Author: Vicki Martin | - Dietitian | Auckland New Zealand


Infant formulas are necessary for babies who are not breastfed and those who are being weaned off the breast. This article provides a thorough guide to infant formulas on the market including cow, goat, and soy milk-based formulas.

It's your choice

Every woman must make her own personal decision on how to feed her infant. There should be no sense of failure in deciding to bottlefeed. For a variety of physical, practical, and emotional reasons it may be a sensible decision to make.

One does not need permission from a health professional to bottlefeed, however, a knowledgeable and supportive medical practitioner, plunket nurse, midwife, dietitian, or pharmacist is best to be consulted regarding the most suitable type of formula for your infant.

The final decision may rest with your infant. Their tastes, appetite, digestive and growth capabilities must not be ignored.

Caution: Infants should not be fed plain cow, goat or soy milks until one year of age. These milks lack a variety of essential nutrients needed for physical and mental development and do not match the complexity of breast milk nutrients. These milks are high in protein and sodium (high renal solute load) which place a strain on immature kidneys and increases the risk of dehydration.

Infant formulas are modified forms of these milks which are developed to be as similar to human milk as is possible. Your infant may need up to three different milk formulas in their first year to approximate the composition of breast milk at different growth stages.

Become a label expert

Even if you are planning to breastfeed it would be wise to start discussing and investigating appropriate formulas before your baby's birth so that you will be well prepared in case of need.

Develop your knowledge of label ingredients and ways of mixing and sterilising. Ring the customer services departments of formula companies for any information you require.

Differences in infant formulas

  • Age group - certain formulas are more suited to infants under the age of six months and others, usually called 'follow-on' or 'progress', suit older infants. The composition of these formulas is altered to suit the developing digestive system and the greater requirements of various nutrients. Young infants should not be given older infants' formulas as they may cause dehydration due to the increased solute load.
  • 'Follow-on' and 'Progress' type formulas are needed for infants 6 months and older. They contain more protein, iron, calcium, and other essential nutrients necessary for healthy growth.
  • Whey based (or 'premium' formulas are the most similar to human milk protein composition. New and premature babies should be given these for the first 8 weeks of life as they will find it easier to digest. Whey formulas put less strain on the kidneys (low renal solute load) therefore reducing the incidence of dehydration.
  • Casein based formulas - Casein is a larger protein molecule and it forms curds that are more slowly digested. It satisfies hungry babies and is much more economical. It may cause digestive discomfort or constipation in some infants due to the longer digestive time.
  • Lactose is the natural milk sugar found in breast, cow, and goat milk. Some infants have trouble digesting this and it may cause bloating, diarrhoea, and windiness. The alternatives are soy milk formula or casein-based lactose-free formulas (although Wyeth S26 is whey-based). The sweeteners in lactose free formulas are usually glucose and corn syrup. Your infant may benefit from these formulas for a short period of time if they have had a temporary digestive infection.
  • You may need to use goats or soy milk if you have a family history of allergies especially eczema or asthma or if your infant develops these problems. Try one of these formulas for a month to see if your infant's symptoms improve.
  • Goats milk formula forms a softer curd and has smaller fat globules than cows milk which makes it more digestible for some infants.
  • Spilling - specialist reflux formulas are available for all stages of infant growth if this is a concern. They tend to be thicker formulas which stay in the stomach and are less likely to splash back into the oesophagus or mouth. Thickening agents may be pre-cooked corn or rice starch which are usually absorbed into the digestive system. Carob bean gum is fermented by intestinal flora and may cause distension or discomfort. Reflux formulas are usually casein-based and have lower fat levels as this tends to reduce regurgitation.
  • Specialist hydrolysed protein formulas are available for infants who show allergies to all formulas and breast milk. A government subsidy is available if the formula is recommended by a medical practitioner.



