[Correlations between dietary salt intake and 24-h urine sodium excretion in a sample of the urban population of Cáceres]. / Correlaciones entre la ingesta de sal en la dieta y la eliminación de sodio en la orina de 24 h en una muestra de población urbana de Cáceres.

OBJECTIVE: Excessive salt intake is associated with higher levels of AHT and prevalence of cardiovascular diseases. WHO recommends consuming less than 5 g/day of salt (equivalent to 2 g Na+/day). Identifying foods and behaviours with greater contribution to excess intake would facilitate preventive dietary advice. DESIGN: Observational study. SITE: Urban Health Center in Cáceres. MAIN MEASUREMENTS: We estimated salt consumption using two food consumption frequency (FFQ) questionnaires, one generic and one with high Na+ content, and a 24 h follow-up survey. We use the Evalfinut program for nutritional evaluation of the diet. We analyzed correlations between estimated salt intake and 24-h urine sodium elimination (gold standard). RESULTS: 92% of the population had consumption higher than the recommendations with intakes equivalent to 9.5 g/day of salt (3.7 g/d of Na+). When sodium intake is determined by the Na+/K+ ratio, 79.54% have high intakes. Sodium elimination follows a slightly increasing trend with BMI. The perception of salt consumption is low, 56.3% consider it "adequate". 32.4% add salt to food once served. FFQ underestimate Na+ intake and targeted surveys provide higher values. The correlation between FFQ and Na+ urinary elimination is weak. CONCLUSION: We must reduce salt intake by increasing the perception of consumption, improving knowledge about the salt content in food and identifying target patients of the health council.

[Validity and limitations of methods to measure the intake and elimination of salt]. / Validez y limitaciones de los métodos para medir la ingesta y la eliminación de sal.

High blood pressure (HBP) is the main modifiable cardiovascular risk factor. HBP can be related to high salt intake. To measure intake, not all feeding surveys are comparable and valid. The reference procedure for assessing salt intake consists of measuring the urinary excretion of sodium in urine collected during 24hours, although alternative methods have been proposed, such as the collection of punctual and timed urine samples. In this review, we analyze which instruments allow the assessment of salt intake and which of them have provided greater validity and reliability through studies of concordance with the elimination of sodium in urine. Current food consumption surveys are inadequate because of their wide variability and relatively low correlation with the elimination of sodium in 24-hour urine. Its main limitation is the need for validation in different population groups. In primary care, salt intake should be assessed by using frequency-of-consumption questionnaires that collect foods with a high salt content, the consumption of preprepared dishes and questions that quantify the addition of salt in the preparation of food or at the table. For the validation of these questionnaires, the standard gold elimination of 24-hour urine sodium adjusted according to creatinine clearance should be used.

Design of a Nutritional Survey to Detect High Dietary Salt Intakes and Its Usefulness in Primary Care Compared to 24-Hour Urine Sodium Determination.

Many population studies report salt intakes that exceed the WHO recommendation (2 g/day of Na+ or 5 g/day of salt). We do not have tools for detecting high salt intakes that are easy to apply in primary health care (PHC). We propose the development of a survey to screen for high salt intake in PHC patients. A cross-sectional study of 176 patients determines the responsible foods, and a study of 61 patients studies the optimal cut-off point and discriminant ability (ROC curve). We assessed the salt intake using a food frequency questionnaire and a 24 h dietary recall and used a factor analysis to identify the foods with the highest contribution to be included in a high intake screening questionnaire. We used 24 h urinary sodium as a gold standard. We identified 38 foods and 14 factors representing a high intake, explaining a significant proportion of the total variance (50.3%). Significant correlations (r > 0.4) were obtained between nutritional survey scores and urinary sodium excretion, allowing us to detect patients who exceed salt intake recommendations. For sodium excretion ≥ 2.4 g/day, the survey has a sensitivity of 91.4%, a specificity of 96.2% and an area under the curve of 0.94. For a prevalence of high consumption of 57.4%, the positive predictive value (PPV) was 96.9% and the negative predictive value (NPV) was 89.2%. We developed a screening survey for subjects with a high probability of high salt intake in primary health care, which could contribute to the reduction in diseases associated with this consumption.