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. Author manuscript; available in PMC: 2019 Feb 1.
Published in final edited form as: Environ Int. 2017 Nov 21;111:43–51. doi: 10.1016/j.envint.2017.11.013

Table 2.

Associations among the intakes of micronutrients (iron, zinc, calcium, vitamin C and folate), and biomarkers of lead exposure among school-age children from Montevideo, Uruguay.

Nutrient intake (mg or μg/1000 kcal/day) Blood lead concentration
ß [95% CI]		 Urinary lead concentration1
ß [95% CI]
Unadjusted Covariate-adjusted2 Unadjusted Covariate-adjusted2
Iron (Fe)
 Low (1.98 – 3.91) Ref. Ref Ref. Ref.
 Medium (3.92 – 4.88) 0.22 [−0.36, 0.80] 0.43 [−0.16, 1.03] 0.01 [−0.17, 0.20] −0.05 [−0.26, 0.15]
 High (4.89 – 49.38) −0.21 [−0.80, 0.37] −0.05 [−0.66, 0.56] −0.11 [−0.29, 0.08] −0.10 [−0.31, 0.11]
p-value for trend test 0.47 0.87 0.26 0.34
Zinc (Zn)
 Low (0.48 – 1.79) Ref. Ref. Ref. Ref.
 Medium (1.81 – 2.75) −0.39 [−0.96, 0.19] −0.39 [−0.98, 0.20] −0.01 [−0.20, 0.17] 0.10 [−0.19, 0.21]
 High (2.77 – 6.91) −0.63 [−1.21, −0.06]** −0.50 [−1.10, 0.10] −0.14 [−0.32, 0.04] −0.18 [−0.38, 0.03]*
p-value for trend test 0.03 0.10 0.13 0.09
Calcium (Ca)
 Low (50.68 – 275.50) Ref. Ref. Ref. Ref.
 Medium (276.10– 383.95) −0.23 [−0.81, 0.34] −0.42 [−1.01, 0.17] −0.09 [−0.27, 0.07] −0.14 [−0.34, 0.06]
 High (384.16– 811.84) −0.48 [−1.06, 0.10] −0.51 [−1.11, 0.09]* −0.32 [−0.50, −0.13]** −0.31 [−0.52, −0.10]**
p-value for trend test 0.10 0.09 <0.01 <0.01
Vitamin C
 Low (0 – 13.11) Ref. Ref. Ref. Ref.
 Medium (13.24 – 24.66) 0.51 [−0.07, 1.08]* 0.53 [−0.08, 1.14]* 0.07 [−0.11, 0.26] 0.10 [−0.11, 0.31]
 High (24.85 – 137.34) 0.43 [−0.15, 1.01] 0.36 [−0.24, 0.97] 0.01 [−0.18, 0.19] 0.07 [−0.14, 0.28]
p-value for trend test 0.14 0.25 0.95 0.53
Folate
 Low (75.03 – 189.37) Ref. Ref. Ref. Ref.
 Medium (189.78 – 247.49) 0.18 [−0.40, 0.77] 0.50 [−0.12, 1.13] 0.06 [−0.13, 0.24] 0.12 [−0.09, 0.34]
 High (249.33 – 466.51) 0.05 [−0.53, 0.63] 0.19 [−0.42, 0.80] 0.09 [−0.10, 0.27] 0.13 [−0.08, 034]
p-value for trend test 0.87 0.61 0.36 0.26
1

Urinary lead concentration adjusted for specific gravity of urine to account for individual variability in hydration levels and subsequently log-transformed;

2

Models adjusted for child sex, age, BMI, serum ferritin concentration, laboratory method for lead analysis (flame vs. graphite atomic absorption spectrometry), parental smoking status, crowding in the home, parental occupation with potential exposure to metals, maternal education level, maternal occupation, household possessions score, and season of recall.