Introducing Complementary Feeding – When and How to Start?

Introduction

Breastfeeding is the best and most accessible method of disease prevention for both children and adults. During the first six months of life, it fully satisfies the infant’s nutritional needs. After the sixth month, breast milk alone no longer provides all the necessary nutrients for optimal growth and development, making it essential to know how to introduce complementary foods properly. Appropriate introduction of complementary feeding allows the digestive system to gradually adapt, introduces new tastes and textures, and ensures vital nutrients needed for continued healthy development.

Both the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) and the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition (NASPGHAN) recognize the benefits of breastfeeding for both mothers and babies, and promote it as the healthiest feeding option. ESPGHAN’s Nutrition Committee places breastfeeding at the center of its research, focusing on its impact on both childhood and long-term health.

This brings us to the key question: when should complementary feeding begin?

What Is Complementary Feeding?

According to the World Health Organization (WHO), complementary feeding refers to all solid or liquid foods introduced in addition to breast milk.

ESPGHAN defines complementary feeding as the introduction of all solid and liquid foods other than breast milk and infant formula—a more practical and clearer definition for healthcare providers and parents alike.

Some authors use the term “weaning foods,” referring to food that gradually replaces breastfeeding. However, this definition is considered inappropriate, as it is crucial for both mothers and babies to continue breastfeeding even after complementary feeding has been introduced.

The complementary feeding period is defined as the time during which other foods or liquids are given alongside breast milk.

Due to the increasing prevalence of malnutrition in developing countries and obesity and disordered eating in developed countries, both WHO and UNICEF have made complementary feeding a top priority in early childhood nutrition strategies.

The Importance of Timely Introduction

Introducing complementary foods at the right time is important for nutritional and developmental reasons, and it helps facilitate the transition from exclusive breastfeeding to a family diet. As the infant grows, breast milk alone no longer provides sufficient energy, macronutrients, and micronutrients—necessitating their supplementation through solid foods.

Introducing complementary foods too late or too early can have serious consequences:

• Late introduction may lead to malnutrition, which affects motor and cognitive development and may result in later academic challenges. It also increases the risk of infections, some of which may be life-threatening.
• Poorly balanced or inadequate complementary feeding—either in quality or quantity—can result in nutritional deficiencies. Its quality depends largely on parental knowledge, economic conditions, and the environment the child lives in.

Breastfeeding and Complementary Feeding

Recommendations vary between countries regarding the timing and content of complementary feeding due to a lack of strong scientific evidence about the short- and long-term health effects of its introduction.

In 2001, during its 54th assembly, WHO recommended exclusive breastfeeding until six months of age, followed by continued breastfeeding with complementary foods until two years or longer.

In 2017, ESPGHAN updated its guidance, also promoting exclusive breastfeeding for the first six months as an ideal goal. However, they emphasized that complementary feeding should not begin before four months of age and should not be delayed beyond six months. The optimal timing should be individualized based on the child’s development and readiness.

UNICEF therefore suggests the following:

• a global strategy for improving infant and childhood complementary feeding;
• the first step: improving the nutritional quality of complementary food, considering the possible differences between rural and urban areas; locally available food should be the priority for all children;
• the second step: providing assistance with regard to food, micronutrients and lipids to all endangered children (children who are not breastfed, children from very poor families, HIV-infected children, malnourished children or children living in extreme conditions);
• the third step: directed towards educating mothers, as well as towards the health and social environment in general
• the fourth important step: securing support for developing countries so that they may enforce the International Code of Marketing of Breast-Milk Substitutes at their respective national levels, and that complementary foods and infant nutrition in general may follow international expert recommendations. The continuing education of healthcare workers is an essential part of this.

Signs of Readiness & Developmental Aspects

Recent guidelines emphasize that the decision to begin complementary feeding should be based on signs of developmental readiness, not only on age. Some key indicators include:

• The baby can sit upright with support
• Good head and neck control
• Showing interest in food when others are eating
• Ability to move food to the back of the mouth and swallow
• Diminishing tongue-thrust reflex that pushes food out

From a neuromotor development perspective:

• 4–6 months: Reduction in tongue-thrust reflex and early swallowing skills begin to appear.
• 6 months: Babies can sit with support, maintain head control, and use their lips to take food from a spoon.
• 7–8 months: Development of side-to-side tongue movement begins, enabling chewing motions.
• 8–10 months: Pincer grasp emerges, allowing self-feeding of small food pieces.
• 9–12 months: Ability to hold a cup with both hands and attempts to use a spoon independently.

Research shows that missing the “critical window” between 6–10 months for introducing more textured foods may lead to future feeding difficulties.

Nutrition & Key Nutrients in Complementary Feeding

As breast milk becomes insufficient to meet the growing infant’s nutritional demands, complementary foods must provide adequate energy and essential micronutrients.

Growth Patterns and Nutritional Standards

The WHO growth charts are now the gold standard for assessing children up to five years old, regardless of ethnicity or socioeconomic status. These curves are based on the growth of infants who were exclusively or predominantly breastfed for at least four months and continued breastfeeding for at least 12 months.

Research has shown that breastfed babies tend to have a different growth trajectory compared to formula-fed infants, typically gaining weight more slowly after the first few months—a pattern now considered healthy. In contrast, rapid early weight gain seen in formula-fed infants has been associated with an increased risk of obesity.

