As a beverage, coffee has been popular for a long time, with the discovery of the stimulant effect of the plant in Ethiopia early in the 14th century or thereabout, its cultivation in the 15th century in the Arabian Peninsula, from where it spread throughout Europe in the 16th and 17th centuries1.
My parents were tea-drinkers, so I didn’t start drinking coffee until I was in my very late teens, but by the time I was at university doing my higher degree it had escalated to as many as 12 cups a day. However, that quickly moderated down to 4 cups a day, something that has been almost constant for a few decades, except for a short interval where I went ‘cold turkey’ and switched to tea. That didn’t last and I soon came back to coffee. I have often wondered how it affects me beyond waking up my brain and heart every morning. So, I started looking around for published statistical studies which may show if there are any deleterious or beneficial effects
There are many such published papers which look at a collection of individuals and track them through time and compare the results with a control group of individuals which have not been exposed to the factor being studied. This, for want of a better term is called an analysis. A paper which extracts data from a series of such analytical papers and uses that data to come to a conclusion is called a meta-analysis. However, in my search for something on the effect of coffee, I bumped into what is termed an ‘umbrella review’, something I had never encountered before. It seems that is mostly used in such fields as medicine. An umbrella review compiles evidence from multiple existing meta-analyses and allows easy comparison between other individual reviews. It is considered to be high in the hierarchy of evidence2.
The rise in lifestyle-related diseases such as cardiovascular disease, diabetes, stroke, dementia, has motivated studies of various lifestyle factors to determine the relationships between those and the various diseases. One of the factors studied fairly regularly is coffee consumption. Some studies show coffee consumers are at risk for such diseases, whereas other studies show its active components protect them. A comprehensive umbrella study has been undertaken which includes the results of 10 years of investigations up to October 2023 and excluded case reports and non-English observational research. This umbrella review includes 11 meta analyses combining the results from over 450,000 published papers which studied almost 12 million individuals. This study found that drinking up to four cups of coffee a day reduced the risk of stroke by 12% compared with not drinking any coffee. Coffee drinkers also had a 10% reduced risk of developing dementia. However, coffee drinkers had a 19% increased risk of developing cardiovascular diseases compared to non coffee drinkers. In this study, it was suggested that heavy coffee drinkers were more at risk of cardiovascular disease than those who drank less3.
So, I’ll stick with my 4 cups per day routine; otherwise, I’d be bleary-eyed until midday.
Sources
I would consider four cups a day in the high range, but then I have a large cup, from which I drink one coffee a day. It’s something like 2.5 shots. Is there a standard measure for a “cup of coffee”? Is there a standard for a “shot”?