Imagine yourself walking down a street in a French town. You spot a picturesque café in the square, perhaps one that had been painted by Van Gogh. People are in the café, relaxed, sipping their coffees. It looks so inviting. You want to join them and order a nice café Americano, but you wonder how good is coffee for the heart?
Before we drip into the medical data, some fun facts about coffee. Coffee grows on a bush and the beans are actually the pit of a berry, which makes coffee a fruit. Coffee has been consumed for about 500 years. In the US, about 85% of adults drink coffee daily, averaging 1.5 standard cups per day. Brazil is the largest exporter of coffee in the world and Finland is the worldwide leader in coffee consumption.Now let’s pour over the physiological effects of coffee. Coffee is not just caffeine; the beans have over 100 active substances which have a variety of metabolic effects. Drinking coffee causes the heart rate and blood pressure to increase. Effective sleep may be suppressed. Caffeine increases catecholamines (adrenaline). Coffee stimulates the electrical system of the heart. For these reasons, many cardiologists recommend decreasing or stopping caffeine use. Is that recommendation justified?
Does coffee cause heart arrhythmias?
Doctors have always felt that coffee may increase the number of premature atrial contractions (PACS) and premature ventricular contractions (PVCs). Increased PACS may result in atrial fibrillation (Afib) while increased PVCS may cause ventricular arrhythmias. A recent study in healthy volunteers showed that coffee did not increase the number of daily PACs, but may increase PVCs. The accumulated medical literature has shown that coffee drinkers have a lower risk for Afib than those who do not drink coffee. Drinking one cup per day lowers the risk for Afib by 20%. The reason for this may be that long-term coffee drinkers develop a tolerance to the electrical stimulating effects of caffeine. However, there is a lot of individual variation in terms of response to coffee. Approximately 25% of patients report coffee as a trigger for Afib. Clearly those patients should avoid it. Similarly, the literature does not show an increase in ventricular arrhythmias with coffee consumption, despite a possible increase in PVCs. This holds true even for patients with history of significant ventricular arrhythmias. It appears that drinking coffee is safe for most patients in terms of their potential for arrhythmia.
Is it the caffeine?
Coffee is the most commonly used stimulant in the world. Coffee activates the central nervous system, boosts alertness and has a variety of psychoactive effects. Are these effects due solely to caffeine? In an interesting study people were given coffee or plain caffeine in water and then underwent MRI scans of the brain. The coffee drinkers had a heightened state of preparedness, were more responsive and had higher executive brain functioning than the plain caffeine group. It appears there is more to coffee than just caffeine.
Does coffee raise blood pressure?
The effect of coffee on blood pressure is still not decided. Drinking a cup of coffee will transiently increase blood pressure for about 30 minutes. Coffee stimulates catecholamines and stimulates receptors in the blood vessels to constrict, causing an increase in blood pressure. However, this is counterbalanced by an increase in nitric oxide, which dilates blood vessels. Over time, the acute effect of a blood pressure bump with each cup is blunted in regular coffee drinkers. In fact, regular consumption of coffee is associated with lower overall blood pressure readings compared to nondrinkers. It appears that coffee doesn’t cause hypertension.
What are the other metabolic effects of coffee?
Coffee has both good and bad effects. Regular coffee drinking lowers body fat and reduces the risk for obesity. In addition, coffee lowers the risk for type 2 diabetes. On the other hand, coffee may increase cholesterol levels. The effect depends on the type of coffee, the degree of roasting and the type of brewing. Boiled, unfiltered coffee (such as Turkish or Greek coffee, made by boiling water with coffee grounds in a pot) raises cholesterol more than filtered coffee. Other nonfiltered coffees, such as espresso, are significantly associated with raised serum cholesterol levels. Filtered coffee can raise cholesterol but not as significantly as unfiltered coffee. There is no increase in cholesterol with instant coffee. It appears that drinking filtered coffee is the safer than alternatives.
Does coffee reduce the risk for cardiac events?
In the literature, coffee drinkers have consistently had a lower risk for heart problems and death. A study from Europe in 2017 showed that drinking 2 to 4 cups of coffee per day reduced the risk of dying by 15%, reduced the risk of cardiac death by 17% and reduced the risk of dying from cancer by 4%. A more recent study confirms and expands these findings. The study followed 500,000 people for 10 years. In people without known heart disease, drinking 2 to 3 cups of coffee per day lowered the risk for heart artery disease, heart failure, stroke and dying from any cause. People withheart disease also showed improved survival and no increased risk for arrhythmias. The relationship held regardless of instant versus ground coffee, or decaf versus caffeinated coffee. The reason for these favorable benefits may be coffee’s metabolic effects (lower risk for obesity and diabetes), as well as coffee’s anti-inflammatory and anti-oxidant properties. In addition, coffee drinkers consistently do more physical activity than nondrinkers. It seems that 2 to 3 cups of coffee per day is the sweet spot, a level of consumption where coffee is not only safe, it may be cardioprotective.
It can be concluded that coffee is not associated with high blood pressure, significantly elevated blood cholesterol (if the coffee is filtered) or dangerous arrhythmia. It is associated with a lower risk for obesity, type 2 diabetes, heart artery disease, stroke and death. So find yourself a nice little café. Order one or two cups of (filtered) coffee. Then sit and watch the world go by, guilt free.
