Dietary salt intake and hypertension in an urban south Indian population--[CURES - 53]

Abstract

Objective: The aim of the study was to determine the mean dietary salt intake in urban south India and to look at its association with hypertension.

Methods: The Chennai Urban Rural Epidemiology Study (CURES) is an ongoing population based study on a representative population of Chennai city in southern India. Phase 1 of CURES recruited 26,001 individuals aged > or = 20 years, of whom every tenth subject (n = 2600) was invited to participate in Phase 3 for detailed dietary studies and 2220 subjects participated in the present study (response rate: 84.5%). Participants with self-reported history of hypertension, diabetes or heart disease were excluded from the study (n = 318) and thus the final study numbers were 1902 subjects. Dietary salt, energy, macronutrients and micronutrients intake were measured using a validated semi-quantitative food frequency questionnaire. Diagnosis of hypertension was based on the National Cholesterol Education Programme (NCEP) Adult Treatment Panel III criteria. Logistic regression analysis was used to look at the association of dietary salt with hypertension.

Results: Mean dietary salt intake (8.5 g/d) in the population was higher than the recommended by the World Health Organization (< 5g/d). Higher salt intake was associated with older age and higher income (p for trend < 0.0001). Subjects in the highest quintile of salt intake had significantly higher prevalence of hypertension than did those in the lowest quintile (48.4 vs 16.6%, p < 0.0001). Both systolic and diastolic blood pressure significantly increased with increase in quintiles of total dietary salt both among hypertensive and normotensive subjects (p for trend p < 0.0001). Addition of salt > 1 teaspoon/day at the dining table was associated with a higher prevalence for hypertension compared to zero added salt (38.5% vs 23.3%, Chi-square = 18.95; p < 0.0001). Multiple logistic regression analysis revealed that even after adjusting for age, gender, body mass index, total energy intake and dietary fat, total dietary salt intake was positively associated with hypertension. [Odds ratio (OR): 1.161, 95% Confidence Interval (CI): 1.115-1.209, p < 0.0001].

Conclusion: Intake of dietary salt in urban south India is higher than currently recommended. Increasing salt intake is associated with increased risk for hypertension even after adjusting for potential confounders. This calls for urgent steps to decrease salt consumption of the population at high risk.