Chocolate Intake and Risk of Atrial Fibrillation

Shattered homemade chocolate with cocoa powder

By Martina M. McGrath, MD
June 7, 2017

Cocoa beans were highly prized by the Aztecs, used in religious ceremonies, traded for goods, and believed to have medicinal purposes.1 While cocoa beans are a rich source of anti-inflammatory flavonols and antioxidants, it is reported that modern manufacturing processes destroy most of these potentially beneficial substances.2 Furthermore, modern chocolate typically contains large quantities of sugar, meaning this popular indulgence is an unlikely health food supplement. Despite this, epidemiological studies have associated moderate chocolate consumption with reduced risk of myocardial infarction and several cardiovascular end points.3,4

A group of investigators from Aarhus University in Denmark and Harvard Medical School have recently published an analysis showing a decreased risk of atrial fibrillation in individuals with moderate chocolate intake.5 Participants underwent baseline assessment for anthropometric data and assessment of diet by dietary recall and food frequency questionnaires. Using registry data of hospital admissions, the authors tracked occurrence of atrial fibrillation and flutter in over 55,000 patients for 13.5 years.

During follow up, 3346 cases of atrial fibrillation were recorded. Compared with intake of less than once per month, progressively higher chocolate intake of 1-3 servings/month, up to 2-6 servings/week was associated with 11-20% lower rates of atrial fibrillation, with protection seen in both men and women.  The association remained intact after control for multiple variables including age, caloric intake, BMI, blood pressure, smoking, and caffeine intake among others.

Limitations of this study include the homogenous study population (Caucasian Northern Europeans), the limited data of actual diet over the follow-up period, and the use of only hospital admissions as the primary source of data for the occurrence of atrial fibrillation. Furthermore, participants with higher chocolate intake had lower baseline incidence of diabetes, hypertension, and cardiovascular disease. Therefore, whether the results of this study simply reflect a healthier baseline population versus some protective effect of chocolate intake cannot be established from this type of analysis. However, the COSMOS trial, currently enrolling 18,000 patients to take cocoa flavanol supplements versus placebo6 may address some of these questions and give some more firm data as to potential benefits of cocoa products for cardioprotection.


  1. Accessed 4th June 2017.
  2. Payne MJ, Hurst WJ, Miller KB, et al. Impact of fermentation, drying, roasting, and Dutch processing on epicatechin and catechin content of cacao beans and cocoa ingredients. J Agric Food Chem 2010;58:10518–27.
  1. Kwok CS, Boekholdt SM, Lentjes MA, et al. Habitual chocolate consumption and risk of cardiovascular disease among healthy men and women. Heart 2015;101:1279–87.
  1. Larsson SC, Åkesson A, Gigante B, et al. Chocolate consumption and risk of myocardial infarction: a prospective study and meta-analysis. Heart 2016;102:1017–22.
  1. Mostofsky E, Berg Johansen M, Tjønneland A et al. Chocolate intake and risk of clinically apparent atrial fibrillation: the Danish Diet, Cancer, and Health Study. Heart Published Online First: May 23rd 2017 doi:10.1136/ heartjnl-2016-310357.
  2. Accessed 4th June 2017.

Headshot of Dr. McGrathDr. Martina McGrath is an Instructor in Medicine at Harvard Medical School, and a member of the Renal Division, Department of Medicine, at Brigham and Women’s Hospital, both in Boston. Dr. McGrath is the Medical Editor for the Trends in Medicine blog.

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