title: Caffeine raises blood pressure at work.
abstract: OBJECTIVE
  The study investigated the effects of moderate doses of caffeine on ambulatory blood pressure and heart rate during workday activities.
  
  
  METHODS
  Healthy, nonsmoking, habitual coffee drinkers (N = 21) received daily doses of 100 mg and 500 mg of caffeine on 2 days in a crossover design. Treatment order was random and counterbalanced, and administration was double-blind. Ambulatory monitoring was conducted for 6 to 9 hours during normal workday activities and diary entries were completed at each measurement. Ambulatory data were analyzed for the effects of caffeine dose, controlling for variations in posture, physical activity, and perceived stress.
  
  
  RESULTS
  The average workday blood pressure and heart rate were significantly higher when the higher dose of caffeine was consumed. Controlling for other factors, dose-related differences were 4 mm Hg for systolic and 3 mm Hg for diastolic blood pressure, and were 3 bpm for heart rate.
  
  
  CONCLUSIONS
  Results support earlier evidence that caffeine raises blood pressure at work, and demonstrate that these pressor effects are independent of changes in posture, physical activity, or stress. Daily blood pressure increases associated with caffeine consumption could increase the risk of developing cardiovascular diseases. In addition, caffeine consumption effects might confound ambulatory investigations of the cardiovascular effects of other psychosocial, personality, or health-behavior factors.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, North Carolina 27710, USA. jdlane@acpub.duke.edu
authors.forename: J D
authors.initials: JD
authors.lastname: Lane
authors.forename: B G
authors.initials: BG
authors.lastname: Phillips-Bute
authors.forename: C F
authors.initials: CF
authors.lastname: Pieper
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000187:drug effects*; D015924:Blood Pressure Monitors; D002110:Caffeine / Q000008:administration & dosage / Q000009:adverse effects*; D018592:Cross-Over Studies; D003971:Diastole / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D013599:Systole / Q000187:drug effects; D017132:Workplace
chemical_list: D002110:Caffeine