Coffee raises blood pressure briefly but is not linked to long-term hypertension risk in most people.
Coffee has been part of human life for more than 600 years, evolving from a regional drink into one of the most widely consumed beverages in the world.
Today, people drink close to two kilograms of coffee per person each year on average, often with strong preferences for specific beans, brewing styles, and preparation methods. How much someone consumes is partly shaped by genetics, particularly those that influence how the brain responds to rewards and how quickly the body processes caffeine.
Caffeine can cause a temporary rise in blood pressure, especially in people who do not drink coffee regularly or who already have elevated levels.
However, this short-term effect does not necessarily mean coffee needs to be avoided if you have high blood pressure or are concerned about cardiovascular health. Moderation is key.
So how exactly does coffee influence blood pressure, and how much is considered safe for those with higher readings?
Understanding what counts as high blood pressure
Blood pressure is the force blood exerts on artery walls when your heart pumps. It’s measured by two numbers:
- Systolic blood pressure, the higher of the two numbers, reflects the pressure created when the heart contracts and pushes blood through the arteries to the rest of the body.
- Diastolic blood pressure, the lower number, measures the pressure in the arteries when the heart relaxes and fills again with blood between beats.
Normal blood pressure is defined as systolic blood pressure of less than 120 millimeters of mercury (mm Hg) and diastolic blood pressure of less than 80 mm Hg.
Once your numbers consistently reach 140/90 or more, blood pressure is considered high. This is also called hypertension.
Knowing your blood pressure numbers is important because hypertension doesn’t have any symptoms. When it goes untreated, or isn’t well-controlled, your risk of heart attacks and strokes increases, and existing kidney and heart disease worsens.
About 31% of adults have hypertension with half unaware they have it. Of those taking medication for hypertension, about 47% don’t have it well-controlled.
How does coffee affect blood pressure?
Caffeine in coffee is a muscle stimulant that increases the heart rate in some people. This can potentially contribute to an irregular heartbeat, known as arrhythmia.
Caffeine also stimulates adrenal glands to release adrenaline. This makes your heart beat faster and your blood vessels to constrict, which increases blood pressure.
Blood caffeine levels peak between 30 minutes and two hours after a cup of coffee. Caffeine’s half-life is 3–6 hours, meaning blood levels will reduce by about half during this time.
The range is due to age (kids have smaller, less mature livers so can’t metabolize it as fast), genetics (people can be fast or slow metabolizers), and whether you usually drink it (regular consumers clear it faster).
The impact of caffeine on blood pressure from coffee (and cola, energy drinks, and chocolate) varies. Research reviews report increases in systolic blood pressure of 3–15 and a diastolic blood pressure increase of 4–13 after consumption.
The effect of caffeine also depends on a person’s usual blood pressure. An increase in blood pressure may be more risky if you have hypertension and existing heart or liver disease, so it’s best to discuss your coffee consumption with your doctor.
What else is in coffee?
Coffee contains hundreds of phytochemicals: compounds that contribute flavour, aroma, or influence health and disease.
Phytochemicals that directly affect blood pressure include melanoidins, which regulate the body’s fluid volume and activity of enzymes that help control blood pressure.
Quinic acid is another phytochemical shown to lower systolic and diastolic blood pressure by improving the lining of blood vessels, allowing them to better accommodate blood pressure rises.
Can coffee cause hypertension?
In a review of 13 studies that included 315,000 people, researchers examined associations between coffee intake and the risk of hypertension.
During study follow-up periods, 64,650 people developed hypertension, with the researchers concluding coffee drinking was not associated with an increased risk of developing the condition.
Even when they examined data by gender, amount of coffee, decaffeinated versus caffeinated, smoking, or years of follow-up, coffee was still not associated with an increased risk of developing hypertension.
The only exceptions suggesting lower risk were for five studies from the United States and seven low-quality studies, meaning those results should be interpreted with caution.
A separate Japanese study followed more than 18,000 adults aged 40–79 years for 18.9 years. This included about 1,800 people who had very high blood pressure (grade 2-3 hypertension), with systolic blood pressure of 160 or above or diastolic blood pressure of 100 or above.
Here, risk of dying from cardiovascular disease, including heart attack or stroke, was double among those drinking two or more cups of coffee a day compared to non-drinkers.
There were no associations with death from cardiovascular disease for those who had either normal blood pressure or mild (grade 1) hypertension (systolic blood pressure 140–159 or diastolic blood pressure 90–99).
The bottom line
There is no need to give up coffee. Here’s what to do instead:
- Understand your blood pressure levels, your medical history, and which foods and drinks contain caffeine so you can make informed choices.
- Take into account all factors that affect blood pressure and overall health, including family history, diet, salt intake, and physical activity, when deciding what you consume and how active you are.
- Pay attention to how your body responds to caffeine and avoid consuming it before having your blood pressure checked.
- Limit caffeine intake later in the day to prevent it from interfering with your sleep.
- Keep your coffee consumption moderate by limiting intake to four cups a day or opting for decaffeinated options.
- If your systolic blood pressure is 160 or higher or your diastolic blood pressure is 100 or higher, consider reducing intake to one cup per day and consult your doctor.
Adapted from an article originally published in The Conversation.
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1 Comment
Interesting article, however, acceptable BP surely depends on age, and one wouldn’t like someone at the age of > 70 to have such a low BP level that could cause a fall and either fracture a bone or have a head injury. And, also, studies have shown that people from the Middle East, especially women, have the lowest BP, and a BP of 135/65 could be regarded as hypertension.