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Asthma and Diet in Early Childhood

A guide for health professionals
Current suggestions   

Primary prevention, diet and asthma   
Quality of the evidence   

Summary of current evidence 
Identifying high-risk infants

Pregnancy    

Breastfeeding  

Breastfeeding and asthma  
Maternal diet during lactation

Formula feeding     

Infant feeding after six months of age 

Polyunsaturated fatty acids 
Probiotics  

Combining interventions 
Levels of evidence 
References    

Technical writers

Disclaimer

Further information
Content created MAR 2005
Content updated MAR 2005

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NextBackProbiotics

Improved hygiene conditions and the consequent reduction in early-life exposure to microbes have been associated with a heightened risk of allergic diseases. The initial compositional development of gut microbiota may be a key determinant in the development of both immune responder phenotype and the normal gut barrier functions.27-28

Probiotics are viable bacteria that colonise the intestine and modify the intestinal microflora and their metabolic activities, with a presumed beneficial effect for the host.31 Lactic acid bacteria, such as lactobacillus, occur naturally in the intestine and have been used in many studies in the treatment of childhood infections.30-31 The use of probiotics in the prevention of atopic diseases is also under exploration.

Probiotic supplementation

In a prospective randomised placebo-controlled study,27, 32 Lactobacillus GG given to pregnant women during gestation and to their infant for the first 6 months of life was associated with reduced prevalence of atopic eczema up to four years of age. The effect on development of asthma is yet to be shown.

Pre and postnatal supplementation

Mothers in the study were given 1x1010 colony-forming units of Lactobacillus GG daily for 2-4 weeks before expected delivery. After delivery, breastfeeding mothers continued to take the capsules and formula-fed infants were given the contents of the capsule mixed with water by spoon. Both modes of administration resulted in similar amounts of Lactobacillus GG in infant faeces. Capsules were taken postnatally for 6 months.

 As part of this study, the effect of probiotic supplementation on the composition of breast milk was examined.33 The immunoprotective potential of breast milk was found to increase, as assessed by the amount of anti-inflammatory transforming growth factor _2 (TGF-2) in the milk. The infants most likely to benefit from the intervention were those with an elevated cord blood IgE concentration.

Probiotic intervention has not been shown to cause any harm and almost certainly results in a more friendly gut flora, which may have other beneficial effects on health apart from reducing rates of atopic disease.4

Combining interventions

Four cohort studies currently in progress have combined a dietary intervention with other allergen avoidance measures.50

The Canadian Primary Prevention Study combined measures to reduce exposure to inhalant and food allergens.51 The dietary intervention included:

  • antigen avoidance during pregnancy and lactation

  • breastfeeding for 4-12 months or use of partially hydrolysed formula up to 12 months

  • delayed introduction of cow’s milk, seafood and peanuts until 12 months.

The program resulted in a significant reduction in the risk of asthma at the age of 12 months in high-risk infants.

The Isle of Wight Study used a combination of interventions targeting dust mite and food allergens up to 9 months of age.52 Dietary interventions included allergen avoidance during lactation and delayed introduction of potential allergens until after 9 months of age.

The combined intervention has resulted in statistically significant reductions in wheeze with bronchial hyper-responsiveness in children aged 8 years.

In the Study on the Prevention of Allergy in Children in Europe house dust mite avoidance was combined with breastfeeding or the use of hypoallergenic formulas.53 Introduction of potentially allergenic foods was delayed.

Results reported at 1 year showed a reduction in sensitisation to mites and also in atopy. There was no difference in the proportion of children who had ever wheezed.

In the CAPS, the dietary intervention was not designed to reduce exposure to potentially allergenic foods but to increase dietary omega-3 fatty acids (see previous page).

As discussed, this study has shown reduced levels of wheeze in the first 3 years of life.34

Of these studies, only the CAPS is of factorial design and allows investigators to determine which of the interventions is responsible for the difference in clinical outcomes. Further follow-up of these studies may provide a greater understanding of the aetiology of asthma.

The results of these trials to date suggest that a combination of interventions may be more effective in primary prevention than single interventions.

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