For some parents (especially those who suffer from allergies themselves or have children with allergies), trying to prevent an allergy in their children is important. Hypoallergenic formula (which is hydrolysed or predigested) is sometimes recommended for babies who might be prone to allergies, or who already have an allergy.
Can how, or what, a baby is fed really help to prevent allergy?
There is insufficient evidence to say that breastfeeding prevents allergies.
Breastfeeding is not magic. No single factor is likely to prevent anything. Rather, there are multiple factors which might either increase or decrease the risk of various health problems, one of which is likely to be how a baby is fed.
In any case, exclusive breastfeeding for about the first 6 months, and continued breastfeeding, accompanied by solid foods for at least one or two years, are important for the health of both child and mother. You can read more about reasons why breastfeeding is important here.
If a baby isn’t breastfed, are there any types of formula that might help prevent allergy?
Before answering this question, we need to look at what ‘the body of evidence’ means.
The Body Of Evidence For Hypoallergenic Formula
The body of evidence refers to what the breadth of the research indicates, rather than just the results of the latest study (which might or might not be a high quality study). No individual research study stands on its own; it is part of the body of evidence.
While there can be quality individual studies, examining the body of evidence involves systematic reviews and meta-analyses.
Systematic reviews sit at the top of the hierarchy of evidence table, and are considered to provide very high quality evidence. Systematic reviews summarise the research to date, so the conclusions reached are based on the data as a whole (the body of evidence).
A meta-analysis, or statistical analysis, can sometimes be performed on the data combined in a systematic review. This means that the data from several studies are combined and analysed for statistical significance, as if it were one large study.
So, with this information in mind, what does a recent systematic review indicate about formula and allergy prevention?
Hypoallergenic Formulas Don’t Prevent Allergy
The term ‘hydrolysed’ describes proteins that have been broken down into smaller proteins. In theory, if this is done, the immune system might not recognise the protein as something to react to.
A 2006 systematic review, found “limited evidence that prolonged feeding with a hydrolysed formula compared to a cow’s milk formula reduces infant and childhood allergy and infant CMA [cows’ milk allergy].” This led to some guidelines that recommend the use of hydrolysed formulas rather than standard cows’ milk formula to help prevent allergy in babies who are not breastfed and who are at increased risk.
However, a recent systematic review, which reviewed information from 37 trials from 1946-2015, involving 19,000 participants, found “no consistent evidence that partially or extensively hydrolysed formulas reduce risk of allergic or autoimmune outcomes”.
The authors suggested that any guidelines which currently recommend hydrolysed formula to prevent allergy should no longer make such a recommendation.
A very important aspect of this most recent systematic review was that it excluded studies where there had been a high risk of bias, or evidence of conflict of interest (e.g. where manufacturers of hydrolysed formula had supported the study or the investigators).
It’s possible that hypoallergenic formula is recommended for formula fed babies at risk of allergy simply because of a belief that it’s unlikely to do any harm, compared with non-hydrolysed formula. However, there are two problems associated with this:
#1: Promotion Of Any Formula Can Undermine Breastfeeding
Formula, whether hypoallergenic or not, cannot replicate breastmilk. Unfortunately, a mother’s perception of breastfeeding can often be influenced by a health professional’s advocacy for a specific formula. In this way, promotion of any formula can undermine breastfeeding.
#2: Promotion Of Hypoallergenic Formula As Way Of Preventing Allergy Can Affect Further Research
If hypoallergenic formulas continue to be endorsed as a way of preventing allergy in formula fed babies at risk, it could have an impact on further efforts:
- To perform quality research on this topic
- By formula companies to improve their products
More research is needed to find out what can be done to prevent the development of allergies. From an infant feeding perspective, it is important to aim for exclusive breastfeeding for about the first 6 months, and then continued breastfeeding, alongside solid foods, for at least one to two years of age.
Mothers who do not breastfeed need to know they are not doing their babies a disservice by choosing a standard cows’ milk based formula, rather than a hydrolysed formula.