Table of Contents Summary 25 1. Introduction 33  1.1 Importance of complementary feeding for child health 33  1.2 Guiding principles for complementary feeding 34  1.3 Scope and organization of this report 34 2. Energy and nutrients needed from complementary foods 35  2.1 Energy, protein and lipids 35  2.2 Micronutrients 35 3. Methods 36  3.1 Sources searched and search strategy 36  3.2 Measurement of the treatment effect of interventions 36  3.3 Evaluation of methodological quality and level of evidence 37  3.4 Number of relevant studies identified 38 4. Findings of the systematic review 38  4.1 Types of intervention strategies 38   4.1.1 Educational interventions 38   4.1.2 Provision of food offering extra energy (with or without micronutrient fortification) 43   4.1.3 Micronutrient fortification of complementary foods 43   4.1.4 Increasing energy density of complementary foods through simple technology 46   4.1.5 Categorization of results by intervention strategy 46  4.2 Growth outcomes 46   4.2.1 Interventions using educational approaches 46   4.2.2 Interventions in which provision of complementary food was the only treatment 49   4.2.3 Interventions in which provision of complementary food was combined with another strategy, usually education for mothers 51   4.2.4 Interventions in which complementary foods were fortified with additional micronutrients 53   4.2.5 Interventions to increase energy density of complementary foods 55  4.3 Morbidity outcomes 55   4.3.1 Interventions using educational approaches 55   4.3.2 Interventions in which provision of complementary food was the only treatment 57   4.3.3 Interventions in which provision of complementary food was combined with another strategy, usually education for mothers 57   4.3.4 Interventions in which complementary foods were fortified with additional micronutrients 58   4.3.5 Interventions to increase energy density of complementary foods 59  4.4 Child development 61   4.4.1 Interventions in which provision of complementary food was the only treatment 61   4.4.2 Interventions in which complementary foods were fortified with additional micronutrients 62  4.5 Micronutrient intake 63   4.5.1 Intervention studies using educational approaches 63   4.5.2 Interventions in which provision of complementary food was the only treatment 64   4.5.3 Interventions in which provision of complementary food was combined with another strategy, usually education for mothers 64   4.5.4 Interventions in which complementary foods were fortified with additional micronutrients 65   4.5.5 Interventions to increase energy density of complementary foods 66  4.6 Iron status 66   4.6.1 Intervention studies using educational approaches 66   4.6.2 Interventions in which complementary food was provided, with or without another strategy such as education for mothers 68   4.6.3 Interventions in which commercially processed complementary foods were fortified with iron or multiple micronutrients 68   4.6.4 Interventions in which home fortification of complementary foods was the primary intervention 68  4.7 Zinc status 72   4.7.1 Interventions in which complementary foods were fortified with additional micronutrients, either commercially or with home fortification 72  4.8 Vitamin A status 72   4.8.1 Interventions in which complementary foods were fortified with additional micronutrients, either commercially or with home fortification 72 5. Discussion 75  5.1 Impact of complementary feeding interventions on growth 75  5.2 Impact of complementary feeding interventions on morbidity 77  5.3 Impact of complementary feeding interventions on child development 78  5.4 Impact of complementary feeding interventions on micronutrient intake 78  5.5 Impact of complementary feeding interventions on micronutrient status 78  5.6 Conclusions 79 Acknowledgments 82 References 82 Summary Introduction Complementary feeding interventions are usually targeted at the age range of 6–24 months, which is the time of peak incidence of growth faltering, micronutrient deficiencies and infectious illnesses in developing countries. After 2 years of age, it is much more difficult to reverse the effects of malnutrition on stunting, and some of the functional deficits may be permanent. Therefore, interventions that are effective at reducing malnutrition during this vulnerable period should be a high priority. Although several types of interventions can be targeted to this age range (e.g. micronutrient supplementation), a food‐based, comprehensive approach may be more effective and sustainable than programmes targeting individual nutrient deficiencies. For this review, a broad definition of ‘complementary feeding interventions’ is used so as to capture the full range of strategies that can be used. Scope and methods of the review The interventions described in this review generally include one or more components related to the Guiding Principles for Complementary Feeding of the Breastfed Child (PAHO/WHO 2003). The 10 