Abstract MP042: Higher Levels of Sodium Density (mg/kcal) are Associated With Increased Blood Pressure Independent of Absolute Sodium (mg): the DASH Sodium Trial
Introduction: Dietary recommendations for Na are expressed as absolute amounts, that is, mg of Na/d rather than as Na density (mg/kcal). The DASH-Na dose-response trial tested the impact of varying Na density on BP, that is, the absolute dose of Na received at the low, medium, and high levels depended on energy intake. For example, a dose of 3,600 mg was high density in individuals with average energy intake but was medium density in individuals with higher energy intake.
Objective: Evaluate whether the effect of Na density on BP was independent of absolute Na.
Methods: In the DASH-Na trial, participants with pre-or stage 1 hypertension were randomly assigned to a control or DASH diet; on both diets, participants were fed each of three Na levels in random order. We analyzed data from 378 Non-Hispanic Black and White participants (ages 23-76 yr, baseline BP 135/86). Using a mixed effects model, level of Na density (low, medium, or high) was added to a model of absolute Na on BP to determine if the effect of Na density on BP was independent of absolute Na, with adjustment for randomized diet, cohort, carryover, clinical center, age, sex, race, and interactions of diet with absolute Na and Na density.
Results: At the same absolute amount of Na, higher Na density was associated with higher SBP and DBP (both p<0.0001) in the control diet arm (Figure 1). At the recommended upper limit of Na (2300 mg), the average SBP and DBP of those on a medium-Na-density diet was 7.2 mmHg (95% CI: 4.8, 9.7) and 3.9 mmHg higher (95% CI: 2.3, 5.5), respectively, than those on a low-Na-density diet. At 3600 mg, the average SBP and DBP of those on a high-Na-density diet was 6.0 mmHg (95% CI: 3.6, 8.5) and 3.1 mmHg (95% CI: 1.5, 4.7) higher, respectively, than those on a medium-Na-density diet. These differences were somewhat smaller, but still significant, in the DASH diet arm.
Conclusions: The effects of Na on BP vary with energy needs. This suggests that Na density should be considered when designing and interpreting studies of Na and BP and when providing dietary guidance.
Author Disclosures: M.A. Murtaugh: None. L.J. Appel: None. J.M. Beasley: None. P.M. Guenther: None. T. Greene: None. M.L. McFadden: None. J.A. Tooze: None.
- © 2017 by American Heart Association, Inc.