A new analysis of three different studies totaling almost 300,000 people looked at the association between coffee consumption and mortality.(1) The researchers had data from 4,690,072 person-years, which can probably be characterized as “more than adequate”. The researchers found that coffee is associated with lower death rates.
Mortality rate by consumption for never-smokers was:
Significant inverse associations were found between coffee drinking and
This is not by any means the first study that has found such a relationship. For example, another one that looked at around 400,000 people found very similar hazard ratios and effect on diseases, but additionally reported effects on mortality due to respiratory diseases, infections, stroke, injuries and accidents, and diabetes; again, cancer deaths were not affected.(2)
What’s the mechanism of coffee’s effect on death? There are likely to be several.
Coffee promotes autophagy.(3) A higher level of autophagy, the cellular self-cleaning process that rids cells of junk proteins and structures, as well as infectious agents, is characteristic of youth and health. Therefore, coffee’s effects are similar in this regard to intermittent fasting or exercise.
Altogether, these results indicate that coffee triggers 2 phenomena that are also induced by nutrient depletion, namely a reduction of protein acetylation coupled to an increase in autophagy. We speculate that polyphenols contained in coffee promote health by stimulating autophagy.
…caffeinated coffee was positively related to insulin sensitivity and decaffeinated coffee was favourably related to measures of beta cell function. These results provide pathophysiological insight as to how coffee could impact the risk of type 2 diabetes mellitus.
Coffee lowers inflammatory markers.(5)
Coffee is an antidepressant.(6) Hazard ratio for depression in those consuming 4 or more cups daily was 0.80 compared to those consuming
Coffee prevents dementia and Alzheimer’s.(7) Drinking 3 to 5 cups a day was associated with a 65% decreased risk of dementia/Alzheimer’s in late life.
Lots of other studies could be cited, but you get the idea.
At least two possible components of coffee could explain these results: caffeine, and phytochemicals, the latter mainly polyphenols.
In many of these studies it was found that tea had little to no effect, and in my view caffeine may explain the difference. Coffee just has a lot more caffeine than tea, over twice as much typically, and many of these associations with coffee were seen at high doses.
As for the polyphenols, some of the associations were also seen with decaffeinated coffee. For instance, the study on coffee and autophagy found that decaffeinated coffee stimulated autophagy equally as well as caffeinated.
Coffee (and tea) polyphenols stimulate the Nrf2 transcription factor, which mobilizes the body’s antioxidant stress-defense mechanisms.(8) As such, coffee is an agent of hormesis, the process through which low doses of a toxic chemical produce healthful effects, and the process which is fundamental to health and long life.
So drink up. There appears to be little downside to coffee drinking. It doesn’t even increase the risk of something you might expect it to, atrial fibrillation.(10)