Infant food allergies & cow's milk allergy

Yes, breastfed babies can react to cow's milk proteins that pass through breast milk. The standard approach, as outlined in the iMAP milk allergy guideline, when CMPA is suspected in a breastfed baby is a structured elimination and reintroduction process, which needs to be done properly to give a reliable answer. A dietitian guides this process to ensure it's nutritionally safe and gives clear results.

For formula-fed babies, the approach is a switch to a specialist formula, specialist formulas are available on prescription, and a dietitian helps identify the right one and guides the transition. Your GP prescribes the formula, and a dietitian helps with the transition, monitoring, and planning the reintroduction ladder when the time comes.

A dietetic assessment matters here for several reasons. Maternal exclusion diets need to keep your own nutrition adequate, particularly calcium and iodine. The reintroduction protocol, often called the milk ladder, needs to be properly timed and structured. And there's an important conversation about when to reintroduce, because most children outgrow CMPA by age 3 to 5.

Current evidence strongly supports early introduction of allergenic foods from around 6 months, with regular ongoing exposure. The landmark LEAP and EAT trials demonstrated that early, sustained introduction of peanut and other allergens can reduce the risk of developing allergies. Delaying introduction beyond 12 months does not protect against allergy and may actually increase risk.

The practical approach to safe allergen introduction — which foods, in what form, how often — depends on your baby's individual risk profile and is something a consultation covers in detail. Sustained exposure is part of how oral tolerance develops.

This is an area where there is a lot of confusion. Skin prick tests and specific IgE blood tests are genuinely useful for diagnosing immediate (IgE-mediated) allergies. If your baby had an immediate reaction to a food, these tests can help confirm the allergy and guide management.

However, these tests are not useful for diagnosing delayed, non-IgE-mediated allergies, which is how most CMPA and many other food allergies present in infants. Delayed allergies are diagnosed through a structured exclusion diet followed by a supervised reintroduction. There's no blood test that reliably identifies them.

Be particularly cautious of commercial 'food intolerance tests' such as IgG testing, hair analysis, or kinesiology. These have no good evidence base, are not recommended by the British Dietetic Association, and frequently produce false positive results that lead to unnecessary dietary restriction in babies. A proper allergy and dietary assessment is what you actually need. This is exactly what I do in a consultation.

Once a food allergy is confirmed, the practical management involves complete avoidance of the trigger food, reading labels carefully, ensuring nutritional adequacy despite the restriction, and planning for eventual reintroduction. For CMPA specifically, a structured reintroduction protocol exists for gradually reintroducing dairy. The timing and pace depend on the severity of the original reaction, and a dietitian guides the process.

Families often need support with the day-to-day reality of managing an exclusion diet for a baby. Making sure the diet is nutritionally complete, knowing what to look for on labels, managing weaning with a restricted diet, and dealing with the anxiety that naturally comes with food allergy in a young child. A dietetic review can help with all of these and usually leaves parents feeling more confident and in control.