Coffee is one of the most popular beverages in the world, and its potential health benefits have been well documented. The US Dietary Guidelines (2015–2020) recommend that coffee is an essential component of a balanced diet. According to the research, moderate intake may also lower the risk of mortality, cardiovascular diseases (CVDs), and Type 2 diabetes. However, it is uncertain if excessive caffeine intake (3 or more cups per day) impacts mortality.
Recent research clearly shows that circadian rhythms play a critical role in metabolism and feeding habits. Although modern research has shown that caffeine enhances wakefulness, consuming coffee in the later part of the day may have a side effect on health due to disruption of circadian rhythms.
Data from the National Health and Nutrition Examination Survey (NHANES) which is a nationally representative population-based cohort study comprised of participants who are 18 years and above from ten cycles conducted between 1999 and 2018. The subjects with self-reported CVD or cancer, pregnant, or with implausible total energy intake were excluded, leaving around 40,725 participants.
Participants were split into three groups: morning (4 a.m. to 11:59 a.m.), afternoon (12 p.m. to 4:59 p.m.), and evening (5 p.m. to 3:59 a.m.) to assess their coffee intake patterns using 24-hour food recalls. The Women’s Lifestyle Validation Study (WLVS) and Men’s Lifestyle Validation Study (MLVS) were conducted as external validation studies with 772 women and 691 men using seven-day dietary records (7DDR).
To be more specific, the cluster analysis specified the patterns of coffee consumption, which were considered valid based on internal and external criteria. This study used mortality data linked to the National Death Index (NDI) until December 31, 2019, reporting the disease diagnoses in accordance with the International Classification of Diseases (ICD)-10 code.
Hazard ratios (HRs) and 95% confidence intervals (CIs) for mortality risks of coffee drinking patterns were examined by using Cox proportional hazards models adjusted for various covariates such as age, sex, race, income, education, lifestyle, and other dietary intakes. The statistical analyses were conducted using Statistical Analysis System (SAS) 9.4 and Statistical Package for Social Sciences (SPSS) 23.0 statistical software. In the study, the statistical significance of the results was set at P < 0.05.
The study identified two distinct patterns of coffee drinking timing among 40,725 participants from the NHANES: morning-type and all-day-type patterns. Cluster 1 (morning-type): For most participants, coffee intake was mainly from 4 a.m. to 11: 59 a.m., with little intake in the afternoon or evening 37% (4,743 participants). Cluster 2 (all-day type): A total of 6,489 participants drank coffee at some point within the day, morning, afternoon, and evening, contributing to 16%. Whereas 48% of the participants (19,593) were non-coffee consumers.
Morning-type and all-day-type coffee consumers were older, had significantly higher family income, and had a higher prevalence of diabetes, hypertension, and high cholesterol as compared to non-consumers. Morning-type coffee drinkers consumed a smaller amount of total coffee every day (Mean = 458.5 g/day) than all day-type drinkers (Mean = 597.7 g/day).
In the morning-type coffee drinking pattern, the HR for all-cause mortality was 0.88 (95% CI: 0.81 – 0.96, P < 0.01, suggesting a lowered risk of all-cause mortality. After further adjustments, the HR remained significant at 0.87 (95% CI: 0.80–0.95, P < 0.01) and 0.84 (95% CI: 0.74–0.95, P < 0.01). In contrast, the all-day-type coffee drinking pattern did not show a significant association with all-cause mortality, with an HR of 0.99 (95% CI: 0. 90–1.10, P = 0.89), and further adjustments did not alter this result (HR: 0.98, P = 0.74; HR: 0.96, P = 0.62).
In terms of cancer-specific mortality, the morning pattern had an HR of 0.92 (95% CI: 0.77-1.09, P = 0.34), which was not statistically significant. After additional adjustments, the HR remained at 0.91 (95% CI: 0.77-1.08, P = 0.27) and 0.97 (95% CI: 0.75-1.25, P = 0.82), both of which were not of statistical significance. Similarly, the all-day-type pattern had an HR of 1.05 (95% CI: 0.84–1.29, p = 0.69), 1.04 (95% CI: 0.84–1.28, p = 0.72), and 1.14 (95% CI: 0.83–1.56, p = 0.43), none of which were significant.
This is a novel study to estimate mortality risk by timing of coffee consumption. Coffee consumers with morning preference had decreased all-cause and CVD-specific mortality risks; however, all-day type consumers had no significant association. It is not the amount of time, during which people consume coffee that matters but the time of the day, they use coffee.
Some of the possible associations include the influence of coffee on circadian disruption, melatonin disruption, and an increase in oxidative stress which contributes to CVD. Moreover, the suppression of inflammatory biomarkers was observed to be more effective when coffee was consumed in the morning with an association with increased inflammatory markers.
Coffee consumption could also have certain moderators, such as genetically inherited traits, or individuals’ lifestyles. However, the study has some inherent limitations: The analysis is based on observational data only where potential patients received a combination of treatments, and data collection depends on the patient’s recollection of the information.
In conclusion, it might be suggested that the timing of coffee intake has a stronger influence on health and mortality rate rather than the total amount of consumed coffee. The present research suggests that it is important to consider drinking habits when looking at the potential therapeutic effects of coffee consumption.
Regardless of coffee intake level, the timing of consumption matters in lowering the risk of death from all causes and mortality from CVD. Interestingly, there was a stronger association between early coffee use and a decreased risk of mortality than there was with later consumption of coffee. This emphasizes the significance of intake time when assessing how coffee consumption and health consequences are related.
References: Wang X, Ma H, Sun Q, Li J, Heianza Y et al., Coffee drinking timing and mortality in US adults. Eur Heart J. 2025; ehae871. doi:10.1093/eurheartj/ehae871
