Summary: New research links drinking more than six cups of coffee per day with a higher risk of cardiovascular disease.
Source: University of South Australia
Morning ritual for many, essential for some — whether latte, cappuccino or short black — coffee helps people wake up and focus. But how much coffee is safe?
Debates over coffee’s health effects have continued for decades. Recent research from the University of South Australia identifies a threshold at which habitual coffee intake appears to increase cardiovascular risk. According to this study, consuming six or more cups of coffee daily was associated with a rise in the risk of heart disease by as much as 22 percent compared with drinking one to two cups per day.
Cardiovascular disease remains a major public health concern. In Australia, about one in six people are affected, and it is a leading cause of death. The World Health Organization classifies cardiovascular disease as the top cause of mortality worldwide, yet many cases are preventable through lifestyle and medical measures.
Researchers Dr Ang Zhou and Professor Elina Hyppönen from the Australian Centre for Precision Health at UniSA examined long-term coffee consumption together with genetic data related to caffeine metabolism. Their analysis aimed to determine whether genetic differences that alter how quickly a person metabolizes caffeine change the relationship between coffee intake and cardiovascular disease risk.
“Coffee is the world’s most popular stimulant — it helps us feel alert and focused — and people frequently ask, ‘How much caffeine is too much?’” Professor Hyppönen explains. The study links high coffee intake with effects such as raised blood pressure, which is a known risk factor for cardiovascular disease. The findings suggest that six daily cups represents a tipping point where harmful cardiovascular effects begin to appear.
“To support heart health and maintain healthy blood pressure, people should limit their daily coffee to fewer than six cups — in our data, six cups was where caffeine began to negatively affect cardiovascular risk.”
The team analyzed data from the UK Biobank covering 347,077 participants aged 37 to 73 years, including 8,368 incident cases of cardiovascular disease. They investigated the role of the CYP1A2 gene, which influences how rapidly an individual metabolizes caffeine, and a broader genetic score for caffeine metabolism. Although some people carry genetic variations that enable faster caffeine clearance, the study found that these differences did not offset the increased cardiovascular risk associated with very high coffee consumption.
Specifically, risk patterns were nonlinear: compared with drinking one to two cups per day, nondrinkers, decaffeinated coffee drinkers, and those consuming more than six cups daily showed higher odds of cardiovascular disease — increases of about 11 percent, 7 percent and 22 percent, respectively. The researchers did not find evidence that genotype for CYP1A2 or the broader caffeine genetic score altered these associations.
Professor Hyppönen notes that while some people metabolize caffeine faster, this genetic advantage did not translate into a meaningful reduction in cardiovascular risk for heavy coffee drinkers. With an estimated three billion cups of coffee enjoyed worldwide every day, understanding safe consumption limits matters for population health.
“Moderation is key,” she says. “Enjoy coffee for its benefits, but be mindful of intake — overindulging may carry measurable risks to your heart.”
Source:
University of South Australia
Media contacts:
Annabel Mansfield – University of South Australia
Image source:
Image adapted from the Cedars-Sinai news release.
Original research: Closed access
“Long-term coffee consumption, caffeine metabolism genetics, and risk of cardiovascular disease: a prospective analysis of up to 347,077 individuals and 8,368 cases.” Ang Zhou and Elina Hyppönen. American Journal of Clinical Nutrition. doi: 10.1093/ajcn/nqy297
Abstract (summary)
Background:
Coffee is widely consumed and often considered safe or beneficial, but some evidence links coffee to higher risk of myocardial infarction and hypertension in individuals with certain CYP1A2 variants that reduce caffeine metabolism.
Objectives:
The study assessed whether CYP1A2 genotype or a genetic score for caffeine metabolism modifies the relationship between habitual coffee intake and cardiovascular disease risk.
Methods and results:
Using genetic and coffee intake data from 347,077 UK Biobank participants, including 8,368 incident cardiovascular cases, the researchers applied logistic regression to test associations. Compared with drinking one to two cups daily, nondrinkers, decaffeinated coffee drinkers, and those consuming more than six cups per day showed elevated cardiovascular risk (roughly 11%, 7%, and 22% higher odds, respectively). Genetic markers for caffeine metabolism were not associated with cardiovascular disease, and there was no interaction between genotype and coffee intake in relation to cardiovascular risk.
Conclusions:
Heavy coffee consumption was associated with a modest increase in cardiovascular disease risk, and this relationship was not modified by common genetic variants that influence caffeine metabolism.