Salt-sensitive phenotypes: A community-based exploratory study from northeastern India

Background: Salt sensitivity is known to increase the risk of cardiovascular diseases in both normotensive and hypertensive subjects. The population in the northeastern region of India consumes excess dietary salt but their saltsensitive phenotype is not known. Methods: We did a community-based exploratory study using volunteers in the northeastern region of India to determine salt-sensitive (SS) and salt-resistant (SR) phenotypes. A total of 374 (206 normotensive and 168 hypertensive) subjects who gave informed consent were stabilized for salt with 7 days of a low-salt (2.9 g/day) diet followed by 7 days of a high-salt (15.2 g/day) diet. SS was defined as an increase of mean arterial blood pressure ≥9 mmHg after a high-salt diet. Results: We noted an increase in systolic blood pressure of 9.3 mmHg in normotensive subjects and 10.7 mmHg in hypertensive subjects, with a modest effect on diastolic blood pressure (6.9 mmHg in normotensive and 8.2 mmHg in hypertensive subjects) after a high-salt diet. Salt-sensitive phenotype was present in 40.8% of normotensive and 47.6% of hypertensive subjects. Resistance to introduction of high salt was observed in 43.7% of normotensive and 33.9% of hypertensive subjects. Consumption of extra salt (adjusted OR 1.99, 95% CI 1.25-3.18) was independently associated with salt sensitivity. Conclusion: Salt sensitivity was found in a large proportion of normotensive and hypertensive subjects. Restriction of salt intake could be an effective intervention to control hypertension among salt-sensitive subjects.