Blood pressure responses to dietary sodium and potassium interventions and the cold pressor test: the GenSalt replication study in rural North China

Abstract

Background: In the Genetic Epidemiology Network of Salt Sensitivity (GenSalt) study, we observed that blood pressure (BP) responses to dietary sodium and potassium interventions and the cold pressor test (CPT) varied greatly among individuals. We conducted a replication study to confirm our previous findings among 695 study participants.

Methods: The dietary intervention included a 7-day low sodium (51.3 mmol/day), a 7-day high sodium (307.8 mmol/day), and a 7-day high sodium with potassium supplementation (307.8 mmol sodium and 60 mmol potassium/day). BP measurements were obtained during the baseline and each intervention phase. During the CPT, BP was measured before and at 0, 1, 2, and 4 minutes after the participants immersed their right hand in ice water for 1 minute.

Results: Systolic and diastolic BP responses (mean ± SD (range), mm Hg) were 8.1±8.4 (-39.1 to 18.2) and -3.5±5.1 (-25.1 to 11.1) to low sodium, 9.1±8.4 (-13.3 to 33.1) and 4.0±5.4 (-16.0 to 20.7) to high sodium, and -4.6±5.8 (-31.8 to 11.6) and -1.9±4.3 (-16.9 to 14.2) to potassium supplementation, respectively (all P < 0.0001 for comparison with each former phase). The mean maximum systolic and diastolic BP responses to the CPT were 16.5±10.5 (-15.3 to 63.3) and 7.6±6.1 (-8.7 to 39.3), respectively (all P < 0.0001).

Conclusions: Our study indicates that there are large variations in BP responses to dietary sodium and potassium interventions and to the CPT among individuals.

Trial registration: ClinicalTrials.gov NCT00721721.

Keywords: blood pressure; cold pressor test; dietary potassium; hypertension; salt sensitivity; sodium..

Figures

Figure 1.

Distribution of systolic blood pressure (SBP) (upper panel, a–c) and diastolic blood pressure (DBP) (lower panel, d–f) responses to low-salt intervention (left panel), high-salt intervention (middle panel), and potassium supplementation (right panel). Black bars indicate individuals with zero blood pressure (BP) response. BP response to low salt = BP on low-salt diet – BP at baseline; BP response to high salt = BP on high-salt diet – BP on low-salt diet; and BP response to potassium supplementation = BP on high-salt diet with potassium supplementation – BP on high-salt diet.

Figure 2.

Distribution of systolic blood pressure (SBP) (upper panel, a–d) and diastolic blood pressure (DBP) (lower panel, e–h) responses to the cold pressor test (CPT) at 0, 1, 2, and 4 minutes after the end of ice-water immersion. Black bars indicate individuals with zero blood pressure (BP) response. BP response at 0 minutes = BP at 0 minutes – pre-CPT BP; BP response at 1 minute = BP at 1 minute – pre-CPT BP; BP response at 2 minutes = BP at 2 minutes – pre-CPT BP; and BP response at 4 minutes = BP at 4 minutes – pre-CPT BP.