how much you drink coffee, but also the time of day you drink coffee that is important. We don’t usually give advice on the timing of our dietary recommendations, but perhaps we should think about it in the future.

“This study does not tell us why drinking coffee in the morning reduces the risk of death from cardiovascular disease. One 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.

“Additional 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 people drink coffee.”

In an accompanying editorial, Professor Thomas F. Lüscher of the Royal Brompton and Harefield Hospitals in London, UK, said: “In their study published in European Journal of the HeartWang (and colleagues) analyzed the time of day coffee is consumed among 40,725 adults from NHANES and 1,463 adults from the Women’s and Men’s Lifestyle Validation Study.

“Over a median follow-up of nearly a decade, and after adjusting for caffeinated and decaffeinated coffee consumption, daily cup quantities, sleep hours, and other confounding factors, the morning rather than that of the entire day, was significantly associated with lower risks of all-cause mortality with a relative risk of 0.84 and cardiovascular mortality even of 0.69 compared to non-coffee drinkers.

“Why should the time of day matter? In the morning, there is usually a marked increase in sympathetic activity when we wake up and get out of bed, an effect that fades during the day and rises to its peak lowest during sleep. Thus, it is possible, as the authors point out, that coffee consumption in the afternoon or evening disrupts the circadian rhythm of sympathetic activity.

“Indeed, many daily drinkers suffer from sleep disorders. In this context, it is interesting to note that coffee appears to suppress melatonin, an important sleep mediator in the brain.

“Overall, we must accept the now substantial evidence that drinking coffee, particularly in the morning, is likely to be healthy. So, drink your coffee, but do it in the morning.”