Abstract
Objective: To perform a dose–response meta-analysis of prospective cohort studies investigating the association between long-term coffee intake and risk of hypertension. Methods: An online systematic search of studies published up to November 2016 was performed. Linear and non-linear dose–response meta-analyses were conducted; potential evidence of heterogeneity, publication bias, and confounding effect of selected variables were investigated through sensitivity and meta-regression analyses. Results: Seven cohorts including 205,349 individuals and 44,120 cases of hypertension were included. In the non-linear analysis, there was a 9% significant decreased risk of hypertension per seven cups of coffee a day, while, in the linear dose–response association, there was a 1% decreased risk of hypertension for each additional cup of coffee per day. Among subgroups, there were significant inverse associations for females, caffeinated coffee, and studies conducted in the US with longer follow-up. Analysis of potential confounders revealed that smoking-related variables weakened the strength of association between coffee consumption and risk of hypertension. Conclusions: Increased coffee consumption is associated with a modest decrease in risk of hypertension in prospective cohort studies. Smoking status is a potential effect modifier on the association between coffee consumption and risk of hypertension.
Highlights
Coffee has been the focus of major attention due to its global consumption and impact on health [1].Historically, coffee consumption was considered to have detrimental effects on health, its contribution to high blood pressure [2]
The inclusion criteria consisted of studies that: (i) are prospective; (ii) evaluated the association of coffee intake and the risk of hypertension in individuals without hypertension at baseline; (iii) assessed and reported hazard ratios (HRs), risk ratios (RRs), or odds ratios (ORs) and 95% CI for hypertension; and (iv) assessed and reported a defined amount of coffee consumption for each category of exposure
To further investigate whether other unmeasured potential confounders should be included in the interpretation of the results, we investigated the distribution of systolic blood pressure, diastolic blood pressure, age, body mass index (BMI), daily intake of sodium and potassium, percentage of smokers, participants with low physical activity and those with type-2 diabetes across categories of coffee consumption
Summary
Coffee consumption was considered to have detrimental effects on health, its contribution to high blood pressure [2]. Coffee contains many other bioactive compounds, such as polyphenols, furans, pyrroles, and maltol, all of which have recently been hypothesized to have potential beneficial effects on human health [3,4]. Meta-analyses of prospective cohort studies show a J-shaped dose–response relationship between coffee consumption and decreased risk of Nutrients 2017, 9, 890; doi:10.3390/nu9080890 www.mdpi.com/journal/nutrients. Studies exploring acute events most likely triggered by coffee-dependent increase in blood pressure showed no substantial increase in mortality due to myocardial infarction [7] and atrial fibrillation [8]. Apart from cardiovascular health, coffee consumption has been hypothesized to affect a number of other conditions, including metabolic status [6] and risk of late-life cognitive impairment [9,10]
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