Abstract
(Englisch)
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Salt is a mainstay of most modern diets. Excessive dietary salt may be implicated in the etiology of hypertension and cardiovascular diseases (CVD). To answer the question if Swiss everyday salt intakes are excessive and would justify a national public health intervention to reduce dietary salt, we present here the case of Geneva, Switzerland.
Analyses are based on data from continuous surveillance of the general adult (35-74 yrs) population of Geneva, Switzerland for 10 years (1993-2002) using a locally-validated, semi-quantitative food frequency questionnaire. Independent, cross-sectional surveys of representative samples (5,536 men, 5,471 women). Salt intake (excluding discretionary salt) derived from sodium composition of foods. Dietary salt (sodium chloride, NaCl) intake and density are described by gender, trends therein, and their associations with socio- and health-behavioral risk factors for CVD.
Quartiles of salt intake from foods (g/d) were 4.4, 6.0, 7.9 in men, and 3.6, 4.9, 6.5 in women. Quartiles of salt density (g/MJ/d) were 0.57, 0.66, 0.76 in men, and 0.59, 0.69, 0.80 in women. Both measures were extremely stable during the 10-year surveillance period, regardless of hypertension treatment. Breads (men/women: 28%/28%), cheeses (19%/15%), soups (9%/12%), ready-to-eat meals (8%/7%), and meat and meat products (13%/10%) were the main sources (76%/72%) of dietary salt from foods. Salt density increased with age decades, Mediterranean origin, and relative weight groups, but there was a negative association with alcohol intake.
Men have higher dietary salt intakes but lower dietary salt densities than women, with no evidence of 10-year trends in either measure by gender. Breads, cheeses, soups and other convenience-type foods, meat and meat products are major sources of dietary salt. Main determinants of dietary salt density are age, birthplace, relative weight, and alcohol intake. Salt density differences between CVD risk factor subgroups are moderate. Overall, assuming an additional 2-3 g/d of discretionary salt, total salt intakes in Geneva are above current recommendations.
There is a well-documented, weak association between salt intake and blood pressure. Several grams difference in salt intake can reduce the average systolic and diastolic blood pressure by a maximum of 5 to 10 mmHg. It is also well established that the association tends to be restricted to subgroups of the population whose variation in blood pressure is particularly sensitive to salt intake. Surveys in relatively homogeneous populations are therefore unlikely to be able to detect strong associations between salt and hypertension, overall. In this study we have addressed two questions of great public health relevance: (1) Are there differences in consumption of salt-rich foods between normotensive and hypertensive subjects and, (2) are there interactions of salt intake with age and other biologic or behavioral characteristics with respect to hypertension status in large population-based samples?
Continuous surveillance of the general adult (35-74 yrs) population of Geneva, Switzerland for 10 years (1993-2002) using independent, cross-sectional surveys of representative samples (5,536 men, 5,471 women). Locally-validated, semi-quantitative food frequency questionnaire. Salt intake (excluding discretionary salt) derived from sodium composition of foods. Systolic and diastolic blood pressures is measured once in the sitting position with cuff placed on the right arm.
There is a weak association between total dietary salt density and severe hypertension in men only. The adjusted regression model estimates that a 10 to 20% change in salt density can reduce systolic blood pressure by 1 mmHg. This is consistent with the literature, but too small to be accurately assessed in our study. There were no substantial differences in food sources of salt intake between normotensive and hypertensive subjects. The relation between salt and blood pressure/hypertension was consistently weak or absent across age groups or across alcohol intake groups. No specific salty food item appears to distinguish the diet of normotensive and hypertensive people.
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