The Health Benefits Of Coffee: Do We Really Know Where They Come From?

Coffee is one of the most consumed drinks in the world. Many of us swear we need it simply to function normally, but coffee doesn’t just help you get through the morning. Every year, hundreds of academic articles concerning coffee are published, many of them investigating the benefits of coffee on human health. According to these studies, coffee drinkers experience a range of benefits including improved physical performance, cognitive function and even increased lifespan – people who drink 3-4 cups of coffee a day live about 15% longer than those who drink none. We discussed these benefits in more detail in this article.

While not all research fully agrees with all of these benefits, the weight of the evidence leans heavily in favour of coffee being beneficial for overall health. But why? Most sources will point to caffeine and to polyphenols, a family of plant-derived molecules with strong antioxidant properties. However, our understanding of exactly where the benefits of coffee come from is somewhat vague.

We know that caffeine is probably the most important component of coffee in terms of long-term health benefits, but we also know it’s not the only thing that matters. This information comes from animal studies of caffeine and from human studies comparing caffeinated coffee to decaffeinated coffee. For example, only caffeinated coffee seems to have a beneficial effect on cognitive function, but coffee seems to increase lifespan regardless of the presence of caffeine, though the effects may be weaker.

So where do these other benefits come from? This is where the science gets difficult to interpret. There are hundreds of active compounds in coffee besides caffeine, and most can be divided into one of four categories: 

• Polyphenols such as tannins. These are antioxidant, anti-inflammatory compounds that are perhaps most interesting for their effects on cognition and resistance to developing dementia.
• Non-caffeine alkaloids. These are less well studied compounds that may have similar benefits to polyphenols.
• Oils. Coffee contains oils that may affect cholesterol metabolism and may also have anti-cancer properties.
• Minerals and vitamins, such as vitamins B2, B3, and B5, manganese, potassium, and magnesium. 

Here’s the issue: the relative quantities of individual compounds can vary based on the variety of coffee bean, where they were grown, how long they were stored, and how the coffee is prepared. For example, filtering may remove some beneficial compounds. This means that studies looking at ‘coffee’ are technically looking at many similar but different drinks – rarely does a study impose restrictions on the exact type of coffee consumed. Even if they do, no two studies will be exactly the same. All this makes it nearly impossible to narrow down which compounds are truly important.

To make matters worse, the process of removing caffeine from coffee also removes other compounds, which means that studies comparing caffeinated and decaffeinated coffee don’t necessarily tell us what they appear to be telling us. If a study shows that caffeinated coffee has superior benefits, that might be partly because it contains more of these other beneficial compounds. Studying each compound in isolation is an option, but might overlook important synergistic effects when multiple compounds are combined together.

The take home message? Studying coffee is far from straightforward, and we still have a lot to learn about how coffee benefits our health. It could involve a complex interaction between caffeine and dozens of other compounds. While we don’t necessarily need to know exactly how coffee works in order to enjoy its benefits, such knowledge could be helpful for getting even more out of our daily dose. Hopefully further studies can tell us more about the most beneficial varieties and preparation methods.