Studies on caffeine's effects on heart health have gained interest in recent years. One crucial question remains: How much caffeine is too much?In this roundup of the latest studies exploring the effects of caffeine on cardiovascular health, Medical News Today compiles the most recent evidence to highlight key findings and takeaways.Some studies suggest that consuming caffeine may help boost vascular health and lower the risk of type 2 diabetes, while others indicate that consuming too much may increase the risk of stroke. Millions of people are regular coffee drinkers . Some people prefer to consume the popular caffeinated beverage in the morning to increase alertness and alleviate fatigue, while others consume it throughout the day for multiple other health benefits .
Considering that around 1 in 7 deaths worldwide are caused by coronary heart disease , coffee's potential cardioprotective benefits make it an exciting topic of research.
The most recent study on this topic, published in Rheumatology on October 9, found that consuming more caffeine—found in sources such as coffee, tea, and cocoa—may help improve blood vessel health. What made this study particularly interesting was that it was conducted in patients with lupus , an autoimmune disease that has been tied to an increased risk of stroke, heart attack , and cardiovascular disease.
But what does all the evidence so far say? Can coffee improve heart health , or does too much cause harm?
Building upon Medical News Today's regular in-depth reporting on studies related to heart health, this overview aims to provide a snapshot of the key pieces of research on caffeine 's effects on the heart and overall health with experts' views on these findings.
In a nutshell:
According to a study published in September in the Endocrine Society's Journal of Clinical Endocrinology & Metabolism , consuming coffee and caffeine in moderation on a regular basis could help prevent conditions like type 2 diabetes, coronary heart disease, and stroke. The amount the researchers found that had the most protective effects was around 200–300 mg daily, or roughly 2-3 cups of coffee.
Key takeaways:
The researchers compared people who did not consume any caffeine or who drank less than 100 milligrams (mg) per day with people who drank about 200 to 300 mg of caffeine a day, or the equivalent of three coffee drinks.The latter group, who consumed a moderate amount of caffeine, had a 48.1% or 40.7% reduced risk of developing cardiometabolic diseases.The study used data from the UK Biobank with a large sample size of over 360,000 people ages 37–73. Melanie Murphy Richter, MS, RDN , a registered dietitian nutritionist who was not involved in the research, explained that the mechanism through which caffeine may reduce the risk of type 2 diabetes is by enhancing insulin sensitivity , as well as boosting fat metabolism to support overall cardiometabolic health.Experts such as Cheng-Han Chen, MD, a board certified interventional cardiologist who was not involved in the study, cautioned as to overestimating caffeine's benefits and said: "[B]oth coffee and tea are complex beverages that contain hundreds of bioactive compounds, and it is likely that their biological effects extend beyond those of the caffeine itself. Compounds such as flavonoids , alkaloids, and polyphenols , are thought to have antioxidant and anti-inflammatory effects, and might be involved in glucose and lipid metabolism as well."In a nutshell:
A study not yet published in a peer-reviewed journal but recently presented at ACC Asia 2024 in India in August found that people who chronically consume high amounts of caffeine at least five days per week may have an increased risk of cardiovascular disease. This was true even if the study participants were otherwise in good health.
Key takeaways:
For this study, the researchers defined chronic caffeine consumption as drinking any caffeinated beverage—including coffee, tea, soda, and energy drinks—five days a week for over a year.This equaled about 400 milligrams (mg) of caffeine daily, or roughly four cups of coffee, two energy drinks, or 10 cans of soda.The researchers discovered that people who consumed at least 400 mg had increased heart rates and blood pressure over time, and this was even more pronounced for people who consumed 600 mg of caffeine a day.Commenting on their findings, Nency Kagathara, MBBS, lead author of this study and researcher in the Department of Internal Medicine at Zydus Medical College and Hospital in India, said: "Due to its effect on the autonomic nervous system , regular caffeine consumption could put otherwise healthy individuals at risk of hypertension and other cardiovascular events. Increasing awareness of these risks is vital to improve heart health for all."In a nutshell:
According to a study published in the Journal of Stroke on September 27, carbonated drinks, fruit juices and drinks, and too much coffee may increase the risk of experiencing stroke and intracerebral hemorrhage. However, the risks associated with these beverages varied depending on the population and where the participants were geographically located.
Key takeaways:
Drinking more than four cups of coffee daily raised the likelihood of a person having a stroke by 37%. However, drinking less than four cups of coffee daily or a moderate amount daily was not associated with an increased risk of stroke.The data the researchers collected came from a large number of participants from 32 countries.Among other caffeinated beverages, the researchers found that drinking three to four cups of black tea a day—such as Earl Grey or breakfast tea— lowered the risk of stroke by 29%. However, tea's effects differed according to the region in which people lived.While the caffeine in coffee can cause an increase in blood pressure and, therefore, increase stroke risk, Christopher Yi, MD, board certified vascular surgeon at Memorial Orange Coast Medical Center in Fountain Valley, CA, who was not involved in the research, said: "Like most things being consumed, moderation is safer than excessiveness." 
