Complementary Feeding in Infants: Nutritional, Neurobiological, and Relational Aspects

Complementary feeding represents an essential stage in infant development, during which breast milk or formula is accompanied by solid and semi-solid foods to meet the evolving nutritional requirements. This transition is supported by progressive gastrointestinal, neurological, and behavioral maturation, and it promotes the acquisition of fundamental feeding and relational skills that are crucial for long-term health.

This article examines the most recent evidence in the medical and nutritional fields, with particular focus on the timing of introduction, the composition of foods, and the effects on neuropsychological and immune development.

Complementary feeding (CF) is defined as the process of introducing foods other than breast milk or formula, with the aim of covering the infant’s energy and micronutrient needs starting around the sixth month of life, in accordance with recommendations from the World Health Organization (WHO, 2003) and leading scientific societies (ESPGHAN, 2017; SIP, 2019).

This phase reflects the natural evolution of infant nutrition, in synergy with the maturational changes of the digestive, neurological, and immune systems.
Beyond its nutritional role, complementary feeding promotes the establishment of positive eating habits and strengthens the relationship between the caregiver and the child through shared experiences around food.

 

Gastrointestinal Maturation and the Onset of Complementary Feeding

Around 5–6 months of age, the infant reaches a stage of digestive maturity that allows for optimal management of solid foods:

• Increased production of digestive enzymes (salivary amylase, lipase, pancreatic proteases);
• Improved intestinal motility and absorptive capacity;
• Development of oral immune tolerance, mediated by regulatory T cells of the GALT (Gut-Associated Lymphoid Tissue).

The recommended period for initiating CF lies between the 17th and 26th week of life, taking into account the infant’s neurobehavioral readiness, as demonstrated by:

• Control of head and trunk in a seated position;
• Disappearance of the tongue-thrust reflex;
• Active interest in food and mouth opening in response to food presentation.

 

Nutritional Requirements of the Infant

Complementary feeding aims to supplement, not replace, breast milk, ensuring an adequate intake of essential nutrients.

Nutrient	Indications
Iron and Zinc	After six months of age, neonatal stores of iron and zinc tend to decrease. Therefore, early introduction is recommended of: Red meats, legumes, and fortified cereals as sources of iron and zinc; Combination with sources of vitamin C to enhance the absorption of non-heme iron.
Lipids and DHA	Lipids should constitute at least 35–40% of daily caloric intake, with particular emphasis on essential fatty acids, including DHA (docosahexaenoic acid), which is fundamental for: The development of the central nervous system and retina; Cognitive and visual maturation. Recommended dietary sources include oily fish, seed oils, and avocado.
Vitamin D	As breast milk does not provide sufficient amounts of vitamin D, prophylactic supplementation (400 IU/day) is recommended from birth and should continue during complementary feeding to support bone mineralization and proper immune function.

Table 1 – Key nutrients recommended during complementary feeding and their nutritional indications

 

Methods of Complementary Feeding

MOTHER-LED WEANING

The Mother-Led Weaning (MLW) approach, also known as traditional spoon-feeding or caregiver-guided weaning, consists of the gradual and structured introduction of pureed, mashed, or blended foods, with a planned progression toward more solid textures in parallel with the infant’s neuromotor and oropharyngeal maturation.

It is currently one of the most widespread approaches in pediatric practice due to its flexible and reassuring management for both parents and infants. It allows caregivers to:

• Introduce foods in a controlled manner;
• Monitor quantity, variety, and frequency;
• Adapt the diet to the infant’s nutritional needs or specific clinical conditions (e.g., reflux, allergies, metabolic disorders).

This method is particularly useful for parents who wish to play an active role in their child’s feeding process, gradually introducing new flavors and textures within a structured and secure framework, while respecting the infant’s individual developmental pace. MLW is valued for ensuring precise nutritional control and for facilitating the gradual adaptation of the infant to new foods.

 

 Advantages of the MLW Approach

1. Precise Control of Nutrient Intake

• • MLW enables caregivers to regulate the composition and quantity of foods with precision, optimizing the intake of essential macronutrients and micronutrients (proteins, iron, vitamins, etc.).
  • This is particularly beneficial for infants with clinical conditions such as anemia risk, food allergies, or metabolic disorders, where strict dietary monitoring is required.
  • Spoon-feeding also facilitates the gradual advancement of textures, reducing the risk of oral overload and allowing progressive adaptation of oral structures.

