In most cases, a cow's milk based formula will be recommended for your baby. However, in the last decade, many more women have chosen to use soy-based formulas for their babies, at their own discretion. The move towards soy based milks has probably evolved because of the misperception that it is 'better' than cows milk, or that it may help colic, or that the baby is unsettled and possibly intolerant, or allergic to the cow's milk formula. The research to date does not support these claims and caregivers usually only recommend soy milk formula in certain circumstances, for example if the baby has a
metabolic disorder such as
galactosaemia, or the baby truly has a cow's milk intolerance.
In reality, the percentage of babies allergic to cow's milk formula is about 1.8 to 3.4%. Some babies are also allergic to soymilk formula (about 0.5% to 1.1%). Babies on both cow and soymilk can also develop irritations of the bowel and may need to have the formula changed if this happens. When comparing babies having cow's milk formula with babies having soymilk formula there is no significant differences in the amount of babies who experience colic, skin disorders (such as eczema) or allergies.
Soy based formulas are very high in aluminium (600 to 1300 ng/ml, compared to 4 to 65 ng/ml in human milk). Aluminium competes with calcium in the body to get to the bones first, and can affect bone growth and the density of the bone, even if the person takes extra calcium supplements. So far it has been found that babies born at
term do not appear to be affected by this, but premature babies weighing less than 1,800 grams have been found to have less weight gain and less growth in their length, compared to premature babies fed cow-based formulas. Therefore, soy formula for very small premature babies is not generally recommended.