Coffee consumption amongst normotensive individuals has been shown to cause an acute increased in both systolic and diastolic blood pressure, but does not result in long term changes in pressure. The acute effects are likely a result of caffeine causing increased release of adrenaline, which in turn leads to vascular tonal changes. Over the long term negative feedback returns the pressure to baseline. The acute effects of coffee in raising blood pressure appear to decrease with increased consumption, such that regular coffee drinkers demonstrate only small changes in blood pressure following ingestion. Overall, longitudinal studies suggest that regular coffee consumption does not increase the risk of cardiovascular disease. The effects of coffee on hypertensive individuals is less well studied. However, the small number of studies published also shows that habitual coffee consumption in hypertensives is not associated with elevated blood pressure and or increased risk of cardiovascular disease.
For example, a meta-analysis and review of data was been performed on 5 trials identified in a PubMed and EMBASE search, based on papers published up to 30 April 2011. The authors were interested in investigating evidence on the chronic and acute effects of caffeine and coffee intake on the blood pressure in hypertensive individuals as well as identifying correlations between habitual coffee consumption and long-term modifications to blood pressure. Results showed that 200-300mg caffeine produced a mean increase of 9.1mm Hg in systolic blood pressure and 5.7mmHg in diastolic blood pressure. However, this increase only lasted for one hour after ingestion of the caffeine. In other studies, 2 weeks of coffee consumption caused no significant changes to blood pressure compared to a caffeine free diet or decaffeinated coffee. Seven cohort studies also failed to find associations between coffee consumption and cardiovascular disease.
As with normotensive individuals, hypertensives appear to have an acute rise in blood pressure following caffeine ingestion, but the long-term effects do not cause significant blood pressure changes. The actual acute rises in blood pressure appear to be similar between hypertensive and normotensive subjects (2-12mm Hg systolic and 3-11mm Hg diastolic versus 8mm Hg systolic and 6mm Hg diastolic, respectively). Coffee, like tea contains many phytonutrient substances that may confer health benefits to regular consumers. While coffee has developed a reputation for causing high blood pressure, the scientific evidence does not support this contention. In fact, evidence suggests that the phytonutrients such as chlorogenic acid contained within the coffee may provide health benefits to consumers and protect from free radical damage and systemic oxidative stress. Confounding variables such as other lifestyle habits may explain the research claiming detrimental effects for coffee consumption on blood pressure.
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