Introduction

Complementary feeding starts “when breast milk alone or infant formula alone is no longer sufficient to meet the nutritional requirements of infants, and therefore, other foods and liquids are needed, along with breast milk or a breastmilk substitute” (1). The period of 6-24 months of age is one of the most critical times for growth (2) and if complementary feeding is inadequate or inappropriate, there is a much increased risk of the young child being undernourished, and of increased morbidity. About 33-45% of deaths in children less than five years of age are due to underlying undernutrition, including stunting, severe wasting, deficiencies of vitamin A and zinc, and suboptimal breastfeeding (3,4). The incidence of stunting is highest in the first two years of life, with lifelong consequences (4). Complementary feeding strategies to counter this risk include nutritional counselling to mothers, provision of complementary foods (with or without micronutrient fortification), and by simple technologies such as the lipid-based formulations (2, 3).

Methodology summary

There have been two systematic reviews (2, 5) and one Cochrane protocol (6) published since the broad-ranging review of Dewey and Adu-Afarwah in 2008. This review established the efficacy of providing complementary feeding in significantly improving growth and examined the effectiveness of complementary feeding interventions (3). The primary outcomes were growth, morbidity and child development, as well as micronutrient intake and status. The literature search focused on the period 1996 to 2006 as Caulfield et al. (7) had already demonstrated in 1999 that appropriately designed education interventions have a positive impact on feeding practices.

The search methods for all three systematic reviews followed accepted practice using electronic databases supplemented by manual follow-up. Only low- and middle-income countries (LMIC) were included. In total, Dewy and Adu-Afarwuah reviewed 42 papers from 25 countries with results from 29 efficacy trials and 13 effectiveness trials (3). Interventions were grouped as; (i) education about complementary feeding; (ii) complementary feeding or food product offering extra energy (with or without micronutrient supplementation); (iii) provision of food combined with some other strategy most commonly education for mothers; (iv) fortification with micronutrients (with no differences in energy content); and, (v) increased energy density and/or nutrient bioavailability of complementary foods through use of simple technologies (3), and so was considerably broader than the later reviews where the outcomes were growth (5) or growth and morbidity (2).

Imdad et al. (5) evaluated the effectiveness of both the provision of appropriate complementary feeding (with or without nutrition counselling), and nutrition counselling alone on improving weight and linear growth. Meta-analyses were generated for change in weight and height by pooling the results to get weighted mean differences (WMD) as studies were of different units of measurement and duration; and then a second meta-analysis was conducted to get a pooled estimate in terms of actual increase in weight (kg) and length (cm). The review included 17 studies with the primary outcomes being change in weight and height during the study period among intervention children 6-24 months of age compared to control children (5).

More recently, Lassi et al. (2) also evaluated the impact of education and provision of complementary feeding on growth, and on morbidity, in children less than two years of age. The review included randomized and non-randomized trials and programmes addressing the effect of complementary feeding (fortified or unfortified, but not micronutrients alone) and education. All studies that delivered the intervention for at least six months were included, but studies in which the intervention was given for therapeutic purposes were excluded. As recommendations were to be made for input into the Lives Saved Tool (LiST) model in this review, and the review by Imdad et al. [5], standardized Child Health Epidemiology Reference Group (CHERG) guidelines were followed (8). The review by Lassi et al. (2) included 16 studies with nine providing education on complementary feeding, six providing complementary feeding (with or without education) and one providing both as separate arms. Six of the included studies were from food-insecure populations, while ten were from food-secure.

Evidence summary

All three systematic reviews used growth as an outcome (2, 3, 5) and one systematic review included morbidity (2). In the review on efficacy and effectiveness by Dewey and Adu-Afarwuah (3), 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, educational interventions had a modest effect on weight (mean effect size = 0.28; range -0.06, 0.96) and linear growth (mean effect size 0.20, range 0.04, 0.64) (3). There were also seven efficacy trials and one effectiveness study where the only intervention strategy was the provision of complementary food, often fortified. While the results were somewhat inconsistent, two studies specifically looking for an additive effect found the inclusion of a food supplement was more effective than education alone (3). There was little information on behavioural development or micronutrient status although it was noted that it is a challenge to achieve adequate intakes of some micronutrients for 6-12 month old infants without fortified foods (3).