2. Enhancement of the Parent–Infant Relationship During Feeding

• • Guided weaning fosters reciprocal interaction and affective attunement between the caregiver and the child, strengthening attachment bonds.
  • The caregiver observes and responds appropriately to hunger and satiety cues, promoting a model of responsive feeding.
  • This context of attentive care improves the overall feeding experience, reduces mealtime anxiety, and helps prevent feeding-related behavioral issues.

3. Increased Feeding Safety

• • Direct caregiver supervision reduces the risk of choking or ingestion of inappropriate foods, particularly in early stages, as only textures suitable for the infant’s oral–motor development are offered.
  • Gradual progression and careful monitoring minimize adverse reactions and allow for the early detection of possible intolerances or allergies.

4. Facilitated Introduction and Monitoring of New Foods

• • Control over food composition allows for sequential and targeted introduction of foods, supporting the identification of potential food intolerances or allergic reactions.
  • It ensures nutritional variety and quality, including fortified cereals, proteins, vegetables, and fruits in balanced proportions.

5. Support for Oral Skill Development

• • Gradual spoon-feeding promotes coordinated oral function development, facilitating:
    • Control of tongue and jaw movement;
    • Adaptation to different consistencies, from liquid to semi-solid;
    • Acquisition of mature swallowing patterns essential for later chewing.

6. Controlled Sensory and Taste Learning

• • Through purees and blended foods, infants experience a gradual and reassuring sensory introduction to taste and texture, promoting acceptance of new flavors without overwhelming sensory input that could lead to rejection.
  • The progressive evolution of consistencies supports oral desensitization, beneficial in children with oral hypersensitivity or sensory processing difficulties.

7. Practicality and Adaptability for Caregivers

• • MLW is easy to implement for most families, fitting into daily routines with structured timing and minimal disruption.
  • Preparing homogeneous foods in small portions facilitates logistics and reduces food waste.

 

BABY-LED WEANING

Baby-Led Weaning (BLW), literally “weaning guided by the baby,” is an approach to complementary feeding based on infant self-feeding, in which the child, typically from around six months of age, actively participates in family meals.
Unlike the traditional spoon-fed model, BLW allows the infant to grasp, explore, and autonomously bring food to the mouth, provided the foods are safe in size, shape, and texture.

This method respects the infant’s neuromotor and sensory maturation, fostering an active, self-directed relationship with food guided by internal hunger and satiety cues within a supportive, non-coercive family environment.
A growing body of research highlights multidimensional benefits associated with BLW, encompassing neuropsychomotor development, the child’s relationship with food, and regulation of eating behavior.

 

Aspetti positivi dell’approccio BLW

1. Self-Regulation of Hunger and Satiety

BLW promotes the early ability of infants to self-regulate caloric intake in response to internal hunger and satiety signals.
This self-regulation, supported by responsive feeding practices, has been associated with:

• • Reduced risk of overfeeding;
  • Lower incidence of childhood obesity;
  • Establishment of long-term balanced eating habits.

2. Development of Fine Motor and Hand-to-Mouth Coordination

Through autonomous manipulation of food, infants practice essential motor skills, including:

• • Fine motor control (palmar grasp, pincer grasp);
  • Eye–hand coordination;
  • Oromotor control (bolus formation, chewing, swallowing).

These abilities are linked to improvements in executive functioning and functional autonomy, with positive implications for later cognitive and social domains.

3. Positive Multisensory Experience with Food

Self-feeding offers rich sensory stimulation, exposing infants to:

• • Diverse colors, smells, textures, and flavors;
  • Sounds related to chewing and handling food;
  • Varied temperatures and shapes.

This early exposure supports sensory tolerance and may reduce the risk of future food selectivity.

BLW emphasizes shared family meals, during which the child sits at the table with others, observing, imitating, and participating actively.

This practice:

• Encourages acquisition of healthy eating behaviors through observational learning (social modeling);
• Reinforces family routines, fostering belonging and emotional co-regulation during meals;
• Promotes a positive relational environment with fewer feeding conflicts.

 

INTEGRATED APPROACH

An integrated method combines elements of both MLW and BLW, offering the infant both pureed foods and those suitable for self-feeding. It is frequently applied in clinical settings for its flexibility and adaptability to individual developmental and nutritional needs.

 

Complementary Feeding and Neurobehavioral Development

During complementary feeding (CF), the infant develops the first skills of feeding autonomy, explores new textures and flavors, and consolidates habits shaped by the family environment.
This stage contributes significantly to the development of:

• Taste preferences, influenced by early exposure to a variety of foods;
• Emotional regulation, supported by a calm and responsive feeding environment;
• Executive functions, strengthened through the structure and rituality of mealtimes and social interaction.

