Caffeine is a central nervous system stimulant found in various plants such as cocoa beans, coffee, and tea, among others.1 Additionally, caffeine can be synthetically produced and is sometimes added to dietary supplements, drugs, and food products. The short-term effects of caffeine consumption on blood pressure are fairly well catalogued,2–4 but the long-term effects, especially of habitual consumption, on blood pressure in normotensive or hypertensive subjects are still unclear.
Mesas et al. conducted a systematic review and meta-analysis evaluating the effect of caffeine intake (in the form of coffee, tea, or pills) on the blood pressure of hypertensive patients.5 Data was reviewed from three types of studies: controlled trials looking at the acute effects of caffeine consumption (defined as a caffeine intake over <1 week), controlled trials looking at the longer-term effects of caffeine consumption (≥1 week of intake), and cohort studies examining the relationship between regular coffee consumption and cardiovascular disease (CVD). Data analyzed from five cross-over controlled trials (n=85) found that administration of 200 – 300 mg (the equivalent of 1 ½ to 2 cups of coffee) of caffeine caused a mean increase in systolic blood pressure of 8.1 mm Hg (95% confidence interval [CI] [5.7 – 10.6]). The increase in blood pressure was observed in the first hour following intake and lasted three or more hours. In five long-term studies (n=364) with interventions lasting two or more weeks, coffee consumption led to no significant changes in blood pressure as compared to a caffeine-free diet or the consumption of decaffeinated coffee. The seven cohort studies examining the relationship between caffeine intake and CVD in hypertensive patients (n=169,320) did not look for correlations between caffeine intake and hypertension.
Lopez-Garcia et al. conducted a cross-sectional study of 715 hypertensive participants aged 63 years or older examining the relationship between habitual coffee consumption and blood pressure.6 Self-reported caffeine consumption was assessed by diet history and blood pressure was recorded with 24-hour ambulatory monitoring. The regression analysis adjusted for numerous confounding variables including, but not limited to, smoking history, body mass index (BMI), sodium consumption, and anti-hypertensive treatment. Compared to non-coffee-drinkers, the odds ratio for uncontrolled hypertension (average 24-hour ambulatory blood pressure ≥130/90 mm Hg) in participants consuming one cup of coffee a day was 1.95 (95% CI [1.15 – 3.30]), in participants consuming two cups of coffee per day was 1.41 (95% CI [0.75 – 2.68], and in those consuming three or more cups of coffee a day was 2.55 (95% CI [1.28 – 5.09], p for trend=0.05). The authors concluded that habitual coffee consumption is associated with uncontrolled blood pressure.
Nurminen et al. conducted a systematic literature review of controlled clinical and epidemiologic studies on the effects of caffeine or caffeinated beverages on blood pressure.4 The results of cross-sectional or longitudinal studies were inconsistent. Some found habitual caffeine use increased blood pressure. Others found no relation, and some found a small inverse relation.
When reviewing the evidence of the effect of caffeine on blood pressure, it may be important to isolate the effects of caffeine from other effects of coffee, tea, and other caffeinated beverages that are used in some analyses. Some studies, for example, have identified a u-shaped relationship between coffee consumption and blood pressure. Individuals who consume high amounts of coffee or no coffee have a beneficial effect on blood pressure compared to those who consume moderate amounts of coffee.8–11 It has been suggested that components of caffeinated beverages, including polyphenols, soluble fiber, and potassium may have beneficial effects on the cardiovascular system that influence results of some studies.8,12 Similarly, tea and tea derivatives, especially green tea extract, have been shown to have unpredictable effects on blood pressure.13–15 In the Nurses’ Health Study I and II, which analyzed the effects of caffeinated coffee and caffeinated sodas, the authors found an inverse or non-significant relationship between coffee consumption and relative risk (RR) for incident hypertension, but a positive relationship between soda consumption and RR for incident hypertension.11
References
- Turnbull D, Rodricks J V., Mariano GF, Chowdhury F. Caffeine and cardiovascular health. Regul Toxicol Pharmacol 2017; 89 : 165-185.
- Noordzij M, Uiterwaal CSPM, Arends LR, Kok FJ, Grobbee DE, Geleijnse JM. Blood pressure response to chronic intake of coffee and caffeine: a meta-analysis of randomized controlled trials. J HYpertens 2005; 23 (5): 921-928.
- Jee SH, He J, Whelton PK, Suh I, Klag MJ. The effect of chronic coffee drinking on blood pressure: a meta-analysis of controlled clinical trials. Hypertension 1999; 33 (2): 647-652.
- Nurminen M-L, Niittynen L, Korpela R, Vapaatalo H. Coffee, caffeine and blood pressure: a critical review. Eur J Clin Nutr 1999; 53 (11): 831-839.
- Rodriguez-Artalejo F, Lopez-garcia E, Mesas AE, et al. The effect of coffee on blood pressure and cardiovascular disease in hypertensive individuals : a systematic review and meta-analysis 1 – 3. Am J Clin Nutr 2011; 94 (4): 1113-1126.
- Lopez-Garcia E, Orozco-Arbeláez E, Leon-Muñoz LM, et al. Habitual coffee consumption and 24-h blood pressure control in older adults with hypertension. Clin Nutr 2016; 35 (6): 1457-1463.
- Steffen M, Kuhle C, Hensrud D, Erwin PJ, Murad MH. The effect of coffee consumption on blood pressure and the development of hypertension: A systematic review and meta-analysis. J Hypertens 2012; 30 (12): 2245-2254.
- Geleijnse JM. Habitual coffee consumption and blood pressure: an epidemiological perspective. Vasc Heal Risk Manag 2008; 4 : 963-970.
- Hu G, Jousilahti P, Nissinen A, Bidel S, Antikainen R, Tuomilehto J. Coffee consumption and the incidence of antihypertensive drug treatment in Finnish men and women. Am J Clin Nutr 2007; 86 (2): 457-464.
- Klag MJ, Wang N-Y, Meoni LA, et al. Coffee intake and risk of hypertension: the Johns Hopkins precursors study. Arch Intern Med 2002; 162 (6): 657-662.
- Winkelmayer WC, Stampfer MJ, Willett WC, Curhan GC. Habitual caffeine intake and the risk of hypertension in women. JAMA 2005; 294 (18): 2330-2335.
- Di Lorenzo A, Curti V, Tenore GC, Nabavi SM, Daglia M. Effects of tea and coffee consumption on cardiovascular diseases and relative risk factors: an update. Curr Pharm Des 2017; 23 (17): 2474-2487.
- Li G, Zhang Y, Thabane L, et al. Effect of green tea supplementation on blood pressure among overweight and obese adults: a systematic review and meta-analysis. J Hypertens 2015; 33 (2): 243-254.
- Nogueira L de P, Nogueira Neto JF, Klein MRST, Sanjuliani AF. Short-term effects of green tea on blood pressure, endothelial function, and metabolic profile in obese prehypertensive women: a crossover randomized clinical trial. J Am Coll Nutr 2017; 36 (2): 108-115.
- Yarmolinsky J, Gon G, Edwards P. Effect of tea on blood pressure for secondary prevention of cardiovascular disease: a systematic review and meta-analysis of randomized controlled trials. Nutr Rev 2015; 73 (4): 236-246.