The results of the systematic review of Imdad et al. (5) included studies that evaluated the impact of provision of appropriate complementary foods (with or without nutritional counselling), and of nutritional counselling alone, on growth. Education of the mother about complementary feeding led to an extra weight gain of 0.30 kg (±0.26) and a gain of 0.49 cm (±0.50) in height in the intervention group compared to control. Both of the interventions were found to result in a significant increase in weight (WMD 0.34 SD, 95% CI: 0.11, 0.56 and WMD 0.30 SD, 95% CI: 0.05, 0.54 respectively) and linear growth [WMD 0.26 SD, 95% CI: 0.08, 0.43 and WMD 0.21 SD, 95% CI: 0.01, 0.41 respectively (5). Pooled results for the actual increase in weight and length showed that provision of appropriate complementary foods, with or without nutritional counselling, resulted in an extra gain of 0.25kg (±0.18) in weight and 0.54 cm (±0.38) in height in children aged 6-24 months. The overall quality of the evidence for these estimates was described as ‘moderate’ using the CHERG adaptation of the Grading, Recommendations, Assessment, Development and Evaluation (GRADE) methodology (5).

Lassi et al. (2), using combined pooled analysis of studies from both food-secure and food-insecure populations, found that education on complementary feeding alone significantly improved height-for-age (HAZ) (standardized mean difference [SMD] 0.23; 95% CI: 0.09, 0.36), weight-for-age (WAZ) (SMD 0.16; 95% CI: 0.05, 0.27), and significantly reduced the rates of stunting (relative risk [RR] 0.71; 95% CI: 0.60, 0.76) (2), although no significant impacts were observed for height and weight gain. Education on complementary feeding alone to improve compliance with feeding practice recommendations (by pooling the average uptake of various recommended foods) was found to significantly improve the uptake of these recommended foods by 62% (RR 1.62; 95% CI: 1.17, 2.26) (2).

Based on the subgroup analysis of ten studies from food-secure populations, education alone had a significant impact on height gain, HAZ scores, and weight gain, with a non-significant reduction in stunting. In the food-insecure populations, education alone significantly improved HAZ scores, WAZ scores and significantly reduced the rates of stunting, while complementary food provision, with or without education, improved HAZ and WAZ scores significantly (2). There were no studies identified for provision of complementary food in food secure populations. A combined pooled analysis of three studies indicated that provision of complementary feeding, with or without education, reduced the incidence of respiratory infections by 33% (95% CI: 0.49, 0.91) but had no significant impact on diarrhoea or fever (2).

No adverse effects were reported in any of the three systematic reviews, although one mentions the possible risks of excessive displacement of breast milk and/or unhygienic preparation and storage of complementary foods (3).

Discussion

A number of factors have been identified to influence complementary feeding practices including the socioeconomic status of caregivers, maternal education level and age, opinions of family and friends, traditional feeding practices, influence of social networks, father’s occupation, postnatal care, and lack of professional advice, all of which can influence complementary feeding practices (6,8). Nevertheless, the results of the three systematic reviews demonstrate that, even allowing for differences in the local context, interventions that provide education to mothers will significantly improve complementary feeding knowledge and practices and result in significant positive gains in linear growth and weight (2, 3, 5). The impact, including significantly reducing stunting, was generally greater when complementary feeding was added to the intervention, at least in food-insecure populations (2).

Applicability of the results

As studies in all three systematic reviews were carried out in at least 15 different LMIC including both food-secure or food-insecure populations, the widespread applicability of the findings is highly likely, not least because similar findings have been reported elsewhere and in affluent populations (10). In all studies, there was considerable variety in the complementary foods used as the intervention, the messaging, the age of the infants at the start of the studies and the duration. When a complementary food was provided, with or without concurrent strategies such as nutrition education, the studies in Africa and South Asia generally showed positive effects, while those in other regions were more variable (3), presumably due to the relatively higher prevalences of food insecurity. In such contexts, providing additional food, as well as education, may facilitate the ability to follow complementary feeding guidelines (3). In several individual studies, the impact of providing a complementary food, in combination with nutrition education, was evident only in the younger children (3) emphasizing the importance of beginning complementary feeding programmes during infancy (after the recommended six months of exclusive breastfeeding (1), when nutrient needs relative to energy intake are the highest and the ability of the child to respond to a nutritional intervention is the greatest (3, 6).

