1. Objectives

To evaluate the effectiveness of community-based supplementary feeding for promoting growth of children under five years of age in low- and middle-income countries

2. How studies were identified

The following databases were searched to January 2011:

• CENTRAL (The Cochrane Library)
• MEDLINE
• EMBASE
• CINAHL
• LILACS

In addition, WorldCat was searched for dissertations and theses, and ClinicalTrials.gov was searched for ongoing studies

3. Criteria for including studies in the review

3.1 Study type

Randomized controlled trials, including cluster-randomized trials

3.2 Study participants

Children from low- and middle-income countries, born at term (≥37 weeks’ gestation) and aged between zero and five years old

(Studies including children with malnutrition from causes other than as a result of insufficient dietary intake, such as cystic fibrosis, were excluded)

3.3 Interventions

Supplementary feeding, defined as the provision of meals, drinks, or snacks to children or families additional to their normal diets, in comparison to either normal diet or placebo (e.g., low energy drinks). Community-based interventions where the child could eat at home or at a supervised feeding centre were included

(Studies conducted in hospitals and refugee settings were excluded)

3.4 Primary outcomes

• Weight in kg, or weight-for-age Z-score (WAZ) at the end of the intervention
• Length or height in cm, or length-/height-for-age Z-score (LAZ/HAZ) at the end of the intervention
• Weight-for-length/-height Z-score (WLZ/WHZ) at the end of the intervention
• Weight or length or height gain during the intervention
• WAZ, LAZ/HAZ, and WHZ/WLZ change during the intervention
• Prevalence of underweight (WAZ<-2)
• Prevalence of stunting (LAZ/HAZ<-2)
• Prevalence of wasting (WLZ/WHZ<-2)

Secondary outcomes included mid-upper arm circumference (MUAC), skinfold thickness, head circumference, and potential adverse effects, including decrease in breastmilk intake, overweight, and diarrhoea

4. Main results

4.1 Included studies

Eight randomized controlled trials enrolling 1243 children were included:

• Two of the eight trials were cluster-randomized
• Six trials enrolled nutritionally at risk children, while the other two trials had no specific entry criteria for child nutritional status
• Four studies recruited children <2 years of age, and four were in older children
• Liquid supplements were given in two trials (both milk-based), while solid foods (micronutrient enriched porridge, food plus cornmeal and milk powder, yoghurt, bran cereal, multi-mixture, snacks) were given in six trials
• Duration of supplementation varied: three months or less (3 trials), nine to 12 months (4 trials), seven years (1 trial); as did the quantity of calories or protein provided

4.2 Study settings

• Brazil (2 trials), China, Indonesia (2 trials), Guatemala, Jamaica, and a multi-site study (Bolivia, Congo, New Caledonia, Senegal)
• Foods were delivered to the home (3 trials), or distributed centrally (5 trials)

4.3 Study settings

How the data were analysed
The effect of supplementary feeding was compared to the effect of usual diet or placebo on child growth outcomes. Separate comparisons were conducted based on nutritional status criteria for study entry: i) studies without formal assessment of malnourishment at baseline, and ii) studies with formal assessment of malnourishment at baseline. Continuous data were combined in meta-analysis to generate mean differences (MD) and 95% confidence intervals (CI). Due to substantial heterogeneity amongst the included studies, data were pooled in the following pre-specified subgroups:

• By age: younger or older than 24 months
• By nutritional status at baseline: stunted or wasted, or not stunted or wasted
• By duration of the intervention: <12 months, or ≥12 months

Results
Studies without formal assessment of malnourishment at baseline
Weight and height Z-scores at the end of the intervention
Three months of energy-protein supplementation had no effect on weight Z-scores (MD 0.19, 95% CI [-0.18 to 0.56]) or height Z-scores (MD 0.12, 95% CI [-0.31 to 0.55]) compared with no supplementation in one trial of 112 children.

Length (cm) before and after the intervention
Three years of supplementation with a high-energy protein drink compared with a low-energy protein drink resulted in a MD of 2.45 cm in change in length between children from two Guatemalan villages.

