Soya infant formulas are recommended for use on medical advice. They are formulated to be suitable for infants who cannot tolerate cows' milk because they are either allergic to cows' milk protein and/or are unable to digest the carbohydrate (lactose) in cows' milk.

Current Department of Health advice is that soya infant formulas should not be the first choice for the management of infants with proven cow's milk sensitivity, lactose intolerance, galactokinase deficiency and galactosaemia, but accept that there may some circumstances for which soya infant formulas may be given, e.g. to infants of vegan parents who are not breastfeeding and to infants who may find the alternatives unacceptable.

Soya infant formulas are nutritionally similar to cows' milk-based formulas except that the protein comes from soya and the lactose is replaced by other permitted carbohydrates. The protein used in soya infant formulas is an extract of the soya bean which has a very high protein content.

The carbohydrates used in soya infant formulas are usually glucose syrups - a particular type of starch made up of polysaccharides of varying chain length, maltose and glucose. The total amount of carbohydrate is controlled by law in order to provide similar levels of sweetness to breastmilk and cows' milk formulas. Glucose syrups are the most suitable alternative to lactose as they are well tolerated and easily digested by infants. They are no more likely to cause dental caries than the lactose in cows' milk based formulas.

Soya infant formulas also contain natural plant oestrogens called phytoestrogens. The biological effects of phytoestrogens in soya infant formulas are currently the subject of much research but there is no evidence of adverse effects in humans. Read our IDFA Briefing Paper.

For further information about the Department of Health's advice click here.