Evaluation of the Association Between Coffee Consumption, Including Type (Instant, Ground), and Addition of Milk or Sweeteners and New-Onset Hypertension and Potential Modifiers.

Background: The association between coffee consumption and incident hypertension remained inconsistent.

Objective: This study aimed to examine the association of consumption of coffee, including different types (instant and ground) and with different additives, with new-onset hypertension, and evaluate whether genetic variation in caffeine metabolism and inflammation may modify the association.

Design: This study utilized a prospective cohort design.

Participants/setting: A total of 98 765 participants free of hypertension enrolled in the UK Biobank between 2006 and 2010 were included. Dietary coffee consumption was collected using 24-hour dietary recall questionnaires.

Main outcome measures: The study outcome was new-onset hypertension, ascertained by self-reported medical conditions, hospital inpatient records, death registers, and primary care records.

Statistical analyses performed: Cox proportional hazards models were used to estimate hazard ratio and 95% CI. Potential modifying effects were assessed by likelihood ratio testing.

Results: During a median follow-up of 12.1 years, 7090 (7.2%) new-onset cases of hypertension were documented. Overall, regardless of coffee type (instant or ground) and whether adding milk to coffee, there was a U-shaped association between unsweetened coffee consumption and new-onset hypertension, with a 14% to 18% reduction of hypertension risk at >1 to ≤4 drinks per day, whereas a null association was observed between sweetened coffee consumption and the risk of new-onset hypertension. Relative to coffee nonconsumers, the adjusted hazard ratio (95% CI) of new-onset hypertension for participants who drinking unsweetened coffee 1 or fewer, >1 to 2, >2 to 3, >3 to 4, and >4 drinks/day were 0.92 (95% CI 0.85 to 1.00), 0.82 (95% CI 0.76 to 0.89), 0.86 (95% CI 0.79 to 0.96), 0.86 (95% CI 0.77 to 0.96), and 0.88 (95% CI 0.78 to 0.99), respectively. Moreover, a stronger inverse association between moderate consumption of unsweetened coffee and new-onset hypertension was found in participants with higher C-reactive protein levels (P for interaction =.012), whereas an individual's genetic variation in caffeine metabolism did not significantly modify the association (P for interaction = .453).

Conclusions: Regardless of the type of coffee (instant or ground) or the addition of milk to coffee, moderate consumption of unsweetened coffee (>1 to ≤4 drinks/day), but not sweetened coffee, was associated with a lower risk of new-onset hypertension.