Overall, it is known that there are relationships between maternal diet and food allergy in the infant/child, but the details about which foods are protective or promote allergy development are unclear.
“There is still much room for improvement in our knowledge related to the maternal diet in pregnancy and breast feeding, as well as infant feeding and allergy prevention,” said Carina Venter, PhD, RD from Children’s Hospital of Colorado and University of Colorado Anschutz Medical Campus, in a presentation.
Dr. Venter reviewed two central questions relating to food allergy prevention—how does the maternal diet during pregnancy relate to allergy prevention in infants, and how does breast feeding and the maternal diet during breast feeding affect allergy outcomes?
For the first question, Venter summarized observational studies on food patterns in pregnant women and allergy prevention. Only eight studies looked at food patterns in pregnancy, but no studies looked at food allergy as an outcome. No evidence supporting any one type of diet in preventing food allergy in infants was found. Another set of studies looked at fruit and vegetable consumption and showing conflicting results as to which fruits and vegetables were helpful in preventing or causing allergy (atopic dermatitis, asthma/wheeze, sensitization, and rhino conjunctivitis). None of