Prolonged breastfeeding does not protect against eczema, global study shows

The largest worldwide study on the association between breastfeeding, time of weaning and eczema in children has concluded that there is no clear evidence that exclusive breastfeeding for four months or longer protects against childhood eczema. The study, led by scientists at King's College London, and published online in the British Journal of Dermatology (BJD), concludes that children who were exclusively breastfed for four months or longer were as likely to develop eczema as children who were weaned earlier.

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.'

Notes to editors:

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, British Journal of Dermatology, www.brjdermatol.org

China (Hong Kong), France, Germany, Greece, Iceland, Italy, Netherlands, New Zealand, Norway, Spain, UK, Albania, Brazil, China, Ecuador, Georgia, Ghana, India, Latvia, West Bank, Turkey

The International Study of Asthma and Allergies in Childhood, is a unique worldwide epidemiological research programme established in 1991 to investigate asthma, rhinitis and eczema in children due to considerable concern that these conditions were increasing in western and developing countries. ISAAC has become the largest worldwide collaborative research project ever undertaken, involving more than 100 countries and nearly two million children. Its main aim is to develop environmental measures and disease monitoring in order to form the basis for future interventions to reduce the burden of allergic diseases, especially in children in developing countries.

King's College London is one of the top 25 universities in the world (2010 QS international world rankings), The Sunday Times 'University of the Year 2010/11' and the fourth oldest in England. A research-led university based in the heart of London, King's has nearly 23,500 students (of whom more than 9,000 are graduate students) from nearly 140 countries, and some 6,000 employees. King's is in the second phase of a £1 billion redevelopment programme which is transforming its estate.

King's has an outstanding reputation for providing world-class teaching and cutting-edge research. In the 2008 Research Assessment Exercise for British universities, 23 departments were ranked in the top quartile of British universities; over half of our academic staff work in departments that are in the top 10 per cent in the UK in their field and can thus be classed as world leading. The College is in the top seven UK universities for research earnings and has an overall annual income of nearly £450 million.

King's has a particularly distinguished reputation in the humanities, law, the sciences (including a wide range of health areas such as psychiatry, medicine, nursing and dentistry) and social sciences including international affairs. It has played a major role in many of the advances that have shaped modern life, such as the discovery of the structure of DNA and research that led to the development of radio, television, mobile phones and radar. It is the largest centre for the education of healthcare professionals in Europe; no university has more Medical Research Council Centres.

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