(Medical Xpress) -- In a new study presented in The American Journal of Clinical Nutrition researchers presented new data showing that there is no definitive connection between coffee consumption and hypertension, or high blood pressure. Previous studies which had once made a connection between the two were only study participants for a short time (less than 85 days).
Zhenzhen Zhang from the Department of Epidemiology at Michigan State University and his colleagues decided to Meta-analyze and systemically review previous studies. They searched electronic records from MEDLINE, EMBASE, Agricola, and Cochrane Library and gathered information from six previous studies that had followed coffee drinkers over long periods of time, some as long as 33 years.
From these studies 172,567 subjects were included and of those 37,135 showed positive for hypertension. With a reference based on no coffee consumption at all and a cup size being 237mL, they found the relative risks for hypertension were 1.09 for those drinking 1-3 cups/day, 1.07 for those drinking 3-5 cups/day, and 1.08 for those drinking greater than 5 cups/day. Based on these results, the greatest risk category is in those drinking 1-3 cups/day.
Researchers believe the study is limited by things such as possible differences in what is considered a serving size, the fact some of the studies used caffeinated and decaffeinated coffee, different types and brew strengths of coffee, as well as other possible factors.