  • The basic composition for milk formulas is either cow, goat, or soy protein. This vital nutrient is necessary for growth.
  • These proteins contain eight essential amino acids. Infants require two extra amino acids for growth - arginine and histidine. Infant formulas may have these added. Casein based amino acids are more similar to those found in breastmilk.
  • The two main types of protein found in goat and cows milk are whey and casein. Breast milk is whey dominant (a ratio of 60:40), cows milk is casein dominant (a ratio of 18: 82). Infant formula developers alter the ratio to simulate breast milk.


  • Fat is an essential part of any milk formula. It provides 50% of the daily energy requirements and it is necessary for the infant to acquire fat stores to insulate and cushion their developing body.
  • Fats also carry essential fatty acids and fat-soluble vitamins along with providing a full and satisfying feeling in the infant's stomach. Formulas usually contain a combination of vegetable and animal fats to give a ratio of unsaturated to saturated fats similar to breast milk.
  • Greater saturated fat content (which may be animal or vegetable sourced) may reduce calcium absorption. Breast milk contains 44% saturated fats, 17.1% polyunsaturated fat, and 38.9% monounsaturated fat.
  • If you are changing formulas it is best to keep to a similar combination of fats as your previous formula to prevent digestive problems.
  • Long-chain polyunsaturated fatty acids (LCPs) are recent additions to many formulas. Different types of LCPs are Omega 6, Omega 3, AA, and DHA. These are essential for good vision and brain development. LCPs are particularly beneficial in the first three months of life, after this the digestive system can manufacture its own. Their sources are usually fish oil or refined microalgae. The latter may be more digestible for some infants.
  • Taurine and carnitine are amino acids added to formulas to improve fat digestion.

Other ingredients

  • Iron is an essential mineral necessary for a healthy immune system and good brain development. Unfortunately it is difficult to absorb. You will find it in higher quantities in 'follow-on' and 'progress' formulas for older infants. Iron absorption is improved with the addition of Vitamin C.
  • Lactose is the natural sugar found in cow, goat, and breast milk. It assists in the absorption of calcium and feeds beneficial bacteria in the digestive system which aid in healthy immunity.
  • Calcium and phosphorus in the correct amounts are important for the proper formation of bones, teeth, and blood clotting. Vitamin D assists in the absorption of calcium.
  • Nucleotides are recent additions to infant formulas. Naturally
    occurring in breastmilk, they are specialist types of protein. They seem to enhance the immune system, maintain the balance of cholesterol, improve iron absorption, assist in LCP use in the body, help maintain a healthy beneficial bacteria population, and improve digestion.
  • Betacarotene is a precedent of Vitamin A. It is necessary for healthy immunity and good vision.
  • Other vitamins and minerals are added in quantities similar to breast milk.

Other Concerns

  • Vegetarians - Check with individual infant formula companies to make sure there are no ingredients which you may find objectionable.
  • Soy Infant Formula - GE - check with individual infant formula
    companies as to whether their products contain genetically modified soybeans. In the future there may be mandatory labelling.
  • Soy Infant Formula - Phytoestrogens - Historically and culturally (i.e. in Asia) it has been shown that infants grow and develop normally and have normal metabolic functions on soy products. However, it would be wise to avoid use for infants with personal or family histories of thyroid disorders. Isolated cases of soy-fed infants with these disorders have had their symptoms resolved on withdrawal of formula. Modern soy formulas now include iodine to prevent the possibility of hypothyroidism.
  • Soy Infant Formulas should be fortified with methionine an essential amino acid.
  • Soy Infant Formula contains no lactose, so is usually sweetened with corn syrup or sucrose. The latter may cause dental decay.

Formula brands available in New Zealand:

Type 0-3 months (with LCPs) 0-6 months 6-12 months
Premium (whey based)S26
Gold Karicare First
Karicare Infant Nuture
Premium Enfalac
S26 Progress*
Karicare Follow-on
Nurture Follow-on*
Economy (casein based)SimilacSimilac Gain
Karicare Soy
GoatKaricare GoatKaricare Goat Follow-on
Specialist: RefluxEnfalac AR*Enfalac AR* Follow-on
Specialist: Lactose-Free

* Casein dominant formulas

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