Moderate coffee consumption leads to reduced cardiovascular disease, lower prevalence of diabetes and hyperlipidaemia, lower body mass index, better renal functions and higher creatinine clearance levels. There was no evidence, however, that increasing coffee consumption to three to five cups per day would lead to further improvements.
A detailed study conducted by a team from the University of Athens on the Aegean island of Ikaria has demonstrated that moderate consumption of coffee by hypertensive elderly individuals can lead to improvements in aortic distensibility, according to a presentation at the European Society of Cardiology's Congress 2010 in Stockholm.
Distensibility is a measure of the elasticity of arteries, and low levels have long been recognised as an indicator of atherosclerosis and a reliable predictor of future cardiovascular events. By increasing the load on the heart, hypertension leads to vascular changes and neuro-hormonal activation which causes increases in vascular stiffness and reduced elasticity.
Between June and October 2009, researchers from the University of Athens conducted a health and nutrition survey using a target group of 343 men and 330 women aged between 65 and 100 -- all of whom were long-term residents of Ikaria. The island was selected because of its population's high life expectancy, with an above-average proportion of residents over 90 years of age. Consideration was given to a wide range of socio-demographic, bio-clinical, lifestyle and dietary characteristics related to cardiovascular risk factors such as hypertension, diabetes, hypercholesterolemia, obesity and anthropometric indices. Physical activity status and biochemical parameters related to cardiovascular risk were also evaluated.
Coffee consumption was particularly measured during the initial phase of the study because it is a deeply embedded social tradition within the Greek population, and also because of conflicting evidence of its impact on cardiovascular health. Doctor Christina Chrysohoou, the study coordinator, noted, "As far as the effect of coffee on hypertension is concerned, the pressor response to caffeine seems to be more pronounced in hypertensive or hypertension-prone subjects than in normo-tensive ones. For this reason, our study became focused on a sub-group of some 235 hypertensive subjects, and we measured the impact of daily coffee consumption using echocardiographic indices of aortic distensibility."
To be classified within this sub-group of 235 individuals, subjects had to meet certain criteria that included a known history of hypertension, that they were under dietary or medical treatment, or that they had average blood-pressure levels above the upper limit of the normal range. Aortic distensibility for each of these 235 residents was calculated non-invasively by an established mathematical equation using the echocardiographic measurements of systolic and diastolic diameters of aortic root. Dietary habits were evaluated using a special, repeatable, semi-quantitative food-frequency questionnaire that had been previously validated by experts within the University of Athens in collaboration with the Nutrition Science and Dietetics Department of Harokopio University.
The analysis conclusively illustrates the beneficial effects on aortic distensibility of moderate coffee consumption. The research attributes this to the polyphenolic compounds found in coffee, especially traditional Greek blends that are high in diterpenes such as cafestol and kahweol. The effect of chlorogenic acid is reported to be associated with nitric oxide, as caffeic and ferulic acids appear to improve vascular function by reducing oxidation and enhancing the bio-availability of nitric oxide. Moreover, other micronutrients, including flavonoids, magnesium, potassium, niacin and vitamin E, contribute to the observed health effects of coffee consumption, mainly because of their anti-oxidant properties. However, in hypertensive patients the balance between nitric oxide and superoxide production is already damaged, so the impact of the beneficial compounds present in coffee is possibly not strong enough to offer a protective effect through increased consumption.
Doctor Chrysohoou summarises the findings, "The study revealed that moderate coffee consumption (between one and two cups per day) is associated with higher values of aortic distensibility when compared with other hypertensive elderly individuals taking less quantities of coffee. Adjustments were made for various factors such as age, gender, physical activity status, creatinine levels, BMI and diabetes mellitus. There was also evidence that moderate coffee consumption leads to reduced cardiovascular disease, lower prevalence of diabetes and hyperlipidaemia, lower body mass index, better renal functions and higher creatinine clearance levels. There was no evidence, however, that increasing coffee consumption to three to five cups per day would lead to further improvements in aortic distensibility."