Contemporary Dietary Intake: Too Much Sodium, Not Enough Potassium, yet Sufficient Iodine: The SALMEX Cohort Results

Abstract

Initiatives to reduce sodium intake are encouraged globally, yet there is concern about compromised iodine intake supplied through salt. The aim of the present study was to determine baseline sodium, potassium, and iodine intake in a sample of workers from our Institution in Mexico City (SALMEX Cohort). Methods. From a cohort of 1009 workers, appropriate 24-h urine and three-day dietary recall was collected in a sample of 727 adult subjects for assessment of urinary sodium, potassium, and iodine concentrations. Median urinary iodine excretion (UIE) was compared across categories of sodium intake of <2, 2⁻3.6, and &ge;3.6 g/day. Results. Average sodium intake was 3.49 ± 1.38 g/day; higher in men than women (4.14 vs. 3.11 g/day, p &le;0.001). Only 10.6% of the population had sodium intake within the recommended range (<2 g/day); 45.4% had high (2⁻3.6 g/day) and 44% had excessive intake (>3.6 g/day). Average urinary Na/K ratio was 3.15 ± 1.22 (ideal < 1), higher in men (3.42 vs. 3.0, p &le; 0.001). The multivariate analysis showed that sodium intake was associated with age (p = 0.03), male sex (p < 0.001), caloric intake (p = 0.002), UKE (p < 0.001) and BMI (p < 0.001). Median iodine intake was 286.7 &micro;g/day (IQR 215⁻370 &micro;g/day). Less than 2% of subjects had iodine intake lower than recommended for adults (95 &micro;g/day); 1.3% of subjects in the recommended range of salt intake had low iodine intake. There is a direct relationship between iodine and sodium urinary excretion (r = 0.57, p < 0.0001). Conclusions. In the studied population, there was an excessive sodium intake and an imbalance between sodium and potassium intake. Only 10.6% of the population had sodium intake within the recommended values, but iodine intake in this group appears to be adequate.

Keywords: iodine intake; salt intake; sodium-potassium ratio.

Figure 1

Deciles of sodium intake. The percentage of subjects with sodium intake ≤2 g/day for men 3.8% and women 14.3%, median sodium intake for men (4.2 g/day) and women (3.0 g/day).

Figure 2

Distribution of iodine intake according to urinary iodine excretion. The green line represents the total sample, men are represented in blue and women in red. A. Blue dotted lines represent the estimated average requirement of iodine (EAR = 95 µg/day); only 8 women and one man had less than this value. B. Red dotted lines represent the recommended daily allowance of iodine (RDA = 150 µg/day); 70 subjects (9.6%) had less than this value. C. Gray dotted lines represent the minimum intake allowance for adult women (180 µg/day); 101 women (14%) had less than this value. D. Black lines represent the maximum intake recommended for adult women (500 µg/day); only 17 women (2.3%) had more than this value. There were no subjects with UIE >1000 µg/day.