The American Heart Association (AHA) has issued a new scientific statement concluding that for most adults, consuming up to 400 milligrams of caffeine per day—equivalent to five 237-millilitre cups of coffee—is safe and does not increase cardiovascular risk. Published in the journal Circulation, the review found that regular consumption of black, unsweetened coffee was associated with a lower risk of type 2 diabetes, heart disease, stroke, heart failure and some irregular heart rhythms. Gregory M. Marcus, chair of the statement’s writing group, said that caffeine from coffee is a daily staple for millions and that the evidence supports the safety of moderate intake.

The AHA cautioned that adding sugar, flavoured syrups, milk or cream likely diminishes these potential benefits, and that more research is needed to understand the impact of such additives. The statement drew a sharp distinction between coffee and high-caffeine energy drinks, which can contain three to four times the caffeine concentration and have been linked to hypertension and arrhythmias. It also noted nuanced effects on blood pressure: drinking one to three cups per day was associated with a higher risk of developing hypertension in people with normal blood pressure, while more than three cups per day was linked to a lower risk. Cafestol, a compound present in both regular and decaffeinated coffee, was associated with higher levels of LDL cholesterol.

The guidance arrives as coffee solidifies its position as the most consumed beverage among US adults, surpassing bottled water. According to the National Coffee Association’s spring 2024 report, 66 per cent of adults had consumed coffee in the previous day, compared with 64 per cent for bottled water. The average intake among coffee drinkers was 2.8 cups per day, with home preparation reaching its highest level since 2012, driven by remote work and cost pressures.

Very high doses of caffeine can cause anxiety, insomnia and palpitations, the AHA noted. Separate dietary analyses have warned that excessive coffee consumption can disrupt sleep and lead to long-term daytime fatigue. The statement did not alter existing guidance for pregnant women, for whom other health bodies recommend limiting caffeine to 200 milligrams per day. The AHA emphasised that individual responses to caffeine vary by genetics, metabolism and age, and that the findings apply to most adults without specific contraindications.