Gender difference in blood pressure responses to dietary sodium intervention in the GenSalt study

Objective: To examine factors related to blood pressure (BP) responses to dietary sodium and potassium interventions. Methods: We conducted a dietary feeding study that included a 7-day low-salt intervention (51.3 mmol sodium/day), a 7-day high-salt intervention (307.8 mmol sodium/day), and a 7-day high-salt and potassium-supplementation (60 mmol potassium/day) intervention among 1906 study participants in rural China. The BP was measured nine times during the 3-day baseline observation and during the last 3 days of each intervention phase using a random-zero sphygmomanometer. Results: The BP responses to low-sodium intervention were significantly greater in women than in men: -8.1 [95% confidence interval (-8.6 to -7.6)] versus -7.0 (-7.5 to -6.6) mmHg for systolic and -4.5 (-4.9 to -4.1) versus -3.4 (-3.8 to -3.0) mmHg for diastolic. Likewise, BP responses to high-sodium interventions were significantly greater in women than in men: 6.4 (5.9-6.8) versus 5.2 (4.8-5.7) mmHg for systolic and 3.1 (2.7-3.5) versus 1.7 (1.4-2.1) mmHg for diastolic (all P < 0.001). In addition, systolic BP responses to sodium interventions increased with age, and both systolic and diastolic BP responses to sodium interventions increased with baseline BP levels. BP responses to potassium supplementation also increased with baseline BP levels. Conclusion: These results suggest that female gender, older age, and hypertension increase the sensitivity to dietary sodium intervention. Furthermore, low dietary sodium intake may be more effective in reducing BP among these subgroups.