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Table 5 Summary of results for iodine, Vitamin A and calcium/vitamin D fortification in children

From: Micronutrient fortification of food and its impact on woman and child health: a systematic review

  

Iodine fortification

Outcome/quality of evidence

Combined effect

 

Serum thyroxin levels

SMD: 0.45 (95% CI: -1.15, 2.06)

2 studies 1,131 participants reported this outcome. The studies were conducted in Africa on school-going children.

Quality of evidence: Low

 

Urinary iodine concentrations

SMD: 6.39 (95% CI: 2.69, 10.08)

2 studies 1,016 participants reported this outcome. The studies were conducted in Africa on school-going children.

Quality of evidence: Moderate

 
  

Vitamin A fortification

Outcome/quality of evidence

Combined effect

 

Hemoglobin levels

SMD: 0.48 (95% CI: 0.07, 0.89)

2 studies with1,538 participants reported the outcome. The study by Zhang et al.[132] used four different comparison groups. The first group received low amounts of vitamin A-fortified biscuits for 9 months daily. The second group received high amount of vitamin A-fortified biscuits for 3 months daily. The third group received very high amounts of vitamin A-fortified biscuits for 3 months weekly. The standard mean differences for the three groups were 0.73 (95% CI: 0.42, 1.04), 0.62 (95% CI: 0.38, 0.85) and 0.63 (95% CI: 0.38, 0.88) respectively.

Quality of evidence: Low

Serum vitamin A concentration

SMD: 0.61 (95% CI: 0.39, 0.83)

3 studies with 2,362 participants reported the outcome. The study by Zhang et al.[132] used four different comparison groups as explained in comments for hemoglobin levels. The standard mean differences for the three groups were 0.52 (95% CI: 0.21, 0.82), 0.73 (95% CI: 0.49, 0.97) and 0.44 (95% CI: 0.22, 0.66).

Quality of evidence: Low

Vitamin A deficiency

RR: 0.39 (95% CI: 0.09, 1.74)

2 studies with 1,465 participants reported the outcome. The study by Zhang et al.[132] showed positive impacts in reducing vitamin A deficiency whereas the study by Solon et al.[110] showed negative impacts. The latter used monosodium glutamate for vitamin A fortification and the quantity of vitamin A used was much less than that used by Zhang et al.

Quality of evidence: Moderate

Calcium and vitamin D fortification

Outcome/quality of evidence

Combined effect

Calcium only

Vitamin D only

Calcium and vitamin D

Serum parathyroid hormone levels

SMD: -0.40 (95% CI: -0.56, -0.24)

SMD: -0.28 (95% CI: -0.50, -0.06)

No studies identified

SMD: -0.52 (95% CI: -0.74, -0.29)

Quality of evidence: Low

2 studies 317 participants

2 studies 327 participants

Serum vitamin D levels

SMD: 1.23 (95% CI: 0.35, 2.11)

SMD: -0.15 (95% CI: -0.41, 0.10)

SMD: 1.76 (95% CI: 0.37, 3.15)

SMD: 1.58 (95% CI: 1.28, 1.87)

Quality of evidence: Moderate

1 study 233 participants

2 studies 651 participants

1 study 235 participants

Serum calcium levels

SMD: -0.40 (95% CI: -0.59, -0.20)

SMD: -0.30 (95% CI: -0.56, -0.04)

No studies identified

SMD: -0.50 (95% CI: -0.76, -0.24)

Quality of evidence: Low

1 study 231 participants

 

1 study 235 participants

  1. Estimates in bold show significant impacts. CI, confidence intervals; RR: relative risk; SMD: standard mean difference.