New research into coffee confirms, and widens the scope of, its benefits.
Coffee is among the most commonly consumed beverages on earth.
Because of its popularity, it has attracted a great deal of research over the years.
After all, something that permeates society so thoroughly must be studied for its pros and cons.
Scientists have now stacked up a fair amount of evidence proving that coffee, when consumed in moderation, can protect against certain diseases and may even extend lifespan.
Gaps in our knowledge
But the findings to date leave some unanswered questions. For instance, "moderate consumption" — which usually means three to five cups per day — depending on the study, seems to be of benefit, but many people drink six or more cups each day.
So, do they still enjoy coffee's protective powers?
Also, certain people have genetic variations that alter the way in which they metabolize, or break down, caffeine. How are these individuals affected? Similarly, does the type of coffee — ground, instant, or decaffeinated — make a difference to health outcomes?
Other studies have attempted to answer the questions above, but, because fewer people fall into these categories, it has been difficult to make robust conclusions from the available data.
Recently, researchers at the National Cancer Institute (NCI) in Rockville and the National Institutes of Health (NIH) in Bethesda, both in Maryland, set out to get some answers.
Their work, which includes the data of more than half a million people in the United Kingdom, is published today in JAMA Internal Medicine.
Reopening the coffee question
The scientists found that, as predicted, coffee drinkers had a lower risk of death over the course of the follow-up. They also found that this reduction in risk extended to people who drank eight or more cups each day.
It also affected people who metabolize caffeine slower or faster than normal, and it worked across all coffee types (although the benefits were slightly less pronounced for instant coffee).
The fact that individuals who process caffeine differently and those who drink decaffeinated coffee also saw benefits hints that caffeine is not the main player in this beneficial relationship. Coffee consists of hundreds of different chemicals, making this a tricky code to crack.
One group of chemicals that scientists have been interested in is polyphenols, which are found in reduced levels in instant coffee. Much more work will be needed to understand how they fit into the bigger picture, though.
The new study is based on observational data, but because of the large number of participants used, the authors conclude:
"[T]hese results provide further evidence that coffee drinking can be part of a healthy diet and may provide reassurance to those who drink coffee and enjoy it."
With its unwavering popularity, research into coffee is guaranteed to continue. The authors hope that future studies focus more on how the preparation of coffee influences health outcomes.
For now, it seems firmly established that coffee has a raft of health benefits.