Table 2.
Summary of included trials reporting the effect of dietary zinc intake on serum/plasma zinc status in children.
| First Author, Year, Country | Participants | Treatment Groups (n) | Mean Zn Intake (mg/day) | Mean (SD) Plasma/Serum Zn (µmol/L) | Duration | Zinc Status Biomarker [Analytical Method] | Main Results |
|---|---|---|---|---|---|---|---|
| Mahloudji, 1975, Iran [23] | Males & females | Fe only (12); | 5.65; | 8.95 (1.80) | 8 months | Plasma Zn [AAS] | No significant difference between plasma Zn of the supplemented and placebo groups |
| aged 6–12 years | Fe + 20 mg/day Zn (13) | 25.65 | 8.50 (1.93) | ||||
| Hambidge, 1979, USA [24] | Males & females | Male placebo (15); | 6.3; | 11.06 (2.23) | 9 months | Plasma Zn [AES] | Plasma Zn significantly higher in Zn supplemented compared to placebo (girls and combined sexes only p < 0.05) |
| aged 33–90 months | Male Zn FM 2.57 mg/day (20); | 9.27; | 11.85 (2.23) | ||||
| Female placebo (14); | 6.3; | 10.61 (1.81) | |||||
| Female Zn FM 2.57 mg/day (11) | 9.27 | 11.96 (1.81) | |||||
| Walravens, 1983, USA [25] | Males & females | Placebo (16); | 4.6; | 11.32 (2.14) | 12 months | Plasma Zn [AES] | No significant difference between plasma Zn of the supplemented and placebo groups |
| aged 2–6 years | 10 mg/day Zn (16) | 15.9 | 10.86 (2.14) | ||||
| Gibson, 1989, Canada [26] | Males | Placebo (21); | 6.4; | 15.8 (3.5) | 6 months | Serum Zn [AAS] | No significant correlation between serum Zn and dietary Zn levels |
| aged 59–95 months | 10 mg Zn/day (18) | 16.7 | 17.9 (3.4) | ||||
| Cavan, 1993, Guatemala [27] | Males & females, | Placebo (74); | 5.65; | 14.9 (2.1) | 25 weeks | Plasma Zn [AAS] | Plasma Zn significantly higher in Zn supplemented compared to placebo ( p < 0.01) |
| mean age 81.5 (±7.0) months 1 | 10 mg Zn/day (71) | 15.65 | 16.2 (2.9) | ||||
| Friis, 1997, Zimbabwe [28] | Males and females | Placebo (121); | 5.65; | 10.89 (2.5) | 12 months | Serum Zn [AAS] | The decline in zinc concentration was significantly lower in the Zn supplemented group compared to the placebo group ( p < 0.02) |
| aged 11–17 years | 30–50 mg/day Zn (122) | 45.65 2 | 11.71 (2.4) | ||||
| Rosado, 1997, Mexico [29] | Males & females | Placebo (55); | 5.65; | 14.4 (4.45) | 12 months | Plasma Zn [AAS] | Plasma Zn increased significantly in the Zn supplemented group over the 12 months period (p < 0.01) |
| aged 18–36 months | 20 mg Zn/day (54) | 25.65 | 16.8 (5.88) | ||||
| Ruz, 1997, Chile [30] | Males & females | Placebo (33); | 6.4; | 17.7 (1.9) | 6 months | Plasma Zn [AAS] | No significant difference between plasma Zn of the supplemented and placebo groups |
| aged 27–50 months | 10 mg/day Zn (36) | 17.1 | 17.6 (2.2) | ||||
| Sandstead, 1998, China [31] (3 regions) | Males & females | Chonqing MN, no Zn (35); | 5.65; | 19.83 (4.12) | 10 weeks | Plasma Zn [AAS] | Plasma Zn significantly higher in Zn supplemented compared to placebo (p < 0.05) in Chonqing and Quindgdao groups. |
| aged 6–9 years | 20 mg/day Zn + MN (35); | 25.65; | 23.6 (4.12) | ||||
| Quindgdao MN, no Zn (36); | 5.65; | 20.42 (4.08) | |||||
| 20mg/day Zn + MN (36); | 25.65; | 22.97 (4.08) | |||||
| Shanghai MN, no Zn (37); | 5.65; | 17.9 (2.75) | |||||
