Dr Ashfaq Ahmad, dispensing medical advice in the Leinster Express' new column.
The following recommendations summarise the current evidence related to allergy prevention in children through dietary interventions, keeping in mind that some aspects are currently uncertain due to inadequate study design or paucity of data.
- There is a current lack of evidence that maternal dietary restrictions during pregnancy play a significant role in the prevention of atopic disease in infants. Similarly, antigen avoidance during lactation does not prevent atopic disease, with the possible exception of atopic eczema (although more data are needed to draw a firm conclusion).
- For infants at high risk of developing atopic disease, exclusive breastfeeding for at least four months compared with feeding intact cow milk protein formula appears to decrease the incidence of atopic dermatitis and cow milk allergy in the first two years of life.
- Exclusive breastfeeding for at least three months has been shown to protect against wheezing in early life. However, in infants at risk of developing atopic disease, the current evidence that exclusive breastfeeding protects against allergic asthma occurring beyond six years of age is not convincing.
- In studies of infants at high risk of developing atopic disease who are not breastfed exclusively for four to six months or are formula fed, there is modest evidence that atopic dermatitis may be delayed or prevented by the use of extensively or partially hydrolyzed formula, compared with cow milk formula, in early childhood. Not all formulae have been shown to have the same protective benefit. Extensively hydrolyzed formula may be more effective than partially hydrolyzed in the prevention of atopic disease (partially hydrolyzed formula differs from extensively hydrolyzed formula in that their protein chains can be longer). However, more research is needed to determine whether these benefits extend into late childhood and adolescence. The higher cost of the hydrolyzed formula must also be considered. To date, the use of amino acid–based formula for atopy prevention has not been studied.
- There is no convincing evidence for the use of soy-based infant formula for the purpose of allergy prevention.
- While solid foods should not be introduced before four to six months of age, there is no current convincing evidence that delaying their introduction beyond this period has a significant protective effect on the development of atopic disease (regardless of whether infants are fed cow milk protein formula or human milk). This includes delaying the introduction of foods that are considered to be highly allergic, such as fish, eggs, and foods containing peanut protein.
- For infants after four to six months of age, there are insufficient data to support a protective effect of any dietary intervention for the development of atopic disease.
- Additional studies are needed to document the long-term effect of dietary interventions in infancy to prevent atopic disease, especially in children older than four years and in adults.