Adapted Milk Formulas (AMF): Safety, Classification, and Strategies for the Selection of Prophylactic and Therapeutic Nutrition

Mother’s milk is the sole source of all necessary nutrients for the complete growth and development of an infant. From birth as the child matures, breast milk adapts according to the child’s needs at any given time.

In addition to the primary sources for energy and physical development (proteins, fats, and carbohydrates), breast milk contains many bioactive substances and living cells that are unique to each mother and baby and cannot be fully reproduced in a laboratory. Moreover, the process of breastfeeding helps the child’s nervous system adapt to external stress and form a psychological attachment to the mother.

However, there are many cases where breastfeeding (BF) is not possible for various reasons. The refusal to breastfeed should be justified and considered a “last resort.” If the family faces the impossibility of breastfeeding or using donor milk, adapted milk formulas come to the aid of parents.

Definition

Infant formula is a substitute for human breast milk, manufactured from cow, goat, or other mammalian milk, meeting the nutritional needs of infants from birth until the child fully transitions to complementary feeding.

AMF Safety

When switching to bottle feeding, parents wonder about the safety of feeding their child with the chosen formula, whether it meets all the needs of the infant’s growing body, and what long-term consequences the choice of a particular formula may entail.

Control over the quality of milk formulas is a complex multi-level system regulating the production of AMF at international and regional levels, at the manufacturer level, and through post-marketing data collection.

The global scientific basis for regulation is the Codex Alimentarius.

The Codex Alimentarius Commission, established by the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO), develops food standards, guidelines, and texts aimed at protecting consumer health and ensuring fair trade practices globally. In more than 160 countries that are members of Codex Alimentarius, the majority of the world’s population resides.

Codex Alimentarius (FAO/WHO) establishes the following:

• Minimum and maximum nutrient levels;
• Requirements for the safety, purity, and quality of ingredients;
• Principles of risk assessment.

It is used as a reference standard by the WHO and most countries worldwide. It does not have direct legal force but underlies national legislation.

Thus, any infant formula available for sale is a completely safe product meeting global standards for child nutrition.

Classification of Adapted Milk Formulas

In today’s world, the choice of milk formulas is vast and diverse. For simplicity of understanding, they can be classified by the following criteria:

By nutritive value and age

• Pre-formulas: for premature and low-birth-weight infants in early periods;
• Stage 1: for infants from 0 to 6 months;
• Stage 2: for infants from 6 to 9–12 months;
• Stages 3 and 4: for children over 1 year.

As the child’s nutrient needs change with maturation, AMF stages are distinguished by the ratio of proteins, fats, carbohydrates, and nutritional value.

By function

• Standard: for healthy children;
• Prophylactic: for the prevention of functional disorders and children from risk groups (hypoallergenic, antireflux, etc.);
• Therapeutic: during diet therapy for diseases.

In some cases, formula feeding may be complicated by both functional digestive disorders and food allergies. In such cases, the choice of formula will favor prophylactic or therapeutic.

By the nature of protein

• Formulas based on animal protein (cow’s, goat’s);
• Formulas based on plant protein (soy, rice).

For infants under 6 months, the first formula can only be based on animal protein. Formulas based on plant protein can be an alternative in cases of animal protein intolerance (e.g., cow’s milk protein allergy) and an absence of reaction to plant protein.

By the degree of protein hydrolysis

• Formulas based on whole protein;
• Formulas based on partial protein hydrolysis (hypoallergenic);
• Formulas based on complete protein hydrolysis;
• Amino acid formulas.

Any foreign protein, when consumed in large quantities by an infant, can lead to sensitization and allergy. Therefore, AMF proteins can be partially or fully broken down if they cannot be absorbed by the body in their whole form.

By lactose content

• Containing lactose;
• With reduced lactose content;
• Lactose-free.

Milk sugar (lactose) is the primary source of energy and substrate for the development of the child’s nervous system. However, due to primary or secondary lactase deficiency, the level of lactose for the child may be reduced by selecting the appropriate formula.

AMF classification allows the physician to assess the condition of the child needing artificial feeding and to select the formula option that will address the energy need, provide comfortable digestion, and prevent feeding disorders.

Additional substances enriching AMF

Certain components of breast milk, such as immune cells, antibodies, microbiome, and regulatory molecules, cannot be synthesized industrially and added to the formula. However, modern scientific society and manufacturers strive to improve formula components and bring their composition closer to that of breast milk.

Prebiotics and probiotics play an important role for the body.

