Science

The State of Coffee in the CCU

I have heard some chatter among the patients on the cardiac care unit regarding whether they may safely indulge in a daily cup of joe. I have also noticed that when providers are placing diet orders, there is an option for decaffeinated vs caffeinated coffee. As a curious, caffeinated medical student, I found myself asking what exactly are the cardiac risks associated with coffee and caffeine? 

The history of coffee is marred by unsubstantiated claims that it is harmful to human health. However, there is growing evidence and increasing acceptance of coffee’s health benefits, including: improved mood and concentration1,2, decreased risk of dementia3, as well as decreased risk of diabetes4,5, and cancer among other benefits attributed to its antioxidant effects6,7. Furthermore, some analyses have demonstrated coffee to be inversely associated with mortality8.These studies by no means establish coffee as a panacea. However, they call into question the practice of depriving patients one of life’s simple pleasures in the name of health. 

The exact origins of theorized cardiac risks of coffee remain unclear. However, studies began emerging on the topic in the 1960s9.  By the 1980s numerous studies were published demonstrating an association with poor cardiovascular health. Some of the specific outcomes measured include hypertension, hyperlipidemia, and arrhythmias10,11. The conclusions of subsequent meta-analyses did not show consistent correlations. However, the idea that coffee is bad for the heart prevailed throughout this period. 

One of the most notorious claims is that coffee induces or exacerbates cardiac arrhythmias. A survey of 697 providers from 1988 revealed that 80-90% recommended moderating caffeine intake in patients with known tachycardia, palpitations, and arrhythmia, yet it is unclear how this consensus arose12. On evaluation of the medical literature of 2022, it seems clear that a positive correlation between arrhythmias and caffeine does not exist. If anything, recent analyses demonstrate a protective effect13,14.  For example, a recent prospective cohort study of over 400,000 individuals revealed that each additional daily cup of coffee was associated with a 3% reduced risk of developing an arrhythmia15.

There are a few proposed mechanisms for this phenomenon. The most popular of which seems to be the activity of caffeine on adenosine receptors. Caffeine is known to block adenosine receptors, which results in a prolonged left atrial refractory period, effectively reducing the likelihood of atrial arrhythmias. Coffee’s antioxidant effects may also play a role, as it is known that inflammation can lead to arrhythmias via multiple pathways. Lastly, although it may seem counterintuitive, the catecholaminergic properties of caffeine may be protective against PVCs, as well as certain arrhythmias triggered by enhanced vagal tone. Research remains ongoing regarding the physiologic effects of caffeine on the cardiac conduction system.

Although arrhythmias are the most cited adverse cardiac outcome among coffee drinkers, hypertension and hyperlipidemia have also been implicated10. Studies have been unanimous in detecting slight increases in both systolic and diastolic blood pressures for up to 3 h after caffeine ingestion17. Although it of note, that studies which implicated coffee in elevated blood pressures and increased stroke risk were performed among non-coffee drinkers or participants who had abstained from caffeine intake prior to the study. This is an important distinction because it has been established that humans develop caffeine tolerance quite quickly, and the same risks were not observed among habitual drinkers or research participants with prolonged exposure18. In fact, some studies show that habitual consumption of coffee or tea may reduce risk of hypertension due the actions of phenolic compounds, specifically chlorogenic acids17.

An interesting distinction has been made regarding the effects of coffee on lipid levels. It appears to be dependent on the brewing method. Boiled coffee is associated with a rise in cholesterol, while drinking filtered coffee is not. This is because boiling methods extract more diterpenes from beans and fail to filter them out from the result17.  The clinical relevance of this distinction is unclear. Overall caffeine has a favorable metabolic profile, as it increases resting metabolic rate and energy expenditure and promoting cellular thermogenesis and lipolysis19. 

Based on current data, it appears that coffee does not pose an imminent threat to cardiovascular health. Future research into the potential benefits of coffee is ongoing and will provide further insight on how to best counsel patients. Considering that on average, it takes approximately 17 years for cardiovascular research to translate to changes in clinical practice20, it is understandable that patients with heart disease continue to approach coffee with caution. It is important for providers to counsel patients on the risks and benefits of caffeinated drinks, which are a morning ritual for many.  It may be of particular importance in the CCU, where many patients are already struggling to implement other lifestyle and dietary changes to benefit their cardiac health.

