Food allergy prevention is of great interest for researchers, since the prevention of food allergy development may lead to reduced prevalence of asthma and allergic rhinitis.
Over the years a lot of strategies have been studied and implemented, such as the maternal avoidance during pregnancy and lactation and delayed introduction of solids into the infant’s diet. Despite the long term effects of these interventions being subsequently shown to be disappointing, these recommendations stayed in place for a number of years. A lot of studies add up to the evidence that the delayed introduction of solids into the infant’s diet did not reduce the risk of developing allergic allergies.
Strategies during pregnancy
There is a lack of evidence that the avoidance of certain food would protect the unborn baby against development of certain allergies. There is a greater risk of maternal nutrient shortages, which would affect the unborn baby’s growth. The emphasis moved from the avoidance of certain foods from the diet to the inclusion of certain food/nutrients into the diet.
- Polyunsaturated fatty acids- increased omega-6 intake is associated with increased inflammatory markers, whereas omega-3 intake inhibits allergic inflammation. Studies are done where the intake of sunflower oil is reduced and the mother’s diet is supplemented with omega-3 rich fish oils. The clinical outcome is still investigated, but it seems positive for improved immunological changes.
- Probiotics- these live micro-organisms plays an important role in the development of mucosal and systemic immune system, specifically the development of oral tolerance. The studies might seem to have conflicting results, but the outcome is influenced by the strain of probiotic used, dosage and time of probiotic use (mother and new born infant). It does seem as if maternal supplementation could have an effect on allergic disease.
- Vitamin D- studies are currently looking at the role of maternal vitamin D exposure and food allergy in their offspring.
- ‘Healthy Diet’- there seems to be a (weak) protective effect of fruit and vegetable intake in the development of asthma and allergy.
Breastfeeding and allergy development
Exclusive breastfeeding is recommended for 6 months, because of its protective effect on gastroenteritis, wheeze, necrotising enterocolitis and vomiting. Breast milk seems to have a protective effect on the development of allergies, only during the months of breast feeding while new foods are introduced. It seems as if there is no long term protective effect of breast milk on the development of food allergies in the toddler after breast feeding has been stopped.
Role of infant formula in allergy prevention
Early exposure to cow’s milk could increase prevalence of cow’s milk allergy. Soy milk formula should not be recommended for the prevention of milk allergy in infants. There is limited evidence that extensively hydrolysed formulas have a protective effect against cow’s milk allergies. The inclusion of pre- and/or probiotics in infant formulas seem to have conflicting results. Therefore, if it is within your budget to use such formula, it could only benefit your infant and would not harm him/her.
Role of infant feeding and allergy development
From 6 months there is no reason to delay the introduction of allergenic foods- e.g. wheat, egg, peanut, cow’s milk products and fish. Delaying weaning beyond 6 months could adversely affect the normal dietary and developmental milestones essential to establish a good varied diet and may increase the risk of allergy development. It would be prudent to introduce allergenic foods one at a time into the diet of high-risk infants.
- Avoid smoking during pregnancy and ensure the baby is not exposed to passive smoking, as this has been associated with development of asthma and allergenic disease in the infant.
- House-dust mite reduction measures have been shown to reduce sensitisation to house-dust mite at 1 year in high-risk infants
- During pregnancy and lactation, the use of anti-reflux medication, paracetomol and non-steroidal anti-inflammatory drugs should be limited.
(J Allergy Society of SA; vol. 25, no. 1, March 2012, p18-23)