LONDON – Drinking three or more cups of caffeinated espresso per day predicted increasing blood pressure and rising blood glucose, according to the results of the Hypertension and Ambulatory Recording Venetia Study (HARVEST), a multicenter, observational study that began in Italy in 1990 and recruited more than 1,000 patients aged 18-45 years who had stage I hypertension and did not have diabetes.
Further, the risk of a cardiovascular event was increased by 50% in these study participants based on a total of 60 events during a mean of 12.5 years of follow-up.
“Controversy still exists about the long-term cardiovascular and metabolic effects of coffee consumption in hypertension,” Dr. Lucio Mos of Hospital San Daniele del Friuli in Udine, Italy, said during a press conference at the annual congress of the European Society of Cardiology.
Dr. Lucio Mos
Stage 1 hypertension was defined as a diastolic blood pressure of 90-99 mm Hg and a systolic blood pressure of 140-159 mm Hg and diagnosed on the basis of six office-based readings obtained on two separate visits. Enrolled participants underwent ambulatory blood pressure monitoring and three office-based measurements were repeated at 1, 2, 3 and 6 months, and at 6-month intervals thereafter. The endpoint was hypertension requiring any antihypertensive treatment according to international guidelines.
During the study, 24-hour urine samples were collected to assess catecholamine levels. Lifestyle factors such as body weight, physical activity, smoking status, and blood glucose were measured. Patients underwent echocardiography.
They were divided into three groups according to their caffeinated coffee intake: 316 (26%) were designated as abstainers because they did not drink coffee; 767 (64%) drank 1-2 cups a day and were categorized as moderate drinkers; and 119 (10%) drank three or more cups of coffee a day and were defined as heavy drinkers.
“I want to underline that, in this part of Italy, we have a population that drinks mainly espresso coffee and drinking American-style coffee is not usual,” Dr. Mos said.
Around 70% of the study population was male, with similar baseline blood pressures and heart rates among the groups. Heavy coffee drinkers tended to be older (37 years) than those who were more moderate drinkers (34 years) or those who abstained (31 years). They had significantly higher body weights (P less than .001), with a body mass index of 26.1 kg/m2 vs. 25.7 kg/m2 and 24.6 kg/m2, respectively.
Dr. Mos reported that in multivariate analysis, coffee consumption was a significant predictor for developing hypertension that required antihypertensive therapy, with a hazard ratio (HR) of 1.5 (95% confidence interval [CI], 1.1-1.19) for heavy drinkers and 1.1 (95% confidence interval, 1.1-1.19) for moderate drinkers, compared to abstainers. The difference was significant (P = .004) only for heavy coffee consumption.
“Coffee consumption was also a predictor of future prediabetes,” Dr. Mos reported. Indeed, the incidence of prediabetes was highest in the heavy coffee drinkers, and significantly predicted the risk of developing prediabetes compared to abstainers (HR, 2, 95% CI, 1.3-3.1. P = .0017). There was a nonsignificant trend for moderate drinkers also to be at risk for prediabetes when compared to nondrinkers (HR, 1.3, 95% CI 0.9-1.7).
Looking at the risk for prediabetes in relation to caffeine metabolism by analyzing patients by their CYP1A2 genotype, it was found that heavy coffee drinkers who were slow metabolizers of caffeine were at highest risk, with a HR of 2.78 (95% CI, 1.32-5.88). Furthermore, individuals were particularly at risk if they were also overweight or obese.
There was a significant (P = .0017) linear relationship found after multivariate adjustment between coffee intake and cardiovascular events such as heart attacks, with the risk increasing with higher coffee intake. Even moderate coffee intake, defined as one to three cups per day, could up the risk of a cardiovascular event when compared to that of non–coffee drinkers.
“The coffee story was very topical a couple of years ago so it is interesting to see it revisited,” said Dr. Ian Graham of Trinity College Dublin and one of the experts who chaired the press briefing on the study results. “We need a randomized controlled trial,” Dr. Graham suggested, noting that there were several prior studies that suggested there were beneficial effects of coffee.
Cochair Dr. José Gonzalez-Juanatey of Hospital Clínico Universitario de Santiago de Compostela in Spain observed: “The recommendation could be that if you are a young or middle-aged, stage 1 hypertensive patient probably you have to reduce your coffee intake. This is the take-home message based on the results of an observational study well performed and well conducted.”