Does Seasonality Matter? Seasonal Variations in Sodium Intake in Arterial Hypertension

Objective: Reduction of sodium intake is a crucial component of non-pharmacological management of arterial hypertension. However, dietary habits can vary depending on the season. The aim of our study was to evaluate seasonal variations in sodium intake among patients with treated arterial hypertension. Design and method: The study included 51 patients with arterial hypertension (33 women and 18 men, mean age 66.5 ± 6.0 years, BMI 28.6 ± 3.7 kg/m2). Each patient was administered a standardised food frequency questionnaire and a 3-day dietary recall. Patients performed a 24-hour urine collection, in which the sodium concentration was determined and 24-hour urinary sodium excretion was calculated. This complete set of tests was collected for each patient in the winter (December–February) and summer (June–August) months. Comparisons between seasons were performed using the paired Student's t-test and the chi-squared test. Results: Sodium intake, as calculated from the dietary recall, was significantly higher in winter than in summer (5490.2 vs. 3763.33 mg/24 h, p < 0.001). However, urinary sodium excretion values from the 24-hour urine collection did not differ between the winter and summer months (178.53 vs 181.79 mmol/24 h, p = 0.76). Based on the three-day dietary recall, it was found that, in winter, none of the patients in the study group met the recommendation of an intake of less than 2000 mg of sodium per 24 hours, whereas in summer, only five patients (9.8%) met this recommendation. Conclusions: Patients with arterial hypertension do not adhere to the recommended sodium intake restriction, regardless of the season. This problem appears to be more pronounced in winter. This may suggest that sodium intake contributes to the seasonal variability of blood pressure.