How many times have you had a cup of coffee and felt none of that energy boost everyone talks about? How often have you heard a coworker say they can’t function until they’ve had their morning coffee? Or how many times has your mother told you that drinking too much coffee is bad for you?
There’s no doubt that there is a lot of confusion and significant individual variability in how caffeine affects our bodies. Keep reading, because in today’s article we’ll clear up some of these doubts and explain the reasons behind these differences.
Before we go any further, we need to understand the substance we’re talking about: caffeine. Caffeine is a naturally occurring chemical compound found in plant-based sources such as coffee beans, cocoa, tea leaves, guaraná berries, and kola nuts. It is commonly consumed for its stimulating effect on the central nervous system and, in moderate doses, increases alertness and reduces drowsiness. This is why it is one of the most widely consumed substances worldwide.
When we think of caffeine, coffee is usually the first thing that comes to mind. However, it’s important to note that coffee is not the only source of caffeine. The European Food Safety Authority (EFSA) has ranked common caffeine-containing products from highest to lowest:
- 1 cup of filtered coffee (200 ml)
- 1 standard-sized energy drink (250 ml)
- 1 espresso (60 ml)
- 1 cup of tea (220 ml)
- 1 regular cola drink (355 ml)
- 1 bar of dark chocolate (50 g)
- 1 bar of milk chocolate (50 g)
For many years, there has been significant debate about the effects of caffeine on our health. As mentioned earlier, some beliefs—supported by scientific evidence—suggest that caffeine may worsen or negatively affect cardiovascular health. At the same time, other studies with equally strong evidence point to a cardioprotective effect. This discrepancy exists because the exact mechanisms through which caffeine influences the cardiovascular system are still not fully understood.
After taking a deeper look at the research, one of the most important factors explaining these differing conclusions is individual genetics—specifically, caffeine metabolism and susceptibility to anxiety or sleep disturbances triggered by caffeine intake.
Approximately 95% of the caffeine we consume is metabolized in the liver by the cytochrome P450 system, more specifically by the CYP1A2 enzyme. The activity of this enzyme determines how quickly caffeine is broken down and eliminated, and therefore how fast we feel its stimulating effects. Based on this, people generally fall into two groups: fast metabolizers and slow metabolizers of caffeine.
Fast metabolizers experience the energy boost quickly and eliminate caffeine faster, meaning it remains in their system for a shorter period of time. Slow metabolizers, on the other hand, may take longer to feel the stimulating effects—or may not notice them at all—while caffeine stays in their body much longer. In these individuals, high caffeine intake may have a greater impact on cardiovascular health.
We also need to remember that caffeine’s effects are not determined solely by how it is metabolized. Caffeine can also bind to other receptors, such as ADORA2A. Variations in this receptor may increase the likelihood of anxiety and sleep disturbances after caffeine consumption, which can also indirectly affect cardiovascular health.
Another factor influencing how caffeine affects us is tolerance. Caffeine tolerance develops over time. If you used to feel an energy boost but no longer do, taking a break from caffeine for a period of time may help reduce tolerance so that you can experience its stimulating effects again when you resume consumption.
After this review, we can conclude that there is no absolute truth when it comes to caffeine consumption and cardiovascular harm or benefit. The response goes far beyond a simple yes or no. Understanding your genetic profile—particularly how you metabolize caffeine and your susceptibility to anxiety and sleep disturbances—can help determine whether caffeine has a negative effect on you personally.