Implementation in settings with limited resources

As noted above, most studies were carried out in LMIC, which may or may not mean limited resources as many were described as food secure. In food-secure populations, rates of stunting were reduced but not significantly (2). Education in food insecure populations also improved linear growth and weight gain (significant increases in HAZ and WAZ scores) but in these settings the decrease in rates of stunting was significant (2). Two of the reviews noted the greater impact on linear growth and the use of affordable home-prepared animal-source products while noting financial constraints often limit the possibility of access (2, 3).

Further research

The relative scarcity of available studies and their heterogeneity, as well as the variety in complementary feeding interventions, made conclusions on the actual type of interventions more difficult and suggests a need for large-scale, high quality, randomized controlled trials to assess the actual impact of this intervention on growth and morbidity in children 6-24 months of age (2, 3, 5, 10).

Conclusion

Complementary feeding interventions have the potential to improve the nutritional status of children in LMIC. Provision of appropriate complementary foods, with or without nutritional education, and maternal nutritional counselling alone, lead to significant increases in weight and height in children 6-24 months of age; these interventions can also significantly reduce the risk of stunting (2). Complementary feeding interventions, by themselves, cannot change the underlying conditions of poverty that contribute to child undernutrition, and consequently complementary feeding interventions need to be implemented in conjunction with larger strategies that include improved water and sanitation, better health care and adequate housing. Nonetheless, the results of these systematic reviews indicate that programmes carefully designed to the needs of the target population, can substantially improve growth and micronutrient status and may also reduce morbidity and enhance behavioural development. The key challenge is how to implement high-quality programmes that are sustainable when delivered on a large scale (3).

References

1. Guiding principles for complementary feeding of the breastfed child. Geneva: World Health Organization; 2003. (https://www.who.int/nutrition/publications/guiding_principles_compfeeding_breastfed.pdf)

2. Lassi ZS, Das JK, Zahid G, Imdad A, Zulfiqar A, Bhutta ZA. Impact of education and provision of complementary feeding on growth and morbidity in children less than 2 years of age in developing countries: a systematic review. BMC Public Health, 2013, 13(Suppl 3):S13.

3. Dewey KG, Adu-Afarwuah S. Systematic review of the efficacy and effectiveness of complementary feeding interventions in developing countries. Maternal and Child Nutrition. 2008; 4:24–85.

4. Black RE, Victora CG, Walker SP, Bhutta ZA, Christian P, de Onis M, Ezzati M, Grantham-McGregor S, Katz J, Martorell R, Uauy R, and the Maternal and Child Nutrition Study Group. Maternal and child undernutrition and overweight in low-income and middle-income countries. Lancet. 2013;382(9890):427-451.

5. Imdad A, Yawar Yakoob M, Bhutta ZA. Impact of maternal education about complementary feeding and provision of complementary foods on child growth in developing countries. BMC Public Health. 2011; 11(Suppl 3):S25.

6. Arikpo D, Edet ES, Chibuzor MT, Odey F, Caldwell DM. Educational interventions for improving complementary feeding practices (Protocol). Cochrane Database of Systematic Reviews. 2015; Issue 6. Art. No.: CD011768.

7. Caulfield LE, Huffman SL, Piwoz EG. Interventions to improve intake of complementary foods by infants 6 to 12 months of age in developing countries: impact on growth and on the prevalence of malnutrition and potential contribution to child survival. Food and Nutrition Bulletin. 1999; 20:183–200.

8. Walker N, Fischer-Walker C, Bryce J, Bahl R, Cousens S. Standards for CHERG reviews of intervention effects on child survival. International Journal of Epidemiology. 2010; 39(suppl 1): i21-i31.

9. Ickes SB, Hurst TE, Flax VL. Maternal literacy, facility birth, and better infant and young child feeding practices and nutritional status among Ugandan children. The Journal of Nutrition. 2015; 145:2578-2586.

10. Bhutta ZA, Ahmed T, Black RE, Cousens S, Dewey K, Giugliani E, Haider BA, Kirkwood B, Morris SS, Sachdev HPS, Shekar M, Maternal and Child Undernutrition Study Group: What works? Interventions for maternal and child undernutrition and survival. The Lancet. 2008; 371(9610):417-440.

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Declarations of interests

Conflict of interest statements were collected from all named authors and no conflicts were identified.