What is formula feeding and what are its types?

What is Formula Feeding?

Formula feeding is the practice of providing infants with industrially produced breast milk substitutes (infant formula) as their primary or sole source of nutrition, typically used when breastfeeding is not possible, suitable, or solely adequate. 1

Definition and Composition

Formula feeding involves using manufactured products designed to mimic the nutritional composition of breast milk as closely as possible. 1 These formulas are highly regulated by government agencies, as they serve as the sole source of nutrition for growing and developing infants. 2 All ingredients must be considered "generally recognized as safe" by regulatory authorities. 2

Types of Infant Formula

Standard Formulas

For healthy term infants who cannot be breastfed, standard iron-fortified cow's milk-based formula is the recommended choice. 3, 4 This is the evidence-based alternative when breast milk is unavailable. 3

• Standard cow's milk-based formula: The most common type, available in standard dilutions of 19 or 20 calories per ounce 2
• Organic formulas: A subcategory of standard cow's milk-based formulas 2
• Iron-fortified formulas: Must be used to prevent iron deficiency anemia, which is common when non-fortified options are used 3, 4

Formulas for Intolerance

These products are marketed for signs and symptoms of intolerance and include: 2

• Lactose-modified formulas: With reduced lactose content 2
• Partially hydrolyzed protein formulas: Though the American Academy of Pediatrics recommends against using these for prevention of allergic disease or colic due to insufficient evidence of benefit 3
• Formulas with added probiotics 2
• Formulas with added rice starch 2

Specialized Medical Formulas

For confirmed cow's milk protein allergy, extensively hydrolyzed casein formula is the first choice, with elemental (amino acid-based) formula as the second choice if the hydrolyzed formula is not tolerated. 3

Specialized formulas exist for specific medical conditions: 2

• Extensively hydrolyzed formulas: For confirmed cow's milk protein allergy 3
• Elemental (amino acid-based) formulas: For food protein-induced enterocolitis syndrome (FPIES) or when extensively hydrolyzed formulas are not tolerated 3
• Premature infant formulas: For preterm babies 2
• Formulas for gastrointestinal disorders 2
• Formulas for disorders of fat metabolism 2
• Formulas for renal insufficiency 2

Soy-Based Formulas

The American Academy of Pediatrics recommends against the use of soy-based formulas for prevention of allergic disease or colic due to insufficient evidence of benefit. 3 Soy formulas are based on soymilk rather than cow's milk. 1

Formula Preparation Forms

Formulas are available in three forms, each with distinct advantages and disadvantages: 2

• Ready-to-feed: Requires no preparation but is more expensive 2
• Liquid concentrate: Requires mixing with water 2
• Powder: Most economical but requires careful preparation 2

Each manipulation required for feeding introduces another opportunity for bacterial contamination, making proper preparation technique critical. 2

Critical Safety Considerations

Whole cow's milk should not be introduced before 12 months of age, as early introduction leads to iron deficiency anemia and increases the risk of cow's milk protein allergy. 3, 4

Vitamin D supplementation (400 IU daily) is required for all breastfed infants and those consuming less than 28 ounces of formula per day. 3, 4

Avoid switching formulas frequently based on normal infant fussiness or minor spit-up, and avoid using hydrolyzed or soy formulas as a preventive measure without medical indication. 3

Monitoring Requirements

Growth parameters (weight, length) should be monitored regularly in all infants, especially those on specialized formulas. 3, 4 Infants on specialty formulas should be monitored closely by medical professionals. 2

Environmental Context

Formula feeding has a significantly greater environmental impact than breastfeeding, with approximately 48% higher carbon footprint. 5 Infant formula's global warming potential is 2.02 kg CO2 eq per kilogram versus breastmilk's 1.58 kg CO2 eq. 5 The water footprint for 1 kg of commercial milk formula use is 699 liters. 5