Improved detection of a blood pressure response to dietary intervention with 24-hour ambulatory monitoring.

Ambulatory blood pressure (ABP) monitoring was undertaken in 25 hypertensives on beta-blocker monotherapy who completed a double-blind crossover trial to compare the effects of fish oil and corn oil supplements on BP. Clinic BP was measured with a Dinamap monitor on two consecutive days at the end of each treatment phase. ABP was recorded during the intervening 24-h period with a Spacelabs 90207 monitor. Averages of 24-h, daytime, and nighttime ABP readings correlated closely with Dinamap readings. Within-subject BP differences between fish oil and corn oil treatment were similar for Dinamap (3.2 +/- 1.8/2.5 +/- 1.0 mm Hg) and for 24-h ABP (2.5 +/- 1.0/2.3 +/- 0.8 mm Hg), but were more significant with the latter. Thus detection of the antihypertensive effects of dietary intervention can be improved by the use of ABP.