guiding principles cover: (1) duration of exclusive breastfeeding and age of introduction of complementary foods; (2) maintenance of breastfeeding; (3) responsive feeding; (4) safe preparation and storage of complementary foods; (5) amount of complementary food needed; (6) food consistency; (7) meal frequency and energy density; (8) nutrient content of complementary foods; (9) use of vitamin‐mineral supplements or fortified products for infant and mother; and (10) feeding during and after illness. This review includes any relevant intervention that targeted children within the age range of 6–24 months. In some cases, the intervention may have included children older than 24 months, but in all studies at least some of the children were between 6 and 24 months. The assumption is that many of the children in these studies were breastfed, although a certain proportion will have terminated breastfeeding before 24 months. Although strategies for optimizing the duration of exclusive breastfeeding or increasing the total duration of breastfeeding may have a direct influence on several of the outcomes of interest, this review will not cover those strategies because another report will review those results. The primary outcomes of interest for this review include growth, morbidity and child development. Micronutrient intake and micronutrient status were also included as outcomes because of their link to these key functional outcomes. Studies that assessed the impact of complementary feeding interventions on feeding practices only were not included because of time constraints and because it has been demonstrated previously that appropriately designed interventions can have a positive impact on feeding practices (Caulfield et al. 1999). For most intervention strategies and outcomes, the literature search was focused on the period from 1996 to 2006, as the previous review by Caulfield et al. (1999) covered the period from 1970 to 1997. For certain interventions not covered in the previous review (i.e. using amylase to increase energy density and interventions focused on iron status outcomes), studies dating back to 1990 were included. Only studies conducted in developing countries were included. The search was conducted using electronic methods, inspection of websites of key private voluntary organizations and the bibliographies of published papers, and personal contacts. The two authors of this review independently assessed the quality of each of the reviewed studies, and those scored as 2– (non‐randomized studies with a high risk of bias) were not included in the tabulation of results. In total, 42 papers were included in the review. These papers report results from 29 efficacy trials and 13 effectiveness studies or programme reports from 25 developing countries. Interventions were considered efficacy trials if there was a high degree of assurance of delivery of the ‘treatment’, generally under carefully controlled research conditions (e.g. provision of a fortified complementary food with frequent follow‐up to assess adherence). Evaluations of interventions carried out in a programme setting, generally with less ability to control delivery of and adherence to ‘treatment’, were considered effectiveness studies. To compare growth (weight and length) results across studies (when these results were reported as means ± SD), we calculated the treatment effect size for each outcome of interest using the formula: When possible, the effect sizes for each outcome were averaged across interventions to obtain a rough estimate of overall impact. Effect size can be categorized as small (∼0.2), medium (∼0.5) or large (∼0.8). Interventions were grouped into five categories depending on the main strategy used: 1 education about complementary feeding as the main treatment, 2 complementary food or a food product offering extra energy (with or without added micronutrients) provided as the only treatment, 3 provision of food combined with some other strategy, usually education for mothers, 4 fortification of complementary foods (centrally processed fortified foods or home‐fortification products) with micronutrients (with no difference in energy provided to intervention vs. control groups), and 5 increased energy density and/or nutrient bioavailability of complementary foods through the use of simple technologies. Some studies had more than one intervention group and may thus be included in more than one of the categories. In these situations, only the results for the intervention groups that are relevant to the comparison in question are included in that section. Some of the interventions targeted only malnourished children, but most were aimed at all children in the target age range. Results Growth Nearly all of the studies assessed growth as an outcome. There were six efficacy trials and five effectiveness studies in which the main intervention strategy was education about complementary feeding. Taking these 11 studies together, educationa