Similar effects of caffeine have been observed in hypertensive subjects. In an intervention trial, caffeine administration to hypertensive subjects raised systolic blood pressure but this effect was no longer observed after the first 24 hours (5).
In a second intervention trial there were no effects on blood pressure of drinking caffeinated coffee or abstaining in patients with borderline or mild hypertension (6). In a cohort study of hypertensive subjects, there were no associations between caffeine consumption and all-cause or cardiovascular disease mortality (7, 8). Hence there is no evidence in hypertensive subjects of a sustained effect of caffeine consumption on blood pressure nor increased death rates from cardiovascular disease.
However, some studies have demonstrated potential negative effects of caffeine on blood pressure. It has been shown that intake of caffeine during behavioural stress in subjects with borderline hypertension elevates blood pressure (9). Subjects with hypertension and subjects with normal blood pressure may respond differently to caffeine. Thus diastolic blood pressure returned to normal more quickly in subjects with normal blood pressure than in subjects with hypertension after caffeine ingestion (10). It has also been claimed that 24 hour monitoring of blood pressure is necessary to reveal all the effects of caffeine on blood pressure (11).
Stockton, California, USA
Brunei, Darussalam Bandar Seri Begawan