Prolonged breastfeeding does not protect against eczema, global study shows

Breastfeeding is still considered by many to be an important strategy to prevent the development of eczema and other allergic diseases, and most health ministries in Europe advocate four months of exclusive breastfeeding to aid allergy prevention. The World Health Organization (WHO), UK Department of Health, and US Department of Health and Human Services all recommend exclusive breastfeeding up to six months of age, but until now little has been known about the effect of breastfeeding on eczema in developing countries.

The researchers, based at King's College London, The University of Nottingham and the University of Ulm, Germany, looked at data from 51,119 children aged 8 to 12, in 21 countries across Europe, Latin America, Africa and Asia. The study formed Phase Two of The International Study of Asthma and Allergies in Childhood (ISAAC), the largest epidemiological research project ever undertaken. Information on eczema, breastfeeding and time of weaning was gathered by parental questionnaire. Children also underwent a skin examination for eczema and skin prick testing to environmental allergens, including house dust mite.

The researchers found no evidence for a protective effect of breastfeeding and delayed weaning on eczema risk in both developed and developing countries, in keeping with other more recent studies, suggesting that the current breastfeeding guidelines with regard to eczema need to reviewed.

The authors also point out that there is mounting evidence to suggest that the early introduction of potentially allergenic food proteins, such as peanut, could increase tolerance to these foods, rather than causing allergy, although this remains to be confirmed in intervention studies.

Dr Carsten Flohr, one of the researchers based at King's College London, said: 'Although there was a small protective effect of breastfeeding per se on severe eczema in affluent countries, we found no evidence that exclusive breastfeeding for four months or longer protects against eczema in either developed or developing nations. We feel that the UK breastfeeding guidelines with regard to eczema should therefore be reviewed. Further studies are now required to explore how and when solids should be introduced alongside breastfeeding to aid protection against eczema and other allergic diseases.'

Dr Flohr is keen to emphasise that other benefits of breastfeeding on infant health, unrelated to eczema, are not being disputed. He explained: 'It is widely accepted that breast milk is the most important and appropriate nutrition in early life. Especially in the context of developing countries it is also important to keep in mind that exclusive breastfeeding reduces the risk of gastrointestinal infections compared to mixed or bottle feeding. Our study does not change this notion.'

Nina Goad of the British Association of Dermatologists said: 'The size of this study means that its findings are very significant, although the authors recognise that further studies are required. Following these further studies we may need to review the UK's advice on how long mothers should breastfeed exclusively for, and at what age we should be weaning our infants, in relation to eczema prevention.

'This study isn't about the benefits of infant formula milk versus breast milk, nor is it questioning other benefits of breast feeding, but it is about whether breastfeeding exclusively for prolonged periods and weaning after six months, as opposed to after four months, has any impact on eczema risk.'

Professor Hywel Williams from the University of Nottingham added: 'There is no doubt that breast is best in terms of prevention of infections and parental bonding, but mothers who cannot breastfeed should not feel guilty if their child develops eczema. The evidence that prolonged and exclusive breastfeeding protects against eczema is not convincing.'

The study, entitled "Lack of evidence for a protective effect of prolonged breastfeeding on childhood eczema: Lessons from the International Study of Asthma and Allergies in Childhood (ISAAC) Phase Two" is published in the British Journal of Dermatology.