Table 1.
Characteristics of included studies.
| Study Name | n | Population | Dose & type of oral iron | Baseline Iron Status | Study duratn, Drop-outs | Cognitive tests* |
|---|---|---|---|---|---|---|
| Beard 2005 [19,45] | Iron 34 Pl 30 |
S Africa-mothers, 18-30 yrs Pre-menopausal women |
125 mg/d as pills | Anaemic - Hb 9-11.5 g/dl, SF 10-12 μg/L | 29 wks, Iron 2 Pl 4 |
Raven's CPM (IQ), Wechsler's DS (M, Ps) |
| Bruner 1996 [30,46] | Iron 40 Pl 41 |
USA-adolescents, school, mean age 16.2 and 15.7 Children 6-18 |
260 mg/d EFe as capsules | Iron Defic - Hb>11.5 g/dl (Af American), Hb>12 g/dl (white), SF<12 μg/L for all | 8 wks, Iron 1 Pl 2 |
Visual Search and Attention (AC), Hopkin's Verbal Learning Test (M), DS Modalities (Ps), Attention. |
| Elwood 1970 [20] | Iron 26 Pl 21 |
UK - women >20 yrs Pre-menopausal women |
150 mg/d as tablets | Anaemic - HB<10.5 g/dl | 8 wks, Iron 0 Pl 0 |
Mazes test (AC), Serial Sevens (M), Peg board (Ps), E test, card sorter. |
| Gopaldas 1985 [21,47-49] | Iron 32 Pl 16 |
India-School boys-recipients of free noon meal, 8-15 yrs Children 6-18 |
30 or 40 mg/d as tablets | Anaemic - Hb<10.5 g/dl, Iron Defic and/or Repl- rest | 8.5 wks, Iron 0 Pl 0 |
Mazes test (AC), Visual Memory Test (M), Wechsler's Digit span (Ps), Clerical task |
| Groner 1986 [22] | Iron 19 Pl 19 |
USA-pregnant women, 14-24 yrs Pre-menopausal women |
60 mg/d EFe as capsules | Iron repl - mean Hb>12 g/dl, SF 40-60 μg/L | 4 wks, Iron 3 Pl 10 |
Vocab (IQ), DS (M, Ps), Arithmetic (SA), Consonant trigram, Rey AVL, Digit Span |
| Kashyup 1987 [23,49] | Iron 83 Pl 83 |
India-School girls, under privileged, 8-15 yrs Children 6-18 |
60 mg/d EFe as tablets | Anaemic - Hb<10.5 g/dl, Iron Defic and/or Repl-rest | 17.2 wks, Iron 18 Pl 18 |
Mazes test (AC), Visual Memory (M), Wechsler's Digit span (Ps), Clerical |
| Kordas 2005 [32,50,51] | Iron 303 Pl 299 |
Mexico-school children, mean age 7.0 Children 6-18 |
30 mg/d as tablets | Iron Defic and/or Repl - Hb>9 g/dl | 21 wks, Iron 38 Pl 49 |
Distractibility (AC), Peabody PV (IQ), Vis Memory (M), Maths (SA), Sternberg** |
| Lambert et al., 2002 [27] | Iron 57 Pl 59 |
New Zealand-female high school students, 12.5-17.9 yrs Children 6-18 |
105 mg/d EFe as tablets | Iron defic - Hb>12 g/dl, SF<12 μg/L | 8 wks, 5 across whole study |
Visual Search and Attention (AC), Hopkin's Verbal Learning (M), Stroop task, Reading span |
| Lynn & Harland 1998 [15] | Iron 208 Pl 205 |
England - teenagers at 7 comprehensive schools, 12-16 yrs Children 6-18 |
17 mg/d EFe as tablets | Iron Defic - any Hb, SF<12 μg/L ??and??? Iron Repl - the rest | 16 wks, Unclear, ~200 over study? |
Raven's CPM (IQ) |
| Murray-Kolb et al 2007 [31] | Iron 76 Pl 76 |
USA-Women, aged 18-35 yrs Pre-menopausal women |
60 mg/d EFe as pills | Anaemic - Hb 10.5-11.9 g/dl plus 2 aFeSIs, Iron Defic - Hb = 12 g/dl plus 2 aFeSIs, Iron Repl - Hb = 12 g/dl without 2 aFeSIs | 16 wks, Iron 20 Pl 19 |
Cog Abilities-attention (AC), Cog Abilities - memory (M), Cog Abilities - learning (SA), Shipley Inst Scale (IQ) |
| Pollitt 1989 [24] | Iron 678 Pl 678 |
Thailand-school children, 9-12 yrs Children 6-18 |
4 mg/kg/d EFe as tablets | Anaemic Hb<12 g/dl and SF<10 μg/L or TS<16%, Iron Defic Hb>12 g/dl and SF<10 μg/L or TS<16%, Iron Repl - rest | 16 wks, Not reported |
Raven's CPM (IQ), Mathematics (SA), Thai language |
| Soemantri 1985 [29,52] | Iron 59 Pl 60 |
Indonesia-primary school children, mean age 10.7 to 11.1 yrs Children 6-18 |
2 mg/kg/d EFe as tablets | Anaemic - Hb<11 g/dl, TS<15%, Iron Repl - Hb>12 g/dl, TS>20% | 13 wks, Iron 0 Pl 0 |
Raven's CPM (IQ), Bourden-wisconsin concentration, Maths, Language, Biology, social science |
| Soemantri 1989 [25] | Iron 71 Pl 59 |
Indonesia-primary school children, mean age 10.4 Children 6-18 |
2 mg/kg/d EFe tablets | Anaemic - Hb<11 g/dl, TS<12%, Iron Repl - Hb>12 g/dl. TS <20% | 13 wks, Iron 0 Pl 0 |
Raven's CPM (IQ), Maths (SA), Language, Biology, social science |
| Sungthong 2004 [26,53] | Iron/d 112 Iron/wk 102 Pl 99 |
Thailand-School children, mean age 9.6 to 9.7 Children 6-18 |
60 mg/d or/wk EFe, tablets | Iron Repl - Hb>8 g/dl, SF>20 μg/L | 16 wks, Iron/d 1 Iron/wk 4 Pl 1 |
Test of Non-Verbal Intelligence (IQ), Maths (SA), Thai Language |
*tests in bold have been used in the analysis
** Plus Figure match & design, Stimulus discrimination, Cognitive abilities, Visual search, Sequencing
Hb: haemoglobin, TS: transferrin saturation, SF: serum ferritin, EFe: elemental iron, aFeSI: abnormal iron status indicators, Pl: placebo, AC: Attention and concentration, IQ: Intelligence quotient, M: memory, Ps: psychomotor, SA: Scholastic Achievement, Raven's CPM: Raven's Colour Progressive Matrices, Peabody PV: Peabody Picture Vocabulary, Rey AVL: Rey Auditory Verbal Learning, Digit Symbol: DS, Repl: repletion, Defic: deficient