CMPA can occur in breastfed babies but it is much less common than in formula fed babies. 0.5% of exclusively breastfed babies show reactions to cow’s milk protein compared to 2-7.5% of formula fed babies. It is thought that immunomodulators present in breast milk and differences in the gut bacteria of breastfed and formula fed infants may contribute to this.
The level of cow’s milk protein present in breast milk is 100 000 times lower than that in cow’s milk. Not all breastfeeding mums need to restrict dairy products from their diet, as some babies with CMPA only react to dairy products given to them in their own diet.
In order to prove/disprove a delayed type allergy to cow’s milk of an exclusively breast fed baby, a trial elimination of dairy products (for mum) for 2 to 4 weeks is recommended and then a reintroduction to see if symptoms return (or not). The MAP guideline has an excellent algorithm to explain this (there is a link on the Allergy UK website).
If a mum needs to exclude dairy products form her diet, it is really important that mums are supported to help them maintain a good nutritional intake to support breastfeeding for as long as they wish to continue, preferably until 2 years of age as recommended by the World Health Organisation.
Fortified alternatives to dairy/soya milk, yoghurt and cheese can be very useful for breastfeeding mums to meet her nutritional requirements. However, she may need supplementation if she cannot meet her nutritional requirements of 1250mg calcium and 10ug vitamin D per day (ask a Registered Dietitian for help with this)
Should a breastfeeding mum exclude other foods from her diet, such as soya and/or egg?
This is a very important question and not easily answered! The MAP guideline recommends that if a breastfeeding mum has trialled an exclusion diet for 4 weeks and there has been no obvious improvement to symptoms, but a food allergy is still suspected, then egg should also be excluded from mum’s diet. However, this requires careful consideration and a referral to an allergy specialist team.
Some centres advise against using soya milk and yoghurts to replace dairy, but allow small amounts of soya such as soya flour in bread (most breads in the UK contain soya flour so it is quite difficult to eliminate soya completely).
Guidance from a Registered Dietitian is recommended.