Iron and Zinc

Iron is a critical micronutrient after 6 months of age. Babies are born with iron stores sufficient for the first 4–6 months, but beyond that, dietary intake must meet their needs. For exclusively breastfed infants born at term with normal birth weight, iron supplementation may not be necessary in the first 6 months. However, complementary feeding must include iron-rich foods such as:

• Red meat (beef, lamb)
• Iron-fortified cereals
• Legumes (beans, lentils)
• Leafy green vegetables

Zinc is another essential nutrient important for growth and immune function. While absorption from breast milk is efficient, zinc requirements increase after 6 months, and good sources include:

• Meat
• Shellfish
• Legumes

Nutrition & Key Nutrients in Complementary Feeding

As breast milk becomes insufficient to meet the growing infant’s nutritional demands, complementary foods must provide adequate energy and essential micronutrients.

Growth Patterns and Nutritional Standards

The WHO growth charts are now the gold standard for assessing children up to five years old, regardless of ethnicity or socioeconomic status. These curves are based on the growth of infants who were exclusively or predominantly breastfed for at least four months and continued breastfeeding for at least 12 months.

Research has shown that breastfed babies tend to have a different growth trajectory compared to formula-fed infants, typically gaining weight more slowly after the first few months—a pattern now considered healthy. In contrast, rapid early weight gain seen in formula-fed infants has been associated with an increased risk of obesity.

Iron and Zinc

Iron is a critical micronutrient after 6 months of age. Babies are born with iron stores sufficient for the first 4–6 months, but beyond that, dietary intake must meet their needs. For exclusively breastfed infants born at term with normal birth weight, iron supplementation may not be necessary in the first 6 months. However, complementary feeding must include iron-rich foods such as:

• Red meat (beef, lamb)
• Iron-fortified cereals
• Legumes (beans, lentils)
• Leafy green vegetables

Zinc is another essential nutrient important for growth and immune function. While absorption from breast milk is efficient, zinc requirements increase after 6 months, and good sources include:

• Meat
• Shellfish
• Legumes

Allergenic Foods, Long-Term Health, and Feeding Guidelines

Recent studies have reshaped our understanding of allergy prevention. Landmark research, such as the LEAP, EAT, and PETIT studies, show that introducing allergenic foods between 4 and 6 months can significantly reduce the risk of allergies:

• Peanut allergies reduced by 70–80%
• Egg allergies reduced by 40–50%
• Benefits extend to other common allergens

Key takeaways from current international guidelines include:

• Do not delay introducing allergenic foods beyond 6 months
• Introduce allergens gradually and in small amounts
• Continue regular exposure (2–3 times per week) once introduced
• Take a personalized approach for children at high risk (e.g., with eczema or family history of allergies)

Additionally, research shows that maternal dietary restrictions during pregnancy and breastfeeding do not prevent allergies in the child and are not recommended.

Milk Intake, Growth, and Cognitive Development

Current recommendations emphasize the continued importance of breastfeeding during complementary feeding for several reasons:

• Provides nutritional security
• Protects against infections
• Supports emotional bonding
• Enhances immune system development

If breastfeeding is no longer possible, infant formula should be used instead of cow’s milk, which is not recommended before 12 months due to:

• Low iron content and poor bioavailability
• Risk of gastrointestinal bleeding
• Inadequate protein and nutrient composition
• Increased renal solute load

Furthermore, research links early cow’s milk intake to potential metabolic issues, rapid growth, and higher risk for overweight and hypertension.

Skimmed milk should also be avoided before age 2, as it lacks essential fats needed for brain development.

Long-Term Health Outcomes and Final Recommendations

Studies confirm that early nutritional interventions can have lifelong health benefits. Between 6 and 24 months of age, appropriate complementary feeding influences:

• Neurological development
• Immune regulation
• Gut microbiome composition
• Metabolic programming

Key nutrients with known effects on cognitive development include:

• Iron – for brain oxygenation and development
• Zinc – for DNA synthesis and cell growth
• Iodine – for thyroid hormone production and brain development
• Choline – for hippocampal function and memory
• Vitamin B12 – for myelination and neural function
• DHA and ARA – essential fatty acids for cognitive and visual development

Delaying introduction of textures beyond 10 months may lead to feeding problems, while introducing sugar and salt too early can promote unhealthy taste preferences and increase risk for obesity and hypertension.

The timing and quality of complementary foods also affect long-term risk for:

• Cardiovascular disease
• Allergies
• Celiac disease (e.g., introducing gluten between 4–6 months, preferably while breastfeeding)
• Dental caries (avoid sugary drinks and practice early oral hygiene)

Summary: Key Recommendations for Parents

• Exclusively breastfeed for the first 6 months, if possible
• Begin complementary feeding between 4 and 6 months, depending on readiness
• Continue breastfeeding up to 2 years or beyond
• Introduce iron- and zinc-rich foods early
• Include allergenic foods between 4–6 months for allergy prevention
• Avoid cow’s milk as a main drink before 12 months
• Delay added sugar and salt
• Offer a variety of textures by 10 months
• Focus on responsive feeding and positive mealtime experiences

Proper complementary feeding lays the foundation for lifelong health and well-being. Parents and caregivers should feel empowered by evidence-based guidelines and seek personalized support from pediatric professionals when needed.

Use tools like the LittleDot app to track feeding, symptoms, and milestones, and to consult pediatricians or nutritionists directly via chat or video. A well-informed parent is a confident and empowered caregiver.

References:

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12. http://www.who.int/nutrition/topics/complementary_feeding/en/index.html