Scientists Reveal the Surprising Truth About Coffee and Blood Pressure

Coffee may temporarily raise your blood pressure, but that doesn’t mean it’s secretly harming your heart. Researchers say that caffeine can briefly raise blood pressure by stimulating the heart and constricting blood vessels, especially in people who don’t drink coffee regularly. However, large studies involving hundreds of thousands of participants found no clear evidence that moderate coffee consumption increases the risk of high blood pressure. In fact, coffee also contains natural compounds that can help improve blood vessel function.

What is High Blood Pressure?

Coffee first entered people’s lives and bloodstreams over 600 years ago. Today, we consume an average of nearly two kilograms per person per year—often with very specific preferences regarding blends and brewing methods. How much you drink is influenced by genes that affect your brain’s reward system and caffeine metabolism. Coffee can raise your blood pressure in the short term, especially if you don’t usually drink it or already have high blood pressure. However, that doesn’t mean you have to give up coffee if you have high blood pressure or are concerned about your heart health. Moderation is key. So how does coffee affect your blood pressure? And if your blood pressure is high, how much can you drink?

Blood pressure is the force that blood exerts on the artery walls when your heart pumps. It is measured by two numbers: Normal blood pressure is defined as a systolic blood pressure of less than 120 millimeters of mercury (mm Hg) and a diastolic blood pressure of less than 80 mm Hg. Once your readings regularly reach 140/90 or higher, your blood pressure is considered high. This is also known as hypertension.

• The first and higher number is the systolic blood pressure, which is the force generated when your heart contracts and pumps blood into the body.
• The lower number, the diastolic blood pressure, is the force generated when your heart relaxes and refills with blood.

It is important to know your blood pressure readings, as high blood pressure does not show any symptoms. If left untreated or poorly controlled, your risk of heart attacks and strokes increases, and existing kidney and heart conditions worsen. About 31% of adults have high blood pressure, and half of them don’t know they have it. Among those taking medication for high blood pressure, about 47% do not have their blood pressure well controlled.

How Does Coffee Affect Blood Pressure?

The caffeine in coffee is a muscle stimulant that increases heart rate in some people. This may potentially contribute to an irregular heartbeat, known as arrhythmia. Caffeine also stimulates the adrenal glands to release adrenaline. This causes your heart to beat faster and your blood vessels to constrict, which raises blood pressure.

Blood caffeine levels peak between 30 minutes and two hours after drinking a cup of coffee. The half-life of caffeine is 3–6 hours, meaning that blood levels decrease by about half during this time. The range of variation depends on age (children have smaller, less mature livers and therefore cannot break down caffeine as quickly), genetics (people can be fast or slow metabolizers), and whether one consumes caffeine regularly (regular consumers break it down more quickly). The effects of caffeine from coffee (as well as cola, energy drinks, and chocolate) on blood pressure vary. Research reviews report an increase in systolic blood pressure of 3–15 mmHg and in diastolic blood pressure of 4–13 mmHg following consumption.

The effect of caffeine also depends on the individual’s usual blood pressure. An increase in blood pressure can be riskier if you suffer from high blood pressure and existing heart or liver conditions; therefore, it is best to discuss your coffee consumption with your doctor.

What Else is in Coffee?

Coffee contains far more than just caffeine—in fact, it contains several hundred bioactive phytochemicals that influence taste, aroma, and potential health effects. In addition to caffeine, chlorogenic acids, diterpenes such as cafestol and kahweol, melanoidins, and various organic acids and minerals play a key role.

Chlorogenic acids are considered particularly important antioxidant compounds in coffee. They can influence glucose and fat metabolism and are associated with potential effects on blood pressure and vascular function. During roasting, they are partially broken down, resulting in new compounds that may also be biologically active. Melanoidins are also formed during the roasting process through the so-called Maillard reaction, which is also responsible for the brown color and the typical roasted aroma. These substances possess antioxidant properties and could indirectly support vascular function, among other things through effects on inflammatory processes and vascular metabolism.

Diterpenes such as cafestol and kahweol are also present in coffee, particularly in unfiltered preparations like French press or espresso. They can influence cholesterol metabolism and are therefore a focus of nutritional research. Filter coffee contains significantly lower amounts of these substances. In addition, coffee contains small amounts of minerals such as potassium and magnesium, which also play a role in regulating blood pressure. Overall, coffee is thus a complex beverage with a wide variety of bioactive compounds, the effects of which depend on the method of preparation and the individual’s physiological response.

Can Coffee Cause high Blood Pressure?

In a review of 13 studies involving a total of 315,000 participants, researchers investigated the association between coffee consumption and the risk of high blood pressure. During the study’s follow-up period, 64,650 people developed high blood pressure, though the researchers concluded that coffee consumption was not associated with an increased risk of developing this condition. Even when the data was broken down by gender, coffee consumption, decaffeinated versus caffeinated coffee, smoking, or follow-up duration, no association was found between coffee consumption and an increased risk of high blood pressure.

The only exceptions suggesting a lower risk were five studies from the United States and seven low-quality studies, meaning these results should be interpreted with caution. A separate Japanese study followed more than 18,000 adults aged 40–79 over a period of 18.9 years. This included about 1,800 people with very high blood pressure (stage 2–3 hypertension), i.e., a systolic blood pressure of 160 or higher or a diastolic blood pressure of 100 or higher.

Here, the risk of dying from a cardiovascular disease such as a heart attack or stroke was twice as high among those who drank two or more cups of coffee daily compared to non-drinkers. Among individuals with normal blood pressure or mild hypertension (stage 1) (systolic blood pressure 140–159 or diastolic blood pressure 90–99), there was no association with death from cardiovascular disease.

The Bottom Line

There is no reason to give up coffee, as numerous studies show that moderate consumption is not associated with an increased risk of high blood pressure in most healthy people and can even be part of an overall balanced lifestyle. Here’s what you should do instead:

• • Know your blood pressure, your medical history, and which foods and beverages contain caffeine
  • Consider all factors that influence your blood pressure and health—family history, diet, salt intake, and physical activity—so you can make informed decisions about what you consume and how much you exercise
  • Pay attention to how caffeine affects you and avoid it before having your blood pressure checked
  • Avoid caffeine in the afternoon so it doesn’t interfere with your sleep
  • Try to moderate your coffee consumption by drinking four cups or fewer per day or switching to decaffeinated coffee
  • If you have a systolic blood pressure of 160 or higher or a diastolic blood pressure of 100 or higher, you should consider limiting your intake to one cup per day and talk to your doctor.