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Introduction

COMPLEMENTARY FEEDING OF INFANTS AND CHILDREN

Complementary feeding is the introduction of foods to an infant’s diet in addition to human milk or formula. The period when complementary food is introduced marks the transition of the infant from a liquid milk diet to one that incorporates new foods with variations in textures and flavors and occurs consonant with the development of gross, fine motor, and verbal and nonverbal communication skills. The World Health Organization (WHO) recommends that complementary feeding begins at about 6 months of age, and not before 4 months of age, with continued breastfeeding until 2 years of age or older (Pérez-Escamilla et al., 2017; WHO, n.d., 2003). The American Academy of Pediatrics also recommends the introduction of complementary foods at about 6 months, and not before 4 months, with continued breastfeeding for as long as mutually desired by the mother and child for 2 years or beyond (Meek and Noble, 2022). For infants who are not breastfed at 6 months of age, it is recommended that they be fed commercially prepared infant formulas in conjunction with complementary foods until 1 year of age (NASEM, 2020). During the period from 6 months to 2 years of age, the infant diet often follows a progression from specially prepared pureed and mashed foods, to easily chewed foods, to solids (e.g., chopped/diced), and finally to the family diet, meaning the types of foods and beverages that caregivers and other household members eat (Black et al., 2017; Dewey et al., 2021).

The social and ecological systems in which complementary feeding takes place shapes the child’s dietary intake and eating behaviors. The

family and caregivers’ feeding decisions and practices are influenced by their knowledge, perceptions, cultural values, and intergenerational experience with parenting, eating, nutrition, and child development, as well as by family finances and stressors and access to nutritious foods (Berge et al., 2018; Rhodes et al., 2016). Knowledge and perceptions are developed through broader cultural and other environmental contexts such as input from health care providers (Kleinman and Greer, 2020); programs such as the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) (USDA, 2019); other information sources such as books, social media and food and beverage marketing; the family’s social network (Majee et al., 2017; UNICEF, 2020); and mediators such as food and water availability, maternal stress, and limited physical activity opportunities, among others (Ingalls et al., 2019). These relationships have been characterized by different research groups and applied in multiple contexts (Pérez-Escamilla et al., 2017). The nutrition ecology, which is the social and environmental factors that impact choices of both what to feed and how to feed, includes factors extending from the home through communities, systems, and local and national policies (Raiten and Bremer, 2023).

For infants and young children under age 2 years healthy complementary feeding behaviors are essential for age-appropriate growth and social, emotional, and cognitive development (Birch and Doub, 2014; Fisher and Dwyer, 2016). Indeed, adequate complementary feeding is a key component of the evidence-based Global Nurturing Care Framework for Early Childhood Development (Britto et al., 2017; WHO et al., 2018) and as such is part of the foundation for supporting healthy growth and development of children since gestation (Pérez-Escamilla et al., 2017). Parents and caregivers need appropriate guidance on both (1) infant and young child energy, nutrient, and dietary pattern requirements; and (2) the behavioral aspects of feeding and eating. The recent National Academies of Sciences, Engineering, and Medicine (the National Academies) consensus study report titled Feeding Infants and Children from Birth to 24 Months (NASEM, 2020) summarized existing recommendations on what and how to feed infants and young children and noted that the preponderance of guideline documents reviewed provide guidance on what to feed, with about one-third of these guidelines also providing recommendations on how to feed. Furthermore, the Dietary Guidelines for Americans, 2020‒2025 addressed, for the first time, feeding recommendations for infants and young children (USDA and HHS, 2020); these guidelines also had a stronger focus on what to feed than on how to feed, while endorsing responsive feeding approaches.

Existing Evidence on What to Feed Infants and Children Ages 6‒24 Months

At around 6 months of age, the nutritional needs of the infant may no longer be met by human milk or formula alone, which is why introducing complementary foods at this time is recommended (NASEM, 2020; Pérez-Escamilla et al., 2017; WHO, n.d., 2001). Based on the results of systematic reviews conducted by the U.S. Department of Agriculture’s Nutrition Evidence Systematic Review (Stoody et al., 2019), the Dietary Guidelines for Americans, 2020‒2025 recommends introducing nutrient-dense, developmentally appropriate foods at around 6 months of age (USDA and HHS, 2020). These guidelines, and others, recommend introducing iron, zinc, and vitamin D‒rich foods and avoiding added sugars and high-sodium foods (NASEM, 2020; USDA and HHS, 2020). In addition, it is recommended that a healthy beverage pattern be established, in which small amounts of water can be given after 6 months of age; cow’s milk, plant-based milk alternatives, and juice should not be introduced before 12 months of age; and sugar-sweetened beverages such as toddler milks, and beverages with caffeine should be avoided in children under 24 months of age (NASEM, 2020; USDA and HHS, 2020).

Existing Evidence on How to Feed Infants and Children Ages 6‒24 Months

The existing research on complementary feeding practices recognizes that complementary feeding ideally occurs through ongoing and reciprocal interactions between the caregiver and the developing child (Birch and Doub, 2014; Black and Hurley, 2007; Jansen et al., 2018; Pérez-Escamilla et al., 2017, 2021). In this evolving relationship, the caregiver determines the pattern and progression of the foods and beverages that are offered and how they are offered, with considerations for factors such as the child’s appetite and developing tastes and preferences. The child responds to the foods or feeding style through facial expressions, gestures, motor movements, or vocalizations (CDC, 2021). Caregivers may adjust what is fed and/or the manner of feeding in response to the child’s reactions, and over time, eating behaviors are established in the young child (Wood et al., 2020).

