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Bottle feeding - soy infant formulas

Soy; infant; formula; ;

Where a baby is unable to have cow's milk because of cow's milk allergy or lactose intolerance soy infant formulas may be suggested instead.

Contents of this topic

Soy infant formulas are made from soybeans and do not contain any animal products. They don’t have lactose in them (a natural sugar in cow’s milk and breastmilk).

Like other infant formulas they are specially prepared to meet the food needs of babies.

Soy milks or soy drinks from the supermarket are not a complete food. These must not be used for infants.

Soy infant formulas

  • These are different from the usual cow's milk based infant formulas in two ways:
    • they do not contain cow's milk proteins
    • they do not contain lactose (milk sugar).
  • Thus they can be tried for babies who cannot have cow's milk because 
    • they are allergic to cow's milk protein- however up to 60% of babies who are allergic to cow's milk protein will also react to soy protein - so it may be better to use a special low-allergy infant formula. A doctor will advise you about this. There is more about this in the topic Cow's milk allergy
    • they are lactose intolerant - although cow's milk based lactose free formula is usually recommended for this. There is more about this in the topic Lactose intolerance in babies 
  • Soy formulas do not prevent allergy. If a baby at risk of allergies (based on family history) is not breastfed, it is better to use a HA (hypo-allergenic) cows' milk formula.
  • Soy formulas have all the nutrition a baby needs for good health and growth.
  • Soy formulas and soy milks have more aluminium than cow's milk and cow's milk formulas. This is because the soy bean contains aluminium naturally, so it is unlikely to change. However this is considered to be harmless for normal babies.
  • There have been concerns about hormones in soy formulas and milks. It is believed that the levels of these hormones are too low to cause problems. 
  • It is also possible that babies fed on soy may have lowered immunity. 

For these reasons it is best to use the normal cow's milk formulas unless there is a medical reason to change.

  • Premature babies are at more risk of problems with soy formula, so they should not be used before the baby reaches his due date.

Reasons soy infant formulas may be used

These include:

  • If you want your baby to be a vegan (so don’t want him to have a cow’s milk formula).
  • If your baby has a problem with lactose (lactose intolerance). BUT there are other formulas you can use for this problem, and soy formula may not be the first choice. So it’s best to speak to your doctor before changing formula.

Other choices for medical conditions

  • If you have been advised to use soy infant formulas and you do not want to, talk to your doctor to see if there is another option.
  • There are some cow's milk infant formulas for lactose intolerance. Your doctor can advise you about these.
  • Special low allergy infant formulas can be given for cow's milk protein intolerance. These are also lactose free, but they are very expensive without a prescription.

Soy milks that are not soy formulas

Reasons why soy milks or soy drinks (that are not specially prepared for babies) must not be used for babies:

  • They are not a complete food.
  • They have too much protein and minerals.
  • Soy protein is not a first class protein - it is missing essential amino acids which are important for growth and health (these are added to soy baby formula).
  • They don't have enough iron, or enough of some vitamins.
  • Most soy milks don't have much calcium, although some have added calcium.
  • They have no Vitamin B12 unless this has been added.

Full fat calcium fortified soy beverages are suitable for use after 1 year of age as part of a mixed diet.

Soy and phyto-oestrogens

Soy products contain chemicals which act like hormones. They are called phyto-oestrogens. It is not known if these have any effects on children. The levels are probably too low to have any effect.

Babies have been given soy formulas from birth for many years with no known ill effects, and soy may well have health benefits overall. However it is recommended that soy formula only be used for babies when there is a real medical need. It is unlikely that there would be any problem with using soy as part of a good mixed diet in an older child.

A Paediatric Policy Statement by the Australasian College of Physicians

The 'Soy Protein Formula' Policy includes the following points:

  • recommends that infants under one year who are not breastfed should be fed an infant formula, not a soy or dairy based milk marketed for older children or adult consumption.
  • notes that soy formula has not been shown to be effective at preventing the development of atopy in ‘at-risk’ children, and may worsen atopic illness with prolonged use. (Note: atopy means health problems such as eczema, hayfever and asthma.)
  • recommends the use of extensively hydrolysed infant formula in infants with proven cow’s milk allergy or cow's milk protein intolerance who are not breast fed.


Netting M 'Are soy beverages suitable for 1-2 year olds?' Nutrition Department, Women's and Children's Hospital, South Australia.  

Royal Australasian College of Physicians 'Paediatric Policy - Soy protein formula'  2006

More information

The full Infant Formula Booklet produced by Women's and Children's Health Network is available for downloading from the Nutrition department. 

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The information on this site should not be used as an alternative to professional care. If you have a particular problem, see a doctor, or ring the Parent Helpline on 1300 364 100 (local call cost from anywhere in South Australia).

This topic may use 'he' and 'she' in turn - please change to suit your child's sex.

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