Is Too Much Caffeine Putting Your Heart at Risk?

Key Takeaways

• In a recent study, healthy people who consumed 400 milligrams (mg) or more of caffeine per day had an elevated heart rate and blood pressure after a 3-minute step test, even after a rest period - which signals a risk of heart disease.
• This amount of caffeine is equal to about four cups of coffee or Red Bull, or 10 cans of Coca-Cola.
• At-risk groups like older adults and pregnant people should be especially careful about their caffeine intake.

Healthy adults who drink more than 400 mg of caffeine per day on most days of the week may be more likely to develop heart disease , a new study found.

That amount of caffeine roughly translates to about four cups of coffee (or one Venti Pike's Roast from Starbucks), 10 cans of Coke, or four Red Bulls.

Regular consumption of a large amount of caffeine can stimulate your heart, leading to increased heart rate and elevated blood pressure, and that can cause many other heart problems as you get older, says the lead study author, Nency Kagathara, MBBS, a researcher in the department of internal medicine at the Zydus Medical College and Hospital in Dahod, India.

Dr. Kagathara presented the new findings at the American College of Cardiology Asia 2024 conference in Delhi, India.

How Does Caffeine Impact Heart Rate Recovery and Blood Pressure?

Caffeine affects metabolism by stimulating the nervous system, releasing free fatty acids from fatty tissue, and increasing urination. Most studies on caffeine and heart health suggest that 400 mg per day or less is safe for healthy adults.

Investigators designed the study to better understand how consuming a lot of caffeine on a regular basis impacted the hearts of younger adults, specifically the recovery of heart rate and blood pressure.

A total of 92 randomly selected participants between 18 and 45 years old with normal blood pressure completed the study.

Chronic caffeine consumption was defined as the intake of caffeinated drinks such as tea, coffee, Coke, Pepsi, coffee, and Red Bull for five days per week for more than one year.

People were asked to undergo a three-minute step test, followed by measurements of blood pressure and heart rate at both one minute and five minutes after the exercise.

About one-fifth of the group (18 people in total), reported drinking more than 400 mg of caffeine a day, which appeared to hinder their heart recovery and elevate their blood pressure after the step test.

The subgroup of people who consumed over 600 mg of caffeine daily were the most likely to have an elevated heart rate over 100 beats per minute and blood pressure greater than 140/90 millimeters of mercury (mmHg) after five minutes of rest following the test.

High Amounts of Caffeine Could Increase Heart Disease Risk Down the Road

This study adds to our understanding that high doses of caffeine, particularly above 600 mg per day, may increase cardiovascular risk even in young, healthy people, possibly due to its impact on the autonomic nervous system, says Surabhi Atreja, MD , an interventional cardiologist and health sciences clinical professor at UC Davis Health in California.

The autonomic nervous system is composed of the sympathetic system, sometimes called the "fight or flight" response; the parasympathetic system, or "rest and digest"; and the enteric system, which controls the GI tract, pancreas, and gallbladder. Together, they regulate important body functions such as heart rate, blood pressure, breathing, digestion, and sexual arousal.

Because of its effects on the autonomic nervous system, regular intake of high levels of caffeine could put otherwise healthy individuals at risk of high blood pressure and other cardiovascular events as they get older, says Kagathara.

To prevent this, even healthy people who are getting more than 400 mg per day of caffeine should decrease or limit their consumption, she says.

"Increasing awareness of these risks is vital to improve heart health for all," she adds.

The Study Has Some Limitations

Right now, the study has only been presented with the abstract (and not yet published as a full study in a peer-reviewed journal), and so detailed information about the number of patients they found to be in this subgroup who drank more than 600 mg of caffeine isn't included, says Dr. Atreja, who was not involved in the study.

"It's also a small study with very few patients, with high chronic consumption of caffeine being studied with no control group," she adds.

It's also possible that the participants with high caffeine intake had other characteristics that may explain the high blood pressure, since high caffeine consumption is often associated with lifestyle habits such as smoking, a lack of physical activity, or an unhealthy diet, says Rob van Dam, PhD , a professor at the Milken Institute School of Public Health at George Washington University in Washington, DC. Dr. van Dam was not involved in this research but has published research on caffeine's impact on health.

Because of what's missing from this study, it's hard to draw many conclusions, he says.

What Is the Recommended Limit for Caffeine Intake?

"Based on a larger body of research evidence, it is generally recommended to keep caffeine intake to a maximum of 400 mg per day, which also applies to the general population without specific cardiovascular health conditions," he says.

In a 2020 review published in the New England Journal of Medicine , van Dam and his coauthors concluded that adults should limit their intake to 400 mg per day, and for people who are pregnant or breastfeeding, 200 mg per day.

Both van Dam and Atreja agree that these guidelines are not "one-size fits all."

"Individual tolerance to caffeine can vary, and some people may experience side effects such as jitteriness, anxiety, or sleep disturbances, even at lower doses," says Atreja.

It is worth noting that people with preexisting conditions, such as high blood pressure, arrhythmia, and premature ventricular beats, as well as people who are over 65 or pregnant, should be more careful with even smaller amounts of caffeine, she says.

High Doses of Caffeine Could Increase the Risk of High Blood Pressure and Heart Problems in Older Adults

Although the study findings are preliminary, they suggest that regular consumption of higher doses of caffeine can affect the autonomic nervous system and create cardiovascular risk even in healthy subjects, says Atreja.

"This study does not directly address this question for patients with cardiovascular risk factors or diseases. However, many other studies have shown that patients who are elderly and have cardiovascular risk may be susceptible to more cardiovascular events like hypertension [high blood pressure] and arrhythmia at even 400 mg or less," she says.

Editorial Sources and Fact-Checking

Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy . We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.

Sources

1. New Study Finds Chronic High Caffeine Consumption May Heighten Risk for Cardiovascular Disease. American College of Cardiology . August 15, 2024.
2. Caffeine Chart. Center for Science in the Public Interest . July 2023.
3. Spilling the Beans: How Much Caffeine Is Too Much? U.S. Food and Drug Administration .
4. Waxenbaum JA et al. Anatomy, Autonomic Nervous System. StatPearls . July 24, 2023.
5. van Dam RM et al. Coffee, Caffeine, and Health. New England Journal of Medicine . July 22, 2020.

Meet Our Experts See Our Editorial Policy Meet Our Health Expert Network

Becky Upham

Author

Becky Upham has been professionally involved in health and wellness for almost 20 years. She's been a race director, a recruiter for Team in Training for the Leukemia & Lymphoma Society, a salesperson for a major pharmaceutical company, a blogger for Moogfest, a communications manager for Mission Health, a fitness instructor, and a health coach.

She majored in English at the University of North Carolina and has a master's in English writing from Hollins University.

Upham enjoys teaching cycling classes, running, reading fiction, and making playlists.

See full bio See Our Editorial Policy Meet Our Health Expert Network