| 20 mg/day Zn + MN (37) | 25.65 | 17.97 (2.75) | |||||
| Clark, 1999, UK [32] | Peripubertal females, | Placebo (19); | 6.6; | 12.6 (1.0) | 6 weeks | Serum Zn [no method given] | Serum Zn significantly higher in Zn supplemented compared to placebo ( p < 0.001) |
| mean age 12.2 (±0.3) years | 15 mg Zn/day (23) | 21.6 | 16.7 (4.9) | ||||
| Smith, 1999, Belize [33] | Males & females | Placebo (10); | 5.65; | 11.7 (0.68) | 6 months | Serum Zn [AAS] | Serum Zn significantly higher in Zn supplemented compared to placebo (p < 0.001) |
| aged 22–66 months | 70 mg Zn/day (12) | 75.65 | 13.5 (0.68) | ||||
| Munoz, 2000, Mexico [34] | Males & females | Placebo (54); | 5.65; | 14.3 (4.7) | 6 months | Plasma Zn [AAS] | Serum Zn significantly higher in Zn supplemented compared to placebo (p < 0.0001) |
| aged 18–36 months | 20 mg/day Zn (47) | 25.65 | 16.8 (5.6) | ||||
| Lopez de Romana, 2005, Peru [35] | Males & females | Fe FM (12); | 4.71; | 11.87 (1.88) | 70 days | Plasma Zn [ICP-MS] | No significant differences in plasma Zn were found between treatments |
| aged 3–4 years | Fe + 3 mg/day Zn FM (10); | 8.72; | 11.65 (1.25) | ||||
| Fe + 9 mg/day Zn FM (12); | 15.7 | 12.60 (1.51) | |||||
| Silva, 2006, Brazil [36] | Males & females aged 12–59 months 3 | Placebo (30); 10 mg/day Zn (28) | 5.65; 15.65 | 8.0 (0.58)13.4 (0.25) | 4 months | Serum Zn [AAS] | Serum Zn significantly higher in Zn supplemented compared to placebo (p < 0.05) |
| Sandstead, 2008, USA (Mexican Americans) [37] | Males & females | MN, no Zn (25); | 5.65; | 15.4 (1.5) | 10 weeks | Plasma Zn [AAS] | Mean plasma Zn increased significantly in both groups compared to baseline (p < 0.05) |
| aged 6–7 years | 20 mg/day Zn + MN (25) | 25.65 | 15.6 (1.2) | ||||
| Wuehler, 2008, Ecuador [38] | Males & females | Placebo (56); | 5.65; | 10.6 (1.6) | 6 months | Plasma Zn [ICP-MS] | The mean change in plasma zinc concentrations from baseline increased progressively with higher doses of supplemental Zn (p < 0.001) |
| aged 12–30 months | 3 mg Zn/day (50); | 8.65; | 12.3 (1.6) | ||||
| 7 mg Zn/day (52); | 12.65; | 13.3 (1.7) | |||||
| 10 mg Zn/day (54) | 15.65 | 14.0 (1.7) 4 | |||||
| de Oliveira, 2009, Brazil [39] | Pubescent males, | Placebo (26); | 5.65; | 16.9 (2.1) | 12 weeks | Plasma Zn [ICP-MS] | Plasma Zn significantly higher in Zn supplemented compared to placebo (p < 0.05) |
| mean age 13 (±0.4) years | 22 mg Zn/day (21) | 27.65 | 18.7 (3.5) | ||||
| Uckarde, 2009, Turkey [40] | Males & females | Placebo (109); | 5.65; | 19.19 (1.80) | 10 weeks | Serum Zn [CS] | Both supplemented and placebo groups had significantly higher serum Zn at follow up (p < 0.05) |
| aged 8–9 years | 15 mg/day Zn (109) | 20.65 | 19.50 (2.41) |
AAS, atomic absorption spectroscopy; AES, atomic emission spectroscopy; ICP-MS, inductively coupled plasma mass spectrometry; CS, caloric spectrophotometry; MN, micronutrients; FM, fortified meal; 1 all participants also received MN supplements; 2 children weighing <29.5 kg were given 30 mg Zn/day and those >29.5 kg were given 50 mg Zn/day, this figure is an average of the two doses; 3 all participants also received Fe fortified milk; 4 geometric means.