Longevity Briefs: The Health Benefits Of Coffee Depend On When You Drink It

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

The problem:

There are many studies showing that coffee is associated with various health benefits including improved physical and cognitive performance, as well as reduced mortality rates. Studies comparing caffeinated and decaffeinated coffee tell us that caffeine is probably the main contributor to these benefits, though coffee also contains many beneficial antioxidants, oils and minerals. However, caffeine can negatively impact sleep, and we know that poor sleep quality and quantity is associated with increased mortality. After someone consumes caffeine, it takes around 5 hours to clear half of that caffeine from the blood, so it is thought to be best to get your caffeine fix earlier on during the day. This study investigates whether drinking coffee later in the day has a measurable impact on its benefits.

In the study, researchers examined data from 40,725 participants of the National Health and Nutrition Examination Survey (NHANES), a long-term study in the US in which health and lifestyle information is collected. They categorised participants into three groups based on their self-reported coffee consumption patterns: morning-type drinkers who drank most of their coffee before 12am and barely consumed any later in the day; all-day-type drinkers whose coffee consumption was spread throughout the entire day; and non-drinkers.

The discovery:

After a median follow-up of 9.8 years, and after controlling for confounding factors like consumption of other caffeinated drinks, the morning drinkers were 12% less likely to have died from all causes when compared to the non-drinkers. When it came to the all-day drinkers, on the other hand, there was no statistically significant difference in mortality rates between them and the non-drinkers. This remained true when looking at cardiovascular disease specifically: the morning-type pattern was associated with a 31% reduction in mortality, while the all-day pattern was not. Coffee consumption did not significantly affect cancer risk regardless of consumption timing.

These relationships also remained true regardless of how many cups of coffee the participants consumed. Whether they drank one cup a day or more than three cups, morning-type drinkers saw a statistically significant mortality reduction while all-day-types did not.

The implications:

The health benefits of coffee appear to fade away in people who consume coffee throughout the whole day, which in this study was 16% of the participants. The most obvious explanation for this is that consuming caffeinated drinks later in the day impedes sleep, which is enough to cancel out the benefits of caffeine and the other compounds within the coffee. The researchers also propose an additional explanation, which is that the anti-inflammatory compounds within coffee do more good if consumed earlier in the day, since some inflammatory molecules spike in the morning and then decline throughout the day. 

Since this study was observational in nature, we can’t be certain that timing of coffee consumption was the only reason the all-day-type drinkers didn’t receive the health benefits. It is likely that at least some people who only drink coffee in the morning do so because they are more health-conscious and therefore more likely to be healthy in other ways that are hard to completely control for. It’s also possible that people with poor sleep quality need to drink coffee later to make it through the day. Until we have more research, though, concentrating your coffee consumption earlier in the day seems like a safe bet. It may also be worth avoiding caffeine consumption for one hour after waking, as some research suggests this can also interfere with the sleep cycle.