Against high profile issues such as obesity and child protection, it is not surprising that childhood atopic dermatitis rarely tops the priority list for midwives and health visitors. More than 60% of children grow out of it by their teens, and thankfully more than 80% of sufferers will only experience the mild form of disease¹. However atopic dermatitis can lead to the onset of other conditions in later childhood such as rhinitis and asthma (the ‘atopic march’)² and place immense emotional distress on the parents³.

About atopic dermatitis

Atopic dermatitis (AD) is a type of eczema, a chronic condition characterised by intense itching, dry skin, inflammation, redness and exudation. This type of eczema is called ‘atopic’ because the subject has atopy - hypersensitivity to common allergens and a predisposition to allergy. AD generally begins in the first year of life, and estimates of prevalence vary. A recent report from NICE (National Institute of Health & Clinical Excellence) cites as many as 15-20% of school children and 2-10% adults with AD1. The causes of AD are not fully understood but include a combination of genetic and environmental factors. The challenge to any parent is to stop the vicious circle of scratching – this damages the skin, increasing inflammation, bleeding and infection, which in turn increases the itch.

Whilst there are a range of skin care and antiinflammatory treatments available, the most attractive option to carers must be a prophylactic one. Given the increased likelihood of an allergy if there is a family history, parents may be keen to try and prevent this from happening to their next child.

Breastfeeding and atopic dermatitis

Breastfeeding confers many benefits to the infant and is undoubtedly the best way to feed the majority of babies. It may also be the simplest strategy to help combat atopic dermatitis. There are conflicting reports in the literature about the preventative effects of breastfeeding and allergy as a whole. However a recent review has concluded that exclusive breastfeeding for at least 4 months, combined with introduction of solid foods after 4 months of age is associated with a reduced risk of food allergy and atopic dermatitis – particularly in at risk infants⁴.

The Ministry of Public Health in the Netherlands has recently attempted to quantify the benefits of breastfeeding to six months through a systematic review of the literature⁵. They investigated a range of conditions and assessed how many cases could be prevented if every baby in Holland was breastfed to at least six months (vs. the current situation of 35% of babies estimated as reaching this target). Table 1 shows the most common conditions reviewed in the report. The contribution of breastfeeding is highly significant against the incidence of these diseases in the Dutch population (the authors report an incidence of about 20% for otitis media, respiratory infections and eczema for example). Notably these conditions suggest a strong effect of breastfeeding on the infant immune system.

Table 1: Quantification of the Health Effects of Breastfeeding in the Netherlands. Shown are the incidences for each scenario that would be prevented if 100% of Dutch infants were breastfed for six months instead months.

Why does breastmilk strengthen the immune system?

As adults we have a complex immune system to protect us from infection and harm. This includes everything from simple barriers to sophisticated immune cells. Babies are born with most of these components in place but their immune system is immature and in need of development. The infant needs to ‘learn’ how to mount an appropriate immune response to potential pathogens, but not to over-react to harmless environmental and food components, as in the case of allergy.

Breastmilk provides the infant with passive immunity during this vulnerable time – as preformed antibodies. In addition, it contains a range of components to support the immune system of the infant such as white blood cells and nucleotides⁶.

However, it is the effect of breastmilk on the infant’s gut flora that is attracting interest in respect of allergy. Breastfed babies typically have more beneficial bacteria (principally bifidobacteria) than bottlefed babies in their colons⁷. This is largely due to the high prebiotic content of breastmilk – oligosaccharides which feed and stimulate the growth of bifidobacteria⁸. These bacteria play an important role in defending the body against infection and are thought to help ‘educate’ the infant’s immune system⁹.

Research has shown that allergic infants typically have lower levels of bifidobacteria than nonallergic infants¹⁰. Thus this might in part explain the role of breastmilk in preventing some allergies.

Prebiotics in infant milk

A special prebiotic mixture of galacto- and fructo-oligosaccharides (GOS and FOS) has been developed for use in some infant milks. Research has shown that when added to infant milk this prebiotic mixture has a strong and consistent effect on the gut flora of infants – increasing levels of bifidobacteria to similar levels as found in breastmilk.^{11, 12} This is coupled with a decrease in potential pathogens such as E.coli and Clostridia¹³.



Prebiotics may help prevent atopic dermatitis
The gut flora results are certainly interesting. However they are limited unless they can be translated into health benefits. At this year’s meeting of the Royal College of Paediatrics and Child Health, Professor Moro from Milan presented the striking results from a new randomised, double-blind placebo controlled trial into prebiotics and atopic dermatitis¹⁴. Two hundred and forty two babies at risk of developing an allergy (i.e. with a family history of atopy) were selected to take part in the trial. All mothers were encouraged to breastfeed their babies, however if the mother decided to bottlefeed, the baby was randomly assigned onto either a formula containing the GOS/FOS mixture or a formula containing a placebo (maltodextrin). The study was blinded such that neither the researchers nor the parents knew which formula each baby was given to avoid introducing bias. At three and six months of age, infants were investigated for AD. As shown in figure 1, the addition of prebiotics to a formula was found to reduce the incidence of atopic dermatitis by over 50%. Two hundred and six children completed the trial, and at six months, 9.8% infants in the GOS/FOS group suffered AD compared with 23.1% in the non-prebiotic formula. This was statistically significant (p=0.014).

In order to verify an effect on the immune system, a subset analysis of the children was conducted to look at immune system markers such as the antibody IgE. An elevated level of IgE is a marker of increased risk of allergy. The group fed prebiotics were found to have a significantly reduced level of IgE compared to the placebo group¹⁵. This is the first clinical study showing an effect of this prebiotic mixture on the immune system and atopic dermatitis. The researchers plan to follow-up the trial group to five years to see if there are any differences in other allergic conditions, such as asthma.

Atopic dermatitis and other allergic conditions are distressing for both babies and parents, therefore any strategies that can reduce the risk of allergy should be researched and supported. Encouraging exclusive breastfeeding and avoiding early weaning before 4 months is certainly nothing new – however this may be particularly beneficial to the child at risk of atopic dermatitis. Infant milk will never be able to match the complex nature of breastmilk, however research suggests that the addition of prebiotics may help support the immune system of the bottlefed infant.

For more information on the immune system and prebiotics visit www.in-practice.co.uk or call one of our experienced advisors in 08457 623 624.

About the author

Dr Natasha Bye is Head of Scientific Affairs for Nutricia UK. The company has spent over 10 years researching the effects of prebiotics in infants. Prebiotics can be found in Cow & Gate and Milupa Aptamil standard milks.

References

1. NICE Technology Appraisal 81. Frequency of applications of topical corticosteroids for atopic eczema. August 2004
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14. Moro et al. Arch Dis Child. 2006 Jul 27; [Epub ahead of print]
15. Moro G. et al. Oral presentation at the 21st International Symposium on Neonatal Intensive Care, Milan, November 2004