References

  1. Nehlig, Astrid. “Is Caffeine a Cognitive Enhancer?” Journal of Alzheimer’s Disease, vol.20, no. s1, 2010, https://doi.org/10.3233/jad-2010-091315. 
  2. Lucas, Michel. “Coffee, Caffeine, and Risk of Depression among Women.” Archives of Internal Medicine, vol. 171, no. 17, 2011, p. 1571., https://doi.org/10.1001/archinternmed.2011.393. 
  3. Beydoun, May A., et al. “Caffeine and Alcohol Intakes and Overall Nutrient Adequacy Are Associated with Longitudinal Cognitive Performance among U.S. Adults.” The Journal of Nutrition, vol. 144, no. 6, 2014, pp. 890–901., https://doi.org/10.3945/jn.113.189027. 
  4. Kolb, Hubert, et al. “Coffee and Lower Risk of Type 2 Diabetes: Arguments for a Causal Relationship.” Nutrients, vol. 13, no. 4, 2021, p. 1144., https://doi.org/10.3390/nu13041144. 
  5. Shahinfar, Hossein, et al. “Coffee Consumption and Cardiovascular Diseases and Mortality in Patients with Type 2 Diabetes: A Systematic Review and Dose–Response Meta-Analysis of Cohort Studies.” Nutrition, Metabolism and Cardiovascular Diseases, vol. 31, no. 9, 2021, pp. 2526–2538., https://doi.org/10.1016/j.numecd.2021.05.014. 
  6. Hayakawa, Sumio, et al. “Anti-Cancer Effects of Green Tea Epigallocatchin-3-Gallate and Coffee Chlorogenic Acid.” Molecules, vol. 25, no. 19, 2020, p. 4553., https://doi.org/10.3390/molecules25194553. 
  7. Colombo, Raffaella, and Adele Papetti. “Decaffeinated Coffee and Its Benefits on Health: Focus on Systemic Disorders.” Critical Reviews in Food Science and Nutrition, vol. 61, no. 15, 2020, pp. 2506–2522., https://doi.org/10.1080/10408398.2020.1779175. 
  8. Loftfield E, Cornelis MC, Caporaso N, Yu K, Sinha R, Freedman N. Association of Coffee Drinking With Mortality by Genetic Variation in Caffeine Metabolism: Findings From the UK Biobank. JAMA Intern Med. 2018 Aug 1;178(8):1086-1097. doi: 10.1001/jamainternmed.2018.2425. PMID: 29971434; PMCID: PMC6143111.
  9. Paul O, Lepper MH, Phelan WH, Dupertuis GW, Macmillan A, Mc KH, Park H. A longitudinal     study of coronary heart disease. Circulation. 1963; 28:20–31. [PubMed: 13941964]
  10. Robertson D, Frolich JC, Carr RK, Watson JT, Hollifield JW, Shand DG, Oates JA. Effects of caffeine on plasma renin activity, catecholamines and blood pressure. N Engl J Med. 1978; 298:181–186. [PubMed: 339084] 
  11. Dobmeyer DJ, Stine RA, Leier CV, Greenberg R, Schaal SF. The arrhythmogenic effects of caffeine in human beings. N Engl J Med. 1983; 308:814–816. [PubMed: 6835272]
  12. Hughes, John R., et al. “A Survey of Physician Advice about Caffeine.” Journal of Substance Abuse, vol. 1, no. 1, 1988, pp. 67–70., https://doi.org/10.1016/s0899-3289(88)80009-9.
  13. Cheng M, Hu Z, Lu X, Huang J, Gu D. Caffeine intake and atrial fibrillation incidence: dose response meta-analysis of prospective cohort studies. Can J Cardiol. 2014 Apr;30(4):448-54. doi: 10.1016/j.cjca.2013.12.026. Epub 2014 Jan 2. PMID: 24680173.
  14. Caldeira D, Martins C, Alves LB, Pereira H, Ferreira JJ, Costa J. Caffeine does not increase the risk of atrial fibrillation: a systematic review and meta-analysis of observational studies. Heart. 2013 Oct;99(19):1383-9. doi: 10.1136/heartjnl-2013-303950. PMID: 24009307.
  15. Kim, Eun-jeong, et al. “Coffee Consumption and Incident Tachyarrhythmias.” JAMA Internal Medicine, vol. 181, no. 9, 2021, p. 1185., https://doi.org/10.1001/jamainternmed.2021.3616.
  16. Larsson SC, Drca N, Jensen-Urstad M, Wolk A. Coffee consumption is not associated with increased risk of atrial fibrillation: results from two prospective cohorts and a meta-analysis. BMC Med. 2015 Sep 23;13:207. doi: 10.1186/s12916-015-0447-8. PMID: 26394673; PMCID: PMC4579587.
  17. Cano-Marquina, A., et al. “The Impact of Coffee on Health.” Maturitas, vol. 75, no. 1, 2013, pp. 7–21., https://doi.org/10.1016/j.maturitas.2013.02.002. 
  18. Mesas, Arthur Eumann, et al. “The Effect of Coffee on Blood Pressure and Cardiovascular Disease in Hypertensive Individuals: A Systematic Review and Meta-Analysis.” The American Journal of Clinical Nutrition, vol. 94, no. 4, 2011, pp. 1113–1126., https://doi.org/10.3945/ajcn.111.016667. 
  19. Papukashvili, Dimitri, et al. “Attenuation of Weight Gain and Prevention of Associated Pathologies by Inhibiting SSAO.” Nutrients, vol. 12, no. 1, 2020, p. 184., https://doi.org/10.3390/nu12010184. 
  20. Morris ZS, Wooding S, Grant J. The answer is 17 years, what is the question: understanding time lags in translational research. J R Soc Med. 2011;104(12):510-520. doi:10.1258/jrsm.2011.110180
Katherine Bracamontes
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Katherine Bracamontes is a student at The University of Arizona College of Medicine-Phoenix class of 2023. She graduated from the University of Southern California in 2015 with a B.S. in Lifespan Health. While living in California she became involved with her local radio station, which fostered an interest in community culture and journalism. Katherine enjoys live music and hiking at a very, very leisurely pace.