Table 3. Stud ies reporting on the relationship between obesity and iron deficiency (n = 10).
| Author and publication year | Study design | Country | Sample size (n) | Age range or mean age | Obesity definition | Outcome definition | Outcome identification | Covariates | Results | Study quality (based on NOS score) |
|---|---|---|---|---|---|---|---|---|---|---|
| Abd-El Wahed et al. | Case control | Egypt | 120 (62 girls) | 9.25 years | CDC growth charts | The presence of two or more of the following abnormal parameters: Mean corpuscular volume (MCV) is 76 fl or less; serum TS 15% or less; Serum ferritin less than 10 mg ml−1 | Blood sample/assay | Age, sex | Obese status increased odds of iron deficiency (OR 7.09; 95% CI 3.16–15.92) | Low risk of bias (8/8) |
| Brotanek et al. | Cross-sectional | United States | 960 (434 girls) | 1–3 years | Weight-for-length status of ≥95th percentile | Ages 1–2 years, iron deficiency <10% transferrin saturation < 10 g L−1 of serum ferritin and >1.42 mol L−1 of red blood cells erythrocyte protoporphyrin. For 3-year-old children, <12% < 10 g L−1, and >1.24 mol L−1 of red blood cells | Blood sample/assay | Race/ethnicity, interview language, preschool/day care attendance | Obese status increased odds of iron deficiency (OR 3.34; 95% CI 1.10–10.12) | Low risk of bias (8/8) |
| Cepeda-Lopez et al. | Cross-sectional | Mexico | 1174 (49% girls) | 8.17 years | WHO growth reference charts | Either (1) low serum iron (<60 ug dl−1) or (2) elevated TIBC (>360 ug dl−1)and low %TS (<20%) values | Blood sample/assay | Age, sex, region, area, caregiver education | Obese status increased the odds of iron deficiency (OR 3.96; 95% CI 1.34–11.67) | Low risk of bias (7/8) |
| Skinner et al. | Cross-sectional | United States | 2792 | 3–5 years | CDC growth charts | Taking medication for anaemia and laboratory values of hemoglobin <11 g dl−1.16 | Blood sample/assay | Age, ethnicity, income, insurance status | Obese status increased the odds of anaemia in boys but not in girls (boys OR 3.51; 95% CI 1.06–11.91; girls OR 1.02; 95% CI 0.35–2.98) | Low risk of bias (8/8) |
| Crivelli et al. | Cross-sectional | Tajikistan | 1320 (653 girls) | 2–5 years | WHO growth reference charts | WHO cut-off value for iron deficiency in children (Hb < 11 g dl−1) | Finger prick test using Drabkin’s reagent for Hb analysis | Age, sex, location, parental education, region | Obese status did not increase odds of iron deficiency in boys or girls (boys: OR 1.05 95% CI 0.55–2.0; girls: OR 0.85 95% CI 0.38–1.86) | Low risk of bias (7/8) |
| Hamza et al. | Case control | Egypt | 100 (42 girls) | 9.8 years | Cole et al. | Fe deficient when 2 or more Fe profile values were abnormal for age and gender: serum Fe < 20 μg dl−1, TICB >494 μg dl−1, ferritin <12 μg dl−1, TS < 16% (2), and sTfR > 8.3 mg L−1 | Blood sample/assay | Age | Fe, TS and TIBC were significantly lower, while ferritin, sTfR and hepcidin-25 were significantly higher in obese children versus controls | Low risk of bias (8/9) |
| Ibrahim et al. | Case control | Jordan | 150 (61 girls) | 2.1 years | WHO growth reference charts | Internationally accepted cut-off values for biochemical iron markers: Hb (g L−1 = 9.5–14.5; SF (ng ml−1) -29–160; and SI (μg dl−1) - 25–115. | Blood sample/assay | Age | Odds of iron deficiency in obese group compared with normal weight was 3.7 (95% CI 0.9–14.5) | Low risk of bias (6/8) |
| Konstantyner et al. | Cross-sectional | Brazil | 1325 | 1–2 years | WHO growth reference charts | Mild iron deficiency anemia: Hb < 11.0 g dl−1; moderate iron deficiency anemia: Hb < 9.5 g dl−1 | High-performance liquid chromatography (HPLC) of dried blood spot samples | - | Obese status did not increase the odds of mild or moderate anaemia: mild anaemia: OR 1.11 (0.46; 2.64); moderate anemia: 2.41 (0.80; 7.30) | Low risk of bias (7/8) |
| Nead et al. | Cross-sectional | United States | 9698 | 2–16 years | CDC growth charts | Iron-deficient if 2 of 3 values were abnormal for age and gender. Anemia = Hemoglobin cutoff points used to define anemia were based on the fifth percentiles for the reference groups | Blood sample/assay | Age, gender, race/ethnicity, poverty status, caretaker education | Obese status increased the odds of iron deficiency (OR 2.3; 95% CI 1.4–3.9) | Low risk of bias (6/8) |
| Sharif et al. | Case control | Iran | 100 children (49 girls) | 9.5 years | CDC growth charts | Serum iron levels less than 50 μg dl−1 and TIBC higher than 450 μg dl−1 were defined as iron deficiency | Blood sample biochemistry method and plasma ferritin by ELISA method | - | Prevalence of iron deficiency significantly higher in obese versus normal weight children (48% vs. 28%) | Low risk of bias (5/9) |
Abbreviations: BMI, body mass index; CDC, Centers for Disease Control and Prevention; ELISA, enzyme-linked immunosorbent assay; IOTF, International Obesity Task Force; NOS, Newcastle–Ottawa Scale.