Feeding conducted in an affective, positive climate that respects the infant’s cues, known as the responsive feeding approach, is associated with a lower risk of overweight and eating disorders in later childhood.

Postural, Oro-Motor, and Behavioral Maturation Cues

The introduction of complementary feeding should be individualized, considering not only chronological age (typically between 5 and 6 months) but also the achievement of specific neuromotor, postural, oral, and behavioral competencies, collectively referred to as feeding readiness.

According to the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) and the Italian Society of Pediatrics (SIP), a child may be considered ready to begin weaning when most of the following indicators are present:

1. Postural Control and Ability to Sit

The infant can maintain a seated position with minimal support (e.g., in a high chair), with stable head control and trunk alignment.
This ability is essential for:

• • Safe swallowing;
  • Proper food positioning within the mouth;
  • Prevention of aspiration episodes.

Lack of adequate postural control is a temporary contraindication to initiating complementary feeding.

2. Disappearance of the Tongue-Thrust Reflex

Between 4 and 6 months, the tongue-thrust reflex (which causes the infant to push out any foreign object from the mouth) tends to disappear.
This reflex maturation allows:

• • Acceptance of denser and solid foods;
  • Correct positioning of food on the tongue for voluntary swallowing.

3. Active Interest in Food and Mealtime Imitation

The infant attentively observes adults eating, shows curiosity toward food on the table, and tends to bring objects or foods to the mouth.
These are early signs of motivation to feed, marking a key step in:

• • The development of eating behavior;
  • Learning through imitation (modeling);
  • The onset of socialization during meals.

4. Ability to Grasp and Bring Objects to the Mouth

The infant demonstrates palmar or radial grasp, spontaneously picks up objects, and brings them to the mouth in a coordinated manner. This competence is particularly relevant for self-feeding approaches such as Baby-Led Weaning.

5. Oro-Motor Coordination and Onset of Gum Chewing

Even in the absence of teeth, the infant can “chew” with the gums, handling soft textures through coordinated jaw and tongue movements. The interplay between chewing, salivation, and swallowing is developing, and early exposure to varied textures supports neuromuscular adaptation.

6. Tooth Eruption (Not Mandatory)

Although dentition is not required to begin weaning, the eruption of the first incisors can facilitate the exploration of certain textures (biting, scraping, crushing). Typically, the first teeth emerge between 6 and 10 months, though timing can vary widely without pathological significance.

7. Ability to Communicate Hunger and Satiety

The infant begins to express clear cues of interest (mouth opening, leaning forward) and satiety (turning away, closing the mouth, looking aside). Respecting these signals is the foundation of responsive feeding, which promotes a healthy relationship with food and supports self-regulation of intake.

 

Food Safety During Complementary Feeding: Importance of Posture and Use of the High Chair

The introduction of complementary feeding (CF) marks a crucial phase in the infant’s nutritional and neuromotor development, but it also involves potential risks of choking and aspiration. For this reason, ensuring proper posture and a safe feeding environment is essential to prevent accidents and to promote a positive and protected feeding experience.

Seated Posture at 90 Degrees: An Essential Requirement

During complementary feeding, the infant should be positioned to maintain a stable upright posture, ideally with a 90° angle between the trunk and thighs.

Why is this posture important?

• Facilitates effective swallowing: The upright position allows for better control of the food bolus, reducing the risk of residue entering the upper airways.
• Prevents choking: In a supine or reclined position, the risk of aspiration of food or liquids increases substantially, as coordination between chewing and swallowing is compromised.
• Supports head control: Proper head alignment with the body allows for more coordinated and safer oral movements.
• Enhances orofacial muscle function: Upright posture optimizes activation of the muscles involved in chewing and swallowing.

 

 

Implementing proper safety practices during weaning is essential to prevent choking and to promote healthy, confident feeding development. Constant caregiver supervision is indispensable: an adult should always remain close to the child during meals, actively observing every action and ready to intervene immediately in case of respiratory or swallowing difficulties. It is essential to offer foods that are safe and developmentally appropriate for the child’s oro-motor abilities, favoring soft, easily chewable textures, cut into suitably sized pieces to prevent airway obstruction. Food selection must be adapted to the infant’s age and chewing/swallowing skills, in accordance with pediatric guidelines.

During meals, environmental distractions, such as noise or excessive visual stimuli, should be minimized to maintain the infant’s focus on the feeding act, thereby supporting a mindful and safe relationship with food. Finally, specific caregiver training in airway obstruction first-aid maneuvers is an indispensable preventive measure, enabling rapid response in the event of choking and significantly reducing the risk of severe outcomes.