Evaluation of Salt Intake Levels and Related Factors in Individuals who Underwent a Specific Health Examination: The LIFE Study.

INTRODUCTION

High salt intake has been linked to various diseases. However, measuring an individual's salt intake level may be challenging. This study aimed to identify the characteristics of individuals with high salt intake using a salt intake check sheet.

METHODS

This is a cross-sectional study that used data from the Longevity Improvement & Fair Evidence (LIFE) Study. Participants were individuals who underwent a specific medical examination between April 2023 and March 2024 and also completed a salt intake check sheet. Individuals with missing data from the health examinations or the salt intake check sheet were excluded from the study. Individuals taking antihypertensives were also excluded.Exposure factors were defined as participant sex, age range (40-64 and 65-74 years old), smoking, alcohol consumption, regular exercise, body mass index (BMI; <25 kg/m2 or ≥25 kg/m2), and the presence of hypertension during specific health examinations (systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg). The salt intake level of participants, based on scores from the salt intake check sheet, was evaluated as the outcome in this study. Using these scores, participants were categorized into two groups: the low salt intake group (0-13 points) and the high salt intake group (>14 points). To evaluate the factors related to salt intake, the salt intake levels (high or low) of participants were set as the response variable, while the exposure factors were set as the explanatory variables. Modified Poisson regression analysis was then conducted.

RESULTS

This study comprised 5,157 participants, with 3,745 in the low salt intake group (72.6%) and 1,412 in the high salt intake group (27.4%). Results from the modified Poisson regression analysis conducted to evaluate the correlation between individual salt intake levels and exposure factors showed statistically significant correlations between the following factors and high salt intake: smoking (relative risk [RR] = 1.35, 95% confidence interval [CI]: 1.21-1.50, p < 0.001); alcohol consumption (RR = 1.19, 95% CI: 1.09-1.30, p < 0.001); and BMI >25 kg/m2 (RR = 1.32, 95% CI: 1.19-1.47, p < 0.001). Conversely, participants in the low salt intake group were at lower risk for hypertension compared to those in the high salt intake group; however, the difference was not statistically significant (RR = 0.92, 95% CI: 0.85-1.01, p = 0.08).

CONCLUSIONS

The results of this study showed that smoking, alcohol consumption, and having a BMI of ≥25 kg/m2 were related to high salt intake.