1.1. Background

Complementary feeding – defined as the process of providing foods when breast milk or milk formula alone are no longer adequate to meet nutritional requirements – generally starts at age 6 months and continues until age 23 months, although breastfeeding may continue beyond this period (4). This is a developmental period when it is critical for children to learn to accept healthy foods and beverages and establish long-term dietary patterns (5). It also coincides with the peak period for risk of growth faltering and nutrient deficiencies.

The immediate consequences of malnutrition during these formative years, as well as in utero and the first 6 months of life, include impaired growth, significant morbidity and mortality, and delayed motor, cognitive, and socioemotional development. It can later lead to increased risk of noncommunicable diseases (NCDs). In the long term, early childhood undernutrition leads to reduced work capacity and earnings and, among girls, reduced reproductive capacity (6). Inappropriate complementary feeding can result in overweight, type 2 diabetes, and disability in adulthood (6). The first 2 years of life are also a critical period for brain development, the acquisition of language and sensory pathways for vision and hearing, and the development of higher cognitive functions (8).

The most recent UNICEF-WHO-World Bank Group Joint Child Malnutrition Estimates indicate that stunting affects 22.3% (148 million), wasting affects 6.8% (45 million), and overweight affects 5.6% (37 million) of children under 5 years of age globally (14). Risk of stunting and wasting is concentrated during the first 5 years of life and children in this age group are also at risk of obesity.

In 2012, the World Health Assembly in its Resolution WHA65.6 endorsed a Comprehensive implementation plan for maternal, infant and young child nutrition, which specified six global nutrition targets for 2025 (15). Appropriate complementary feeding, essential to fostering healthy growth, is directly related to three of these six targets: 1) 40% reduction in the number of under-5s who are stunted; 2) reduce and maintain childhood wasting to less than 5%; and 3) no increase in childhood overweight. Appropriate complementary feeding is also fundamental to achieving several of the targets in the second Sustainable Development Goal (16).

1.2. Purpose and target audience

This guideline provides global, normative evidence-based recommendations on complementary feeding of infants and young children 6–23 months of age. The recommendations are intended for a wide audience, including policymakers, and technical and programme staff at government institutions and organizations involved in the design, implementation and scaling of programmes for infant and young child feeding. The guideline may also be used by caregivers, health-care professionals, clinicians, academic and research institutions, and training institutions.

1.3. Objective

The objective of this guideline is to help Member States, United Nation’s agencies, nongovernmental organizations and other stakeholders to make informed recommendations about complementary feeding in their efforts to achieve the Global Strategy for Infant and Young Child Feeding (17), the SDGs (16), the global targets set in the Comprehensive implementation plan on maternal, infant and young child nutrition (15), and the Global Strategy for Women’s, Children’s, and Adolescents’ Health (2016–2030) (18).

1.4. Population of interest

The guideline covers infants and young children who were full term at birth and who live in low-income countries, middle-income countries and high-income countries. It considers the needs of both breastfed and non-breastfed children and, unless noted, applies globally to all infants and young children 6–23 months of age. It provides public health recommendations, recognizing that children all infants and young children should be managed individually so that undernutrition, micronutrient deficiencies, overweight or obesity, or other adverse outcomes are identified, and appropriate action taken. This guideline does not address the needs of pre-term and low-birthweight infants, children with or recovering from acute malnutrition and serious illness, children who are disabled, or children living in emergencies. Except for children with disabilities, the needs of these children are addressed in other WHO guidelines.

1.5. Scope

The guideline is intended to be food-based. Although it considers nutrient needs of infants and young children, it does not specify levels of nutrients to be consumed or avoided (such as micronutrient levels or energy). It also does not specify quantities of foods to be consumed as these would vary by age, activity level, metabolism and local contexts and so cannot be defined at a global level. However, in making recommendations on what foods need to be consumed, the GDG did consider it important to ensure that nutrient needs can be met. The guideline does not address issues of food safety.

1.6. Justification

This guideline updates the Pan American Health Organization/WHO guideline Guiding principles for complementary feeding of the breastfed child (2003) and the WHO guideline Guiding principles for feeding non-breastfed children 6–24 months of age (2005) (1, 2). Both guidelines focused on undernutrition and, therefore, while relevant to low- and middle-income countries (LMICs) they were less relevant to high-income countries. The guidelines were developed prior to the publication of the WHO handbook for guideline development and were therefore not subject to the same rigorous procedures as current guidelines. Additionally, over the past 20 years there have been numerous new publications related to complementary feeding. Overweight and obesity have increased in children globally. Many children are only partially breastfed and thus were not clearly assigned to one or the other document. For these reasons, the WHO Department of Nutrition and Food Safety decided it was timely to update the earlier guidance to address both breastfed and non-breastfed children and those living in low-, middle- and high-income countries in a single guideline.

1.7. Related WHO Guidelines

The following WHO guidelines are relevant to this guideline:

• Guiding principles for complementary feeding of the breastfed child (1)
• Guiding principles for feeding non-breastfed children 6–24 months of age (2)
• WHO recommendations for postnatal care for the mother and newborn (19)
• Guideline: sugars intake for adults and children (20)
• Guideline: daily iron supplementation in infants and children (21)
• Guideline: assessing and managing children at primary health-care facilities to prevent overweight and obesity in the context of the double burden of malnutrition (22)
• Guideline: integrated management of children in all their diversity with obesity (forthcoming) (23)
• Guideline: vitamin A supplementation in infants and children 6–59 months of age (24)
• Improving early childhood development: WHO guideline (25)
• WHO recommendations on antenatal care for a positive pregnancy experience (26)
• Guideline: carbohydrate intake for adults and children (5)
• Guideline: saturated fatty acid and trans-fatty acid intake for adults and children (27)
• Guideline: total fat intake for the prevention of unhealthy weight gain in adults and children (28)
• Guideline: use of non-sugar sweeteners (29)

Other relevant WHO documents include:

• The optimal duration of exclusive breastfeeding: report of an expert consultation (30)
• Healthy diet fact sheet (31)
• Guideline: sodium intake for adults and children (32) (for persons 2 years of age and older)
• Guideline: potassium intake for adults and children (33) (for persons 2 years of age and older)
• Guidance on ending the inappropriate promotion of foods for infants and young children (34)
• WHO global report on sodium intake reduction (35)
• WHO Manual on sugar-sweetened beverage taxation policies to promote healthy diets (36)
• WHO: five keys to safer food manual (37)
• Nurturing care for early childhood development: a framework for helping children survive and thrive to transform health and human potential (38)
• Guideline: delayed umbilical cord clamping for improved maternal and infant health and nutrition outcomes (39)
• WHO recommendations for care of the preterm or low birth weight infant (40)
• Nutrient and promotion profile model: supporting appropriate promotion of food products for infants and young children 6–36 months in the WHO European Region (41)