Infant formula

In New Zealand, infant formula and follow-on formula must comply with the requirements of the Australia New Zealand Food Standards Code.³ This code contains standards for the composition of infant formulas so they meet the nutritional needs of a growing infant.

Infant formulas differ depending on where the protein in the formula is derived. Infant formulas available in New Zealand are based on cows' milk, goats' milk and soy protein.

Cows' milk-based formula is routinely recommended for feeding an infant who is not breastfed

Cows' milk-based formula is recommended as the first choice for feeding healthy infants who are not fully breastfed.⁴

The protein in cows' milk-based formula is derived from cows' milk. The carbohydrate component is generally provided by lactose, corn syrup solids and corn maltodextrin. Vegetable oil blends usually provide the fat component.

Whey and casein are the two types of protein present in breast milk and cows' milk. Breast milk contains more whey than casein and this ratio changes over the course of lactation.¹ Infant formulas vary in their composition and may be whey or casein dominant.

There are many different commercially available cows' milk based formulas which are readily available from supermarkets and pharmacies. Some examples are S-26, Nurture Starter, Novalac 1, Nan 1 Gold Protect and Karicare Gold 1. Cows' milk formulas appropriate for infants aged up to six months often have "1" or "starter" in their name.

Regular cows' milk is not suitable for infants aged less than one year

Soy-based formula should not be used routinely

There are only a few indications for the use of soy-based infant formula in place of cows' milk-based formula. These indications are: infants with galactosaemia, a rare inherited condition where infants are unable to metabolise galactose to glucose, or vegan infants who are not breastfed.

The protein in soy-based infant formula is derived from refined soy protein isolate. Soy-based formula is free of lactose and cows' milk protein.¹ However soy-based formula is not recommended for cows' milk allergy as 10-14% of infants with allergy to cows' milk protein will also have a soy protein allergy (see hydrolysed formula for recommendations).^{2, 4}

Soy-based formula is not designed for or recommended for pre-term infants.¹⁴

Soy-based formula needs to meet defined standards for infant formula and requires fortification with the amino acid methionine. Soy-based formulas contain high concentrations of phytate, aluminium and phytoestrogens, for which the long term effects are unknown.⁴ Examples of soy-based formula are S-26 Soy and Karicare Soya.

Goats' milk-based formula

Goats' milk formula is not suitable for infants with lactose intolerance, galactosaemia or allergy to cows' milk protein.¹ It contains lactose and has cross-reactivity with cows' milk protein, which means that infants allergic to cows milk are also likely to be allergic to goats milk. The likelihood of cross-reactivity between cow and goat milk is approximately 90%.⁵

Specialised formula and additional ingredients

Hydrolysed formula for cows' milk protein allergy
Partially or extensively hydrolysed formula contains cows' milk protein that has been broken down into peptides. In general, the more extensive the hydrolysis of the protein, the less likely it is to cause an allergic response.¹ Extensively hydrolysed formula (e.g. Pepti Junior) should be used for the treatment of children who have diagnosed cows' milk allergy.⁶ If allergic symptoms persist a free amino acid formula (e.g. Neocate) is recommended.^4,7

There is some evidence for the use of hydrolysed formula for high risk infants (infants with at least one first-degree relative - parent or sibling - with diagnosed allergic disease) to prevent or delay the development of atopic dermatitis. Extensively hydrolysed formula may be more effective in preventing allergies than partially hydrolysed formula.^1,7 The recently published German Infant Nutritional Intervention study confirms a preventive effect of hydrolysed infant formula persists until age six years.⁸ More research is needed into whether these benefits extend into late childhood and beyond.

Hydrolysed formula carries a significant cost and referral to a paediatrician or allergy specialist is advised to obtain funding for them under special authority.

Probiotics, prebiotics and long chain polyunsaturated fatty acids
Probiotics, prebiotics and long chain polyunsaturated fatty acids are added to infant formula to make them more closely resemble breast milk.

Probiotics are live bacteria that colonise the gastrointestinal tract. When administered in adequate amounts they may improve gut barrier function and host immune response. There are many different strains of probiotics but the most common are Bifidobacterium or Lactobacillus species. Breastfed infants have been shown to have more Lactobacilli and Bifidobacteria in their intestines than formula fed infants.

Prebiotics are food ingredients (usually oligosaccharides) that are resistant to digestion in the small intestine. They are fermented by beneficial bacteria in the large intestine selectively stimulating the growth of non-pathogenic bacteria in the colon such as Lactobacilli and Bifidobacteria. Breast milk contains oligosaccharides which have been shown to demonstrate a prebiotic effect in infants.⁹

Two systematic reviews in 2007 found that there was insufficient evidence to recommend the use of probiotics or prebiotics in infant formula for the prevention of allergic disease or food reactions.^{10 11}

Long chain polyunsaturated fatty acids (LCPUFAs) are present in breast milk. LCPUFAs are important components of the phospholipids present in the retina and the brain and are also integral structural components of all cells in the body. Almost half the high lipid content of the brain is LCPUFAs. Since the mid 1990s LCPUFAs, have been the focus of much research. Early research suggested that infants fed a continuous supply of LCPUFAs, from either breast milk or a supplemented formula, may have improved visual functioning.¹² For this reason LCPUFAs are now added to some infant formula. Although LCPUFA-supplemented infant formula seems safe, a 2007 Cochrane Systematic Review found that the results of most of the well conducted randomised controlled trials, have not shown beneficial effects of LCPUFA supplementation on the physical, visual and neurodevelopmental outcomes of infants born at term.¹³

Indications for switching formula

Generally there is limited evidence for switching formula when infants experience symptoms such as vomiting, spilling, crying, diarrhoea or constipation.

• Lactose intolerance - lactose-free (e.g. De-lact, S-26 LF ) and reduced lactose cows' milk formula (e.g. Novalac AC or AD) can be used when the elimination or reduction of lactose from the diet is required. However lactose intolerance is likely to be dose dependent and only rarely does lactose need to be totally eliminated from the diet. Therefore the use of lactose-free soy-based formula for this indication should be restricted.¹⁴
• Diagnosed cows' milk protein allergy - An extensively hydrolysed protein formula (see above) should be used for infants with cows' milk protein allergy. Soy-based formula is not recommended in infants with allergy to cows' milk protein.¹⁴
• Acute gastroenteritis - most previously well infants can be managed after initial rehydration with continued use of breast milk or standard cows' milk formula.
• Colic, regurgitation or prolonged crying - Counselling parents about the cause and duration of colic may have more value than switching formula. There is no evidence for soy-based formula for the prevention or management of infantile colic, regurgitation or prolonged crying.⁴
• Prevention of allergies - There is some evidence for using hydrolysed formula for preventing allergies.⁸ Routine use of soy-based formula has no proven value in the prevention of atopic disease in healthy or high-risk infants.

Follow-on formula

Follow-on formula is designed for infants from 6-12 months. It is fortified with additional nutrients such as iron. However if an infant is thriving on the standard infant formula and eating a well-balanced complementary diet, switching to this formula is not usually necessary.²

Regular cows' milk is not suitable for infants aged less than one year. For infants weaned from breastfeeding after they are six months old and before 12 months old a follow-on formula may be an appropriate choice.