Studies with formal assessment of malnourishment at baseline
Weight (kg) at the end of the intervention
Pooled analysis of three trials among children <24 months of age demonstrated no statistically significant difference in weight between children receiving supplementary feeding and controls (MD -0.03 kg, 95% CI [-0.17 to 0.12], p=0.71; 3 trials/587 children). No difference was observed among stunted/wasted children (MD 0.21 kg, 95% CI [-0.14 to 0.55], p=0.24; 2 trials/140 children), non-stunted/non-wasted children (MD -0.08 kg, 95% CI [-0.24 to 0.08], p=0.33; 1 trial/447 children), or when supplementary feeding lasted <12 months (MD -0.05 kg, 95% CI [-0.21 to 0.59], p=0.5; 2 trials/ 512 children), or ≥12 months (MD 0.16 kg, 95% CI [-0.27 to 0.59], p=0.46; 1 trial/75 children).

Length or height (cm) at the end of the intervention
Meta-analysis of three trials in children <24 months of age found no statistically significant difference in length/height between children receiving supplementary feeding and controls (MD 0.28 cm, 95% CI [-0.11 to 0.67], p=0.15; 3 trials/587 children). In addition, no difference was observed among stunted/wasted children (MD 0.72 cm, 95% CI [-0.25 to 1.69], p=0.36; 2 trials/140 children), non-stunted/non-wasted children (MD 0.20 cm, 95% CI [-0.22 to 0.62], p=0.36; 1 trial/447 children), or when supplementary feeding lasted <12 months (MD 0.31 cm, 95% CI [-0.09 to 0.71], p=0.13; 2 trials/ 512 children), or ≥12 months (MD -0.10 cm, 95% CI [-1.61 to 1.41], p=0.15; 1 trial/75 children).

Weight (kg) and length (cm) gain
While weight gain during the intervention was not different between groups in children <24 months (MD -0.01 kg, 95% CI [-0.09 to 0.07], p=0.76; 1 trial/447 children), in those older than 24 months, treatment with supplementary food had a statistically significant effect (MD 0.22 kg, 95% CI [0.07 to 0.37], p=0.0041; 1 trial/348 children). In both trials combined, where supplementary feeding lasted <12 months, there was no difference between groups in terms of weight gain (MD 0.04 kg, 95% CI [-0.03 to 0.11], p=0.30); however, length gain was greater in those receiving supplementary food (0.19 cm, 95% CI [0.07 to 0.31], p=0.0023; 2 trials/795 children).

Weight-for-age and height-for-age Z-scores
In two Brazilian trials including 195 children, supplementary feeding of a multi-mixture to children aged between six months and six years for <12 months had no statistically significant effect on WAZ (MD -0.18 WAZ, 95% CI [-0.49 to 0.12], p=0.24) or HAZ (MD 0.02 HAZ, 95% CI [-0.29 to 0.32], p=0.92) in comparison to controls at the end of the intervention. In one Chinese study in 348 children, yoghurt supplementation in comparison to no treatment resulted in a statistically significant difference in change in WAZ (MD 0.12, 95% CI [0.05 to 0.19], p=0.00064) and change in HAZ (MD 0.05, 95% CI [0.01 to 0.08], p=0.0094).

Weight-for-length or height Z-scores
Meta-analyses based on age (<24 months versus ≥24 months), nutritional status (stunted or wasted versus not stunted or wasted), and duration (supplementary feeding <12 months) were not statistically significantly different between groups, and nor was the overall pooled estimate of change in WLZ/WHZ (MD -0.10, 95% CI [-0.33 to 0.13], p=0.42) in three trials of 260 children.

Adverse effects
In one study reporting on diarrhoea and vomiting, no differences were observed between treatment groups.

Additional outcomes
No statistically significant differences were found between treatment groups for head circumference, MUAC, and skinfold thickness.

5. Additional author observations*

In general, the methodological quality of the included trials was poor, with almost all trials being at unclear risk of selection bias, and almost all trials being at high or unclear risk of performance and detection bias due to lack of blinding. Three of the included trials were judged to be of too short a duration to have a detectable impact on linear growth, and overall, trials were of inadequate sample sizes, and anthropometric measurements were performed inconsistently.

On the basis of the evidence reviewed, the effectiveness of supplementary feeding for promoting the growth of children under five years of age living in low- and middle-income countries is limited. However, due to the underlying differences in sanitation, healthcare, and access to clean water and the strong effect these factors have on child growth, supplementary feeding trials set in one low- or middle-income country are unlikely to be generalizable to another. For children living in low- and middle-income countries, access to nutritious food, adequate health care, and sanitation is required now, and cannot wait on the results of further trials. Nevertheless, future studies are warranted, and should address the issues of research design and conduct that were inadequate in the reviewed trials.