Responsive feeding is part of a broader domain of responsive parenting, in which feeding, soothing, sleep, and physical activity are all influenced through the dyadic interactions between caregivers and infants (Black and Aboud, 2011; Landry et al., 2006; Pérez-Escamilla et al., 2021). Responsive feeding is an approach to feeding that is sensitive to the

child’s hunger and fullness cues, as well as the child’s emotional and developmental needs (Birch, 2016; Pérez-Escamilla et al., 2017) (see Figure 1-1). Key principles of responsive feeding include recognizing hunger and fullness cues, offering a variety of foods, encouraging self-feeding, and creating a positive feeding environment (Black and Aboud, 2011). As described by Pérez-Escamilla et al. (2017, p. 17):

BACKGROUND FOR THE STUDY

Adequate nutrition during an infant’s first 1,000 days, beginning in pregnancy and extending to 2 years of age, supports optimal growth and development of children (Marshall et al., 2022; Pérez-Escamilla et al., 2023; Schwarzenberg and Georgieff, 2018). Government officials recently highlighted gaps and opportunities to strengthen federal research, surveillance, programs, and communication and dissemination efforts to improve nutrition during this time period (Hamner et al., 2022). There are federal government programs and programmatic initiatives aimed

at supporting nutrition during the first 1,000 days, such as WIC¹ and the Child and Adult Care Food Program (CACFP)² for families with low income. Opportunities exist to expand efforts by identifying new and/or supplementary interventions or expanding the reach of existing programs to broader target populations to improve nutrition.

Research studies have examined interventions aimed at improving nutrition for infants and young children, but many of these interventions were conducted in controlled settings and their effectiveness and scalability to practical, real-life settings remains unknown. Gaps in understanding include:

1. What interventions can potentially affect infant nutrition and feeding behaviors and/or outcomes outside of controlled clinical and research settings;
2. What interventions can be implemented at a community or state level; and
3. If and how interventions could complement existing federal-level programs and reach underserved populations.³

THE COMMITTEE’S TASK AND APPROACH

The Centers for Disease Control and Prevention requested that the National Academies conduct a scoping review to identify promising complementary feeding interventions (see Box 1-1). Specifically, the committee was asked to identify information on interventions aimed at improving infant feeding behaviors in health care systems, early care and education settings, and university cooperative extension programs. Biographical sketches of the committee members are included in Appendix A.

As directed by the Statement of Task (see Box 1-1), the committee gathered evidence from several sources, including published peer-reviewed and gray literature and an open session with the sponsor (see Appendix

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¹ See https://www.fns.usda.gov/wic (accessed August 21, 2023).

² See https://www.fns.usda.gov/cacfp (accessed August 21, 2023).

³ At the request of the sponsor, the committee was asked to note the ability of the intervention to reach higher risk populations. Throughout the report, the committee will use the term “underserved populations” to refer to populations that have been systematically denied a full opportunity to participate in aspects of economic, social, and civil life (White House, 2021). Specifically, in the U.S. context, this may include families that: are Asian, Black, Hispanic/Latino, Indigenous, and/or Native Hawaiian or Pacific Islander; have low incomes; are located in rural or urban areas with limited access to healthy foods; speak languages other than English in the home; or experience other systematic discrimination or disadvantage. When possible, specific language about the characteristics of study populations has been used in sections of the report describing study findings; additional details about characteristics of study populations are available in Appendix E.

B). The committee identified and collected information on interventions related to complementary feeding. Details on the committee’s methodological approach are included in Chapter 2.

Scope of the Report

The aim of this report is to scope the evidence on interventions aimed at improving feeding behaviors of infants and young children (see Box 1-1). The committee interpreted the task by acknowledging the difference between a scoping review and a systematic review. While scoping reviews typically follow a systematic approach, they are intended to map and summarize evidence on a topic and identify themes, concepts, and knowledge gaps (Tricco et al., 2018). Systematic reviews are useful for answering clearly defined questions by synthesizing the results or outcomes of included articles via meta-analysis or qualitative analysis (Aromataris and Munn, 2020). Scoping reviews are often used to determine if there is sufficient high-quality evidence available to undertake a systematic review (Munn et al., 2018).

The scoping review that was conducted in developing this report is limited to complementary feeding interventions. Based on the Statement

of Task (see Box 1-1) and conversations with the sponsor during the open session, the committee determined that interventions solely focused on breastfeeding or the timing of the introduction of complementary foods were out of scope. At the direction of the study sponsor, the committee also included interventions that complemented existing federal programs targeting at-risk children under 2 years of age and their caregivers that may influence infant and young child feeding behaviors and practices (e.g., WIC and home visiting programs).

ORGANIZATION OF THE REPORT

This report is organized into six chapters. The current chapter describes the background for the study and the Statement of Task. Chapter 2 describes the committee’s methodological approach to its task and Chapter 3 provides the context and considerations that were taken into account while reviewing the literature and developing the report. Chapter 4 presents the findings from the scoping review and the committee’s assessment of relevant evidence. Chapter 5 further discusses the committee’s assessment of the evidence, specifically interventions identified that were particularly informative. Then, Chapter 6 discusses the potential for scalability, and, finally, Chapter 7 presents the committee’s identified considerations and implications for designing future infant feeding interventions.

REFERENCES