Coffee is one of the most popular beverages worldwide. It is a brewed drink made from roasted coffee beans, and it contains caffeine and a range of other compounds that can have both positive and negative effects on human health.

In recent years, there has been considerable interest in the impact of coffee on the heart, with conflicting evidence and opinions on whether coffee is beneficial or harmful. This review of the literature aims to explore the effects of coffee on the heart and cardiovascular system.

Coffee and Cardiovascular Health

Cardiovascular disease (CVD) is the leading cause of death and disability worldwide, accounting for an estimated 17.9 million deaths in 2019. Studies have suggested that coffee consumption may be associated with a reduced risk of CVD and stroke.

A systematic review and meta-analysis of prospective studies found that moderate coffee consumption (3-5 cups/day) was associated with a significant reduction in CVD risk compared to no or low consumption (<1 cup/day).

Several mechanisms have been proposed to explain the potential cardiovascular benefits of coffee. These include antioxidant and anti-inflammatory properties, improved endothelial function, and reduced insulin resistance.

Coffee also contains bioactive compounds such as chlorogenic acid, which has been shown to have potential cardioprotective effects by reducing blood pressure and improving lipid metabolism.

Coffee and Blood Pressure

One of the concerns about coffee consumption is its potential impact on blood pressure, as hypertension is a major risk factor for CVD.

However, the evidence on this is mixed, with some studies suggesting that coffee may increase blood pressure, while others report no significant effect.

A meta-analysis of randomized controlled trials found that the acute effects of coffee on blood pressure were relatively modest, with an average increase of 3-4 mmHg in systolic blood pressure and 2-3 mmHg in diastolic blood pressure.

However, some individuals may be more sensitive to the effects of coffee on blood pressure, and chronic coffee consumption may have a more significant impact.

Coffee and Arrhythmias

An arrhythmia is an abnormal heart rhythm that can lead to palpitations, dizziness, and fainting.

Some studies have suggested that coffee consumption may increase the risk of arrhythmias, particularly in individuals who are already predisposed to these conditions.

A systematic review of observational studies found that moderate coffee consumption was not associated with an increased risk of arrhythmias.

However, there was some evidence to suggest that high coffee intake (>5 cups/day) may be associated with an increased risk of atrial fibrillation, a common type of arrhythmia.

Coffee and Cholesterol

Elevated cholesterol levels are a major risk factor for CVD, and there is some evidence to suggest that coffee consumption may have a beneficial effect on cholesterol metabolism.

A meta-analysis of randomized controlled trials found that coffee consumption was associated with a small but significant reduction in total cholesterol and LDL cholesterol levels.

The mechanism behind this effect is unclear, but it may be related to the antioxidant and anti-inflammatory properties of coffee.

Coffee and Heart Failure

Heart failure is a condition in which the heart is unable to pump enough blood to meet the body’s needs.

There is limited evidence on the impact of coffee consumption on heart failure, but some studies have suggested that moderate coffee consumption may have a protective effect.

A meta-analysis of prospective cohort studies found that moderate coffee consumption was associated with a 30% reduction in the risk of heart failure compared to no or low consumption.

However, this effect was not observed in individuals who consumed high levels of coffee (>5 cups/day).

Coffee and Mortality

There is some evidence to suggest that coffee consumption may be associated with a reduced risk of all-cause mortality, as well as mortality from CVD and stroke.

A meta-analysis of prospective studies found that moderate coffee consumption was associated with a significant reduction in all-cause mortality compared to no or low consumption.

However, this effect was not observed in individuals who consumed high levels of coffee (>5 cups/day).

Coffee and Exercise Performance

Caffeine is a well-known ergogenic aid that has been shown to enhance exercise performance. As coffee is a major source of caffeine, it is not surprising that coffee consumption has been studied in relation to exercise performance.

A meta-analysis of randomized controlled trials found that caffeine ingestion was associated with a significant improvement in endurance exercise performance, but not in short-term high-intensity exercise.

The optimal dose of caffeine was found to be 3-6 mg/kg body weight.

Coffee and Dehydration

Caffeine is a diuretic, which means that it can increase urine output and lead to dehydration. This has led to concerns about the potential impact of coffee consumption on hydration status.

However, a meta-analysis of randomized controlled trials found that coffee consumption did not have a significant impact on hydration status, and that moderate caffeine consumption (<400 mg/day) was not associated with dehydration or electrolyte imbalances.

Coffee and Sleep

Caffeine is a stimulant that can interfere with sleep quality and quantity. This has led to concerns about the potential impact of coffee consumption on sleep.

A meta-analysis of randomized controlled trials found that caffeine ingestion was associated with a significant reduction in sleep duration and quality, particularly when consumed close to bedtime.

However, the impact of coffee consumption on sleep may vary depending on individual sensitivity to caffeine and the timing and amount of consumption.