Those who drink coffee in the morning appear to have a lower risk of dying from cardiovascular disease and a lower overall mortality risk compared to those who drink coffee throughout the day, according to research published in the European Heart Journal.

The study involved 40,725 adults who took part in the US National Health and Nutrition Examination Survey between 1999 and 2018. As part of the study, participants were asked about all foods and beverages, including coffee, that they consumed for at least one day. A subgroup of 1,463 people were asked to complete a detailed diary of food and drink consumption for a week. The researchers then linked this information to records of deaths and cause of death over a period of nine to 10 years.

About 36% of people in the study drank coffee in the morning, 16% drank coffee throughout the day, and 48% did not drink coffee. Those who drank coffee in the morning were 16% less likely to they die from any cause and 31% less likely to die from cardiovascular disease compared to those who did not drink coffee. This benefit was seen in both moderate coffee drinkers (2-3 cups) and heavy drinkers (more than three cups). Participants who drank a cup or less of coffee benefited from less risk reduction. In contrast, no reduction in risk was seen for those who drank coffee throughout the day.

Study leader Lu Qi, a professor at the School of Public Health and Tropical Medicine at Tulane University in New Orleans, US, points out that “This study doesn’t tell us why drinking coffee in the morning reduces the risk of dying from cardiovascular disease. A possible explanation is that drinking coffee in the afternoon or evening can disrupt circadian rhythms and hormone levels, such as melatonin. This in turn leads to changes in cardiovascular risk factors, such as inflammation and the blood pressure. But further studies are needed to validate our findings in other populations, as well as clinical trials to test the possible effects of changing the time of day when people drink coffee.”