Breastfeeding not shown to decrease risk of allergy
Both the DH and the US Food and Drug Administration recommend breastfeeding as a method of reducing the incidence of eczema and atopic disease. Many have regarded the evidence to support this as weak and this paper, a collaboration between researchers at McGill University in Canada and a Belarussian research institute, may cause current guidance to be rewritten.
The research team looked at 17,000 infants of whom nearly 14,000 were followed up at six and a half years. More than half the participants had been born in maternity units where there had been active promotion of breastfeeding; the control group had been born in units where there was standard care. As a consequence the rate and duration of breastfeeding in the experimental group was significantly higher. Both groups were otherwise similar in terms of maternal age, parity, educational attainment and social class.
The authors used a questionnaire to determine if the children had a history of asthma or eczema, and performed skin prick tests for five common allergens on 85% of participants.
The researchers found no decrease in the incidence of asthma, eczema or other allergies in the group with increased breastfeeding compared with the control group. There was even a suggestion that prolonged breastfeeding resulted in an increase in the incidence of positive allergy skin tests, but the team had concerns regarding the reliability of these data.
This study took place in a society very different from the UK, in which the general prevalence of allergy is much lower. It would be comforting to see a similar Western European study, but it is probably impossible logistically to achieve the numbers studied by Kramer and his colleagues.
There are many other reasons why breastfeeding is good for babies and mothers and I am sure that we will continue to remind our patients of these, but it might be prudent to backpedal on the allergy issue.
Kramer MS, Matush L, Vanilovich I et al. Effect of prolonged and exclusive breast feeding on risk of allergy and asthma: cluster randomised trial. BMJ 2007 doi:10.1136/bmj.39304.464016.AEReviewer
Dr Peter Saul
GP, Wrexham and hospital practitioner in paediatrics (asthma and allergy)