The impact of caffeine on blood pressure Original paper

In this meta-analysis of randomized controlled trials conducted primarily with participants who had no known health conditions, supplementation with caffeine increased systolic and diastolic blood pressure.

The effect of supplementation with caffeine, compared with a glossary placebo, on systolic and diastolic blood pressure.

390 men and women (average ages of 19–71), of whom 356 had no known health conditions and 34 had type 1 diabetes.

A meta-analysis of 8 randomized controlled trials was performed. Four of the trials were conducted in the United States and 1 trial each was from Ireland, the Netherlands, Spain, and the United Kingdom. The daily dose of caffeine ranged from 240 mg to 600 mg. The intervention duration ranged from 1 to 12 weeks.

Supplementation with caffeine increased systolic blood pressure by 1.9 millimeters of mercury (mmHg) and diastolic blood pressure by 1.7 mmHg, with the certainty of evidence rated moderate for both outcomes.

In dose-response analyses, there were nonlinear relationships between the dose and duration of caffeine and changes in blood pressure. Systolic and diastolic blood pressure appeared to be higher with the lower end and higher end of daily caffeine doses (approximately 200–300 mg and approximately 500–600 mg) and the shorter and longer intervention durations (approximately 1–3 weeks and approximately 10–12 weeks).

The risk of bias was unclear in all of the trials included in the meta-analysis.

In the abstract, the authors state that supplementation with caffeine more effectively increased blood pressure in men than in women. However, this conclusion is not supported by the results of the subgroup analyses.

It was not specified whether the participants were habitual caffeine consumers or not.