Is coffee good for the heart?

Drinking two to three cups of coffee daily is good for the health, lowering the risk of cardiovascular disease (CVD) and even promoting longevity in individuals with or without heart problems, according to three studies presented at the American College of Cardiology’s (ACC) Annual Scientific Session 2022.

“Because coffee can quicken heart rate, some people worry that drinking it could trigger or worsen certain heart issues. This is where general medical advice to stop drinking coffee may come from. But our data suggest that daily coffee intake shouldn't be discouraged, but rather included as a part of a healthy diet for people with and without heart disease,” said senior study author Peter Kistler, professor and head of arrhythmia research at the Alfred Hospital and Baker Heart Institute in Melbourne, Australia, in a statement.

“We found coffee drinking had either a neutral effect, meaning that it did no harm, or was associated with benefits to heart health,” he added.

Cardiovascular events

Kistler and colleagues had conducted three separate studies using data from the UK Biobank, which involved over half a million people who were followed for at least 10 years. They looked at varying levels of coffee intake (0, <1, 1, 2–3, 4–5, >5 cups per day) in relation to the risks of arrhythmias, CVD (coronary heart disease [CHD], cardiac failure, and stroke), and total and heart-related deaths among individuals with and without CVD.

In the first study (n=382,535, mean age 57 years, 52 percent female), daily intake of 2–3 cups/day yielded about 9–15 percent reduction in the risks of incident CVD overall (hazard ratio [HR], 0.91), CHD (HR, 0.90), cardiac failure (HR, 0.85) and all-cause mortality (HR, 0.86). Stroke risk was lowest at <1 cup/day (HR, 0.85, CI 0.75-0.96), while cardiovascular mortality risk was lowest at 1 cup/day (HR, 0.83). There was a U-shaped association seen between coffee intake and incident arrhythmia, with the lowest risk at 2–3 cups/day (HR, 0.92; p<0.01 for all). [ACC 2022, abstract 41]

Coffee conferred consistent cardioprotective benefits to patients with CVD or arrhythmia, as shown in the results of the second study. Among CVD patients (n=34,279, 19.6 percent deaths), coffee intake at any level had no negative health consequences, including the development of atrial fibrillation or flutter (AF/AFL). Conversely, there was evidence of improved survival at 2–3 cups/day (HR, 0.92; p=0.03). [ACC 2022, abstract 36]

The same was true for patients with an arrythmia (n=24,111), for whom mortality reduction with coffee drinking was most pronounced at 1 cup/day (HR, 0.85; p<0.01). Those with AF/AFL, specifically, also saw improved survival at 1 cup/day (HR, 0.82; p<0.01).

“Clinicians generally have some apprehension about people with known CVD or arrhythmias continuing to drink coffee, so they often err on the side of caution and advise them to stop drinking it altogether due to fears that it may trigger dangerous heart rhythms,” Kistler said. “But our study shows that regular coffee intake is safe … for people with heart disease.”

Although drinking two to three cups of coffee daily did seem to be the most beneficial, Kistler advised against increasing one’s coffee intake, particularly if it makes people feel anxious or uncomfortable.

“There is a whole range of mechanisms through which coffee may reduce mortality and have these favourable effects on CVD,” he noted. “Coffee drinkers should feel reassured that they can continue to enjoy coffee even if they have heart disease. Coffee is the most common cognitive enhancer—it wakes you up, makes you mentally sharper, and it’s a very important component of many people’s daily lives.”

Coffee subtypes

In the last study, Kistler and his team assessed whether coffee subtypes exerted varying effects on cardiovascular outcomes. They looked at participants who consumed ground (n=73,027), instant (n=167,399), and decaffeinated (n=57,615) coffee as well as those who do not drink coffee (n=84,494). [ACC 2022, abstract 4]

Ground and instant coffee intake at 1–5 cups/day appeared to be protective against arrhythmia, CVD, coronary disease, cardiac failure, and stroke risks. The lowest risk for CVD was seen at 2–3 cups/day for both ground (HR, 0.83) and instant (HR, 0.91) coffee. Meanwhile, decaffeinated coffee had a neutral effect on incident arrhythmia and CVD risks, except for cardiac failure.

All subtypes had a favourable effect on total and CV mortality outcomes, with the lowest total mortality risk seen at 2–3 cups/day for ground (HR, 0.74), instant (HR, 0.90), and decaffeinated (HR, 0.85; p<0.01 for all) coffee.

Kistler acknowledged several important limitations to the studies. First, the team was unable to adjust for dietary factors that may play a role in CVD, and for any creamers, milk, or sugar consumed. Additionally, coffee intake was based on self-report via a questionnaire.

Further research, especially randomized trials, is needed to validate the current findings and to determine whether they extend to populations other than Whites, he said.