How much coffee can you drink without harming your heart: the cardiologists’ answer

This is roughly three to five small cups of ordinary coffee, each holding about 240 ml. However, this conversion is rather approximate: a large or particularly strong serving from a coffee shop may contain as much caffeine as several cups made at home.

The 400 mg guideline is not suitable for everyone and is not a recommended target. Caffeine can cause palpitations, temporarily raise blood pressure, increase anxiety and disrupt sleep. The reaction depends on age, genetics, medication and general health.

Details

The American Heart Association has issued a scientific statement on the effects of caffeine on blood pressure, cholesterol, heart rhythm, and the risk of stroke, heart failure and other conditions.

This is not a new clinical trial, but a review of previously published studies. Experts have concluded that moderate consumption of caffeinated coffee does not generally increase cardiovascular risk in most adults.

Some observational studies even link two to four cups of coffee a day with a lower incidence of stroke, coronary heart disease, heart failure and type 2 diabetes. However, this does not prove that it is coffee specifically that prevents these conditions.

People who drink coffee in moderation may differ from others in terms of diet, physical activity, income, smoking habits and general health. Furthermore, any potential beneficial effect may be linked not to caffeine, but to other substances contained in coffee.

For this reason, cardiologists do not recommend starting to drink coffee or increasing your intake for the sake of protecting your heart.

How many cups equal 400 mg

In a standard cup of brewed coffee, the caffeine content can range from approximately 9.4 to 20.6 mg per 30 ml. A 240 ml cup may therefore contain between 75 and 165 mg.

It follows that 400 mg does not always equate to five cups. Depending on the variety, strength and method of preparation, the daily limit can be reached with just two or three large servings.

It is particularly difficult to estimate the caffeine content of coffee from a café. The cup size can be as large as 350–500 ml, and the drink sometimes contains several shots of espresso. Cold brew coffee, which has been steeped for a long time, can also be very strong.

Caffeine isn’t just found in coffee. It’s also present in tea, chocolate, cola, energy drinks, some sports supplements, painkillers and other medicines. When calculating your daily intake, you need to take all these sources into account.

How coffee affects blood pressure

Blood pressure may rise temporarily after consuming caffeine. The effect is usually more noticeable in people who rarely drink coffee or who are particularly sensitive to stimulants.

With regular consumption, some people develop a tolerance, so the reaction becomes less pronounced. This may explain why a short-term rise in blood pressure after a cup of coffee does not necessarily lead to the development of chronic hypertension.

However, large doses of caffeine can significantly raise blood pressure, especially if it is already high. Therefore, there is no one-size-fits-all rule here: people with hypertension should discuss their coffee intake with their doctor.

Caffeine can also skew the result before a blood pressure reading. It is usually recommended to avoid consuming it for at least 30 minutes before the test.

Does coffee cause arrhythmia?

The common belief that any cup of coffee triggers heart rhythm disturbances is not supported by current evidence. Moderate consumption is not usually associated with an increased risk of atrial fibrillation — one of the most common types of arrhythmia.

In some randomised studies, coffee has even been linked to fewer episodes of atrial fibrillation. However, at the same time, some participants experienced more frequent premature ventricular contractions — extra heartbeats that may feel like skipped beats or the heart stopping.

Thus, the response depends on the type of arrhythmia and the individual’s specific characteristics. If you regularly experience pronounced palpitations, dizziness or discomfort after drinking coffee, you should not increase your intake based on average guidelines.

The method of preparation matters

It is not only caffeine that can affect heart health. Coffee beans contain cafestol — a substance capable of raising levels of low-density lipoproteins, known as ‘bad’ cholesterol.

More cafestol remains in unfiltered coffee: that brewed in a French press, a Turkish coffee pot or by boiling. It is also present in espresso, although the final amount depends on the serving size.

A paper filter traps most of the cafestol. Therefore, filtered coffee generally has less of an effect on cholesterol levels.

Syrups, sugar, whipped cream and other additives can turn coffee into a high-calorie treat. This does not mean that a small amount of milk automatically makes the drink unhealthy, but the composition of the whole serving should also be taken into account.

Why energy drinks raise more concerns

Coffee and energy drinks cannot be considered equivalent sources of caffeine. Energy shots may contain three to four times more caffeine per unit volume than regular coffee.

They are often consumed quickly, so a high dose enters the body within a short space of time. As well as caffeine, they may contain sugar and other stimulants, the combined effects of which are less well understood.

High doses of energy drinks have been linked to a sharp rise in blood pressure and heart rhythm disturbances, including in young people with no diagnosed heart conditions. Therefore, the conclusion regarding the safety of moderate coffee consumption cannot be applied to concentrated energy drinks.

Who the general guidelines may not apply to

The rate at which caffeine is metabolised depends on genetics, age, metabolism, habitual consumption and any medication being taken. For one person, several cups may cause no noticeable effects, whilst for another, a single serving may lead to tremors, anxiety or insomnia.

A more cautious approach is required for people with certain cardiovascular conditions, uncontrolled blood pressure, severe sleep disorders or high sensitivity to caffeine. Stricter limits apply to pregnant women, and the 400 mg guideline for adults is not intended for children or adolescents.

This is general information, not personalised medical advice. If you have a cardiovascular condition or are taking medication, it is best to consult your doctor to determine a safe amount of caffeine.

Why this is important

Coffee is the main, but not the only, source of caffeine. Trying to count only cups of coffee can lead to inadvertently exceeding the recommended intake, especially if a person is also drinking tea, cola or energy drinks and taking caffeine-containing medicines.

The new guidance helps to distinguish between moderate consumption of regular coffee and concentrated doses of stimulants. For most adults, a few cups of coffee do not pose a risk to the heart, but more is not necessarily better.

The link between moderate coffee consumption and a reduced risk of certain diseases should also not be taken as proven evidence of a health benefit. Observational studies do not yet allow us to determine whether it is the drink itself that protects the heart or whether the result is due to other lifestyle factors.

Background

Caffeine blocks the action of adenosine — a substance that helps the body slow down and feel tired. This is why people usually feel more alert after drinking coffee, and their heart rate and blood pressure may change temporarily.

In most people, the maximum concentration of caffeine in the blood is reached within about an hour. The substance is then gradually metabolised by the liver, although the rate of this process varies considerably.

As well as caffeine, coffee contains hundreds of other compounds. Some of these have antioxidant and anti-inflammatory properties. Because of this, it is difficult to separate the effects of pure caffeine from those of the drink as a whole.

Most long-term studies are also based on participants’ self-reports of the amount of coffee they have consumed. The actual caffeine content in each serving is not usually measured, which further limits the accuracy of the findings.

Source

The scientific statement by Gregory Marcus and a group of experts from the American Heart Association , *Caffeine and Cardiovascular Disease: A Scientific Statement From the American Heart Association*, was published in the journal *Circulation* in 2026.