Prebiotics are substances or molecules that promote the formation and growth of healthy microflora, with bifidobacteria playing a major role for infants.

Probiotics are live microorganisms that, when consumed, help normalize the composition of microflora.

Prebiotics include human milk oligosaccharides.

Human milk oligosaccharides are unique and perform the following tasks and functions:

• Remaining partially undigested, they serve as a substrate for the growth of bifidobacteria, forming a healthy microbiome;
• The growth of bifidobacteria helps reduce the number of pathogenic bacteria in the infant’s gastrointestinal tract;
• Interacting with the immune system cells, they ensure improved immune function of the body.

Several types of human milk oligosaccharides have been synthesized on an industrial scale, which enrich AMF. It has been proven that human milk oligosaccharides positively affect the functions of the infant’s gastrointestinal tract.

Probiotics include a Lactobacillus species, L. Reuteri. Scientific data on the effects of Lactobacillus reuteri on the frequency of infant colic are contradictory; however, studies exist demonstrating a reduction in pediatric consultations for infant colic in children receiving specific strains of Lactobacillus reuteri.

Criteria for formula selection

Choosing a formula for a healthy child is usually not difficult for a pediatrician. Preference for such an infant is given to a formula based on cow’s milk protein of stage 1 or 2, depending on the child’s age.

Once the child begins to receive formula, it is necessary to evaluate the adequacy of the choice based on the following criteria:

• Stable adequate weight gain (300-800 grams per month depending on age);
• Regular stool (from 4 times a day to once every 3 days);
• Stable general condition of the child.

Conditions that require a review of the formula choice include the following:

• Marked child distress during or immediately after feeding;
• Abundant regurgitation from 1/3 to the full volume of feeding;
• Lack of weight gain;
• Increased gas production and difficulty in passing intestinal gases;
• Loose, foamy stools with a sour smell (may be a sign of lactose intolerance);
• Blood streaks in the stool (may indicate an allergy to cow’s milk proteins or an anal fissure);
• Dense, hard stool injuring the anus;
• Absence of stool for more than 3 days with significant child discomfort;
• Evident skin changes (widespread atopic dermatitis, urticaria).

In the above cases, the physician evaluates the necessity of switching to a preventive or therapeutic formula.

Typical preventive formulas

Hypoallergenic formulas

A hypoallergenic formula is an AMF based on partially hydrolyzed (broken down) cow’s milk protein. It is used in children at risk for allergic reactions, like cases of cow’s milk protein allergy or severe atopic dermatitis in the family or older children. It cannot be a therapeutic formula for identified conditions in infants.

Anti-reflux formulas

Reflux is the backward flow of liquid food (in this case) from the stomach to the esophagus and throat. In all infants, the sphincter between the stomach and esophagus is weak, so mild regurgitation in infants is normal. However, in some cases, severe regurgitation can lead to decreased weight gain rates and respiratory complications.

In such cases, an anti-reflux formula is prescribed, which contains a safe thickener—carob bean gum or starch—that helps reduce the backflow of the formula and aids its further progression in the gut.

Fermented milk formulas

Due to the content of lactic acid bacteria, their metabolites, and partially hydrolyzed protein, fermented milk formulas help improve digestion by normalizing microflora, reduce gas production intensity, and promote stool normalization, thus reducing constipation. It cannot be the main formula; it must be used in combination with non-acidified milk formulas.

Comfort line formulas

In these formulas, the main protein is partially hydrolyzed to ease digestion, and the reduced lactose content decreases the load on the child’s enzymatic systems. The fats in the Comfort line formulas ensure the formation of a soft stool. The formula is used as the main formula for children prone to functional digestive disorders.

Pre-formulas

Pre-formulas are intended for premature and low-weight children from the first days of life to ensure rapid weight gain. Unlike standard formulas, they contain a high amount of protein and may be used for a limited period or prescribed based on indications for low weight gain rates.

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Typical therapeutic formulas

Lactose-free formulas

Prescribed for children with primary or secondary lactase deficiency (LD). In cases of secondary LD, a transition to low-lactose or standard formula may subsequently occur.

Formulas based on complete protein hydrolysis

Prescribed for children with cow’s milk protein allergy, severe atopic dermatitis, and also for children who have undergone gastrointestinal surgery or those with protein-energy malnutrition. Complete hydrolysis formulas can be lactose-free or contain lactose.

Amino acid formulas

Amino acid-based formulas are prescribed for children with severe cow’s milk protein allergy, polyvalent food allergy, malabsorption, severe protein-energy malnutrition, and certain other digestive-related conditions.