In moderation, drinking coffee tends to improve health, not harm it. Large-scale analyzes of the damages or benefits of a cup of coffee have shown almost all its aspects as positive or, at least, neutral.
Another recent study, conducted in more than half a million inhabitants of the United Kingdom, confirms it again.
The researchers wanted to examine how coffee habits affected overall health, as measured by a statistic called all-cause mortality. That basically means that they grouped people by the amount of cups of coffee they drank per day, and then examined whether the groups that consumed more cups had more deaths during the study.
If the cohort that drank eight cups per day had fewer deaths than the group that drank only two, that would imply that somehow high volume coffee drinkers were healthier. And that is exactly what they found.
In 502,641 participants who were between 38 and 73 years old, both men and women, the more coffee a person drank, less likely to die.
Just a correlation but something else
The differences were not large, but they were statistically significant. However, it should be noted that these kinds of studies are observational: nobody is assigning groups of participants to drink five or two or zero cups per day and then make sure that their lives are identical, so they cannot provide any real causality. They are just correlations.
Drinking coffee can be associated with many other habits that influence health, or perhaps not drinking coffee is associated with something we ignore. For example, people who have serious diseases like cancer cannot drink coffee, but these people are also more likely to die, which would artificially increase the mortality of the group that did not drink coffee.
However, this study went a little further than similar ones and examined the genetic variations in caffeine metabolism. There are certain mutations that make a person respond to caffeine in different ways. Researchers believe that this may partly explain why some people can take a cappuccino after dinner and sleep well, while others are unable. In the present study, a large database containing genetic information about the participants was used to assess whether certain variants correlated with better or worse health outcomes. But even examining 400,000 people for whom genetic data were available, the researchers found no difference in results between those whose genes predisposed them to caffeine sensitivity and those who did not. That is, through genetic variants, those who drank more coffee tended to have a lower risk of death.
Caffeine, in fact, is the least important thing to take advantage of the supposed benefits of coffee: the caffeine content did not change the risk of death. Even instant coffee seems to work. Researchers aren't sure what's in coffee that seems to improve our health, but there is increasing evidence that this component is not caffeine.