What would a morning look like without a strong Americano in hand? For many, waking up to their morning coffee is a happy habit as they take on a long and productive day with a stimulating kick-start with their cup of joe. Caffeine is the most widely used psychoactive substance in the world, and affects the same part of the brain as some hard drugs. Caffeine, however, affects a person in completely different ways. It combats that sluggish feeling we may have halfway through the day, acting as a stimulant that leaves a person feeling awake and energetic, seeming to increase alertness, thinking skills and our concentration.
However, aside from tasting delicious to those who enjoy a strong coffee, caffeine – in tea, coffee, and energy drinks – has many side effects on the body, especially the heart – some bad and, apparently, some good. The big question is: how much caffeine is too much on the heart? Is drinking tea and coffee bad for my heart? Can caffeine protect the heart?
To answer these questions, we need to understand how this vital organ reacts to regular caffeine intake.
Dr Ahmeda Ali, GP with webdoctor.ie, advises that caffeine stimulates heart-rate, acting as a stimulant by blocking a brain chemical called adenosine, which makes you feel tired. “By blocking adenosine, caffeine can increase the release of other chemicals like adrenaline, which raises heart rate slightly,” she says. “Studies show this effect is typically brief, and regular caffeine users tend to experience less of a heart-rate increase due to tolerance.”
A slight increase in blood pressure seems to accompany the consumption of large amounts of caffeine. “This effect is generally mild and tends to diminish with regular caffeine consumption, but it’s noticeable enough to affect people with high blood pressure or cardiovascular conditions,” says Dr Ali.
There is also a risk of irregular heartbeats at high doses. “Consuming very high amounts of caffeine, especially from energy drinks or excessive coffee, can trigger irregular heart rhythms in some people,” says Dr Ali. “This risk is generally higher in those sensitive to caffeine or with underlying heart conditions.”
Caffeine is quite active in having what seem to be adverse temporary effects on our heart after consuming a cup of coffee or the equivalent energy drink. However, there is a growing body of evidence that suggests caffeine may also be working behind the scenes to protect our heart. Dr Ali explains some studies in the past have shown that drinking coffee, tea or other caffeinated drinks might lower the risk of developing individual heart or metabolic diseases.
A recent study in The Journal of Clinical Endocrinology and Metabolism adheres to this. With a cohort of about 180,000 participants for caffeine analysis, this observational study highlighted that those who consumed a moderate amount of caffeine (200mg-300mg per day – about two cups of coffee), compared with non-consumers of caffeine (or less than 100mg per day), had a 40 per cent lower risk of developing multiple cardiometabolic disorders, which include conditions such as hypertension, stroke, diabetes or coronary heart disease. This lower risk increased to 48.1 per cent when three cups were consumed per day. With a large sample size, the study used multiple biomarkers to support the findings. Over time it appears caffeine consumption can play a role in ongoing heart health.
However, Dr Ali clarifies that it is still not fully clear if caffeine can help prevent having multiple cardiometabolic diseases at the same time or if they affect certain biological markers such as blood pressure or cholesterol related to these conditions. While the methodology of this study is valid and cohesive, and the results corroborate previous study findings, there are still questions to be answered about how strong the connection between caffeine and the heart is. There are limitations to the research that need to be addressed, as it does not take into account other factors that might determine the positive associations with improved heart health.
“This is what researchers are now trying to understand,” says Dr Ali as the findings of this most recent research attempts to indicate a potential protective effect for cardiovascular health irrespective of a person’s age, sex, physical activity, diet or whether or not they smoke. Dr Ali is conscious that cardiometabolic multimorbidity is becoming a bigger public health problem because it affects more and more people. As such the research is welcome and encourages further studies to validate the underlying relationship between caffeine and the heart.
When the science warns us about one element of caffeine intake having a negative effect on our hearts, but then also suggests multiple cups a day could be good for our hearts, how can coffee drinkers weigh up the risks alongside the benefits?
Research shows that a small level of caffeine intake shouldn’t be detrimental to a person’s heart health.
“Scientific research suggests that moderate caffeine intake – about two to four cups of coffee per day – may offer health benefits,” says Dr Ali, “including a reduced risk of heart disease and certain types of diabetes, largely due to its antioxidant and anti-inflammatory properties. However, high caffeine consumption can raise blood pressure and may cause heart-rhythm issues in some people, particularly those sensitive to caffeine or with pre-existing heart conditions.”
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Dr Ali suggests that for those who already enjoy caffeine in moderate amounts, continuing is probably safe and may be beneficial. But those with health concerns should consult a healthcare provider before increasing their intake.
“In short, caffeine, when consumed in moderation, may have benefits for heart health, though high doses can put stress on the heart, particularly for those with existing heart issues. Regular coffee or caffeine consumption, especially in moderate amounts, is linked to a lower risk of developing new cardiometabolic conditions.”
