(Press-News.org) In the largest study of its kind, an investigation by UC San Francisco has found no evidence that moderate coffee consumption can cause cardiac arrhythmia.
In fact, each additional daily cup of coffee consumed among several hundred thousand individuals was associated with a 3 percent lower risk of any arrhythmia occurring, including atrial fibrillation, premature ventricular contractions, or other common heart conditions, the researchers report. The study included a four-year follow up.
The paper is published July 19, 2021, in JAMA Internal Medicine.
"Coffee is the primary source of caffeine for most people, and it has a reputation for causing or exacerbating arrhythmias," said senior and corresponding author Gregory Marcus, MD, professor of medicine in the Division of Cardiology at UCSF.
"But we found no evidence that caffeine consumption leads to a greater risk of arrhythmias," said Marcus, who specializes in the treatment of arrhythmias. "Our population-based study provides reassurance that common prohibitions against caffeine to reduce arrhythmia risk are likely unwarranted."
While some professional societies suggest avoiding caffeinated products to lower the risk for arrhythmia, this connection has not been consistently demonstrated - indeed, coffee consumption may have anti-inflammatory benefits and is associated with reduced risks of some illnesses including cancer, diabetes, and Parkinson disease.
In the new study, UCSF scientists explored whether habitual coffee intake was associated with a risk of arrhythmia, and whether genetic variants that affect caffeine metabolism could modify that association. Their investigation was conducted via the community-based UK Biobank, a prospective study of participants in England's National Health Services.
Some 386,258 coffee drinkers took part in the coffee research, with an average mean age of 56 years; slightly more than half were female. It was an unprecedented sample size for this type of inquiry.
In addition to a conventional analysis examining self-reported coffee consumption as a predictor of future arrhythmias, the investigators employed a technique called "Mendelian Randomization," leveraging genetic data to infer causal relationships. As those with the genetic variants associated with faster caffeine metabolism drank more coffee, this analysis provided a method to test the caffeine-arrhythmia relationship in a way that did not rely on participant self-report and should have been immune to much of the confounding inherent to most observational studies.
With a mean four-year follow up, data were adjusted for demographic characteristics, health and lifestyle habits.
Ultimately, approximately 4 percent of the sample developed an arrhythmia. No evidence of a heightened risk of arrhythmias was observed among those genetically predisposed to metabolize caffeine differently. The researchers said that higher amounts of coffee were actually associated with a 3 percent reduced risk of developing an arrhythmia.
The authors noted limitations including the self-reporting nature of the study, and that detailed information on the type of coffee - such as espresso or not - was unavailable.
"Only a randomized clinical trial can definitively demonstrate clear effects of coffee or caffeine consumption," said Marcus. "But our study found no evidence that consuming caffeinated beverages increased the risk of arrhythmia. Coffee's antioxidant and anti-inflammatory properties may play a role, and some properties of caffeine could be protective against some arrhythmias."
Co-authors are Eun-jeong Kim, MD; Thomas J. Hoffmann, PhD; Gregory Nah, MA; Eric Vittinghoff, PhD; and Francesca Delling, MD, all of UCSF.
Disclosures can be found in the paper.
About UCSF Health: UCSF Health is recognized worldwide for its innovative patient care, reflecting the latest medical knowledge, advanced technologies and pioneering research. It includes the flagship UCSF Medical Center, which is ranked among the top 10 hospitals nationwide, as well as UCSF Benioff Children's Hospitals, with campuses in San Francisco and Oakland, Langley Porter Psychiatric Hospital and Clinics, UCSF Benioff Children's Physicians and the UCSF Faculty Practice. These hospitals serve as the academic medical center of the University of California, San Francisco, which is world-renowned for its graduate-level health sciences education and biomedical research. UCSF Health has affiliations with hospitals and health organizations throughout the Bay Area. Visit http://www.ucsfhealth.org/. Follow UCSF Health on Facebook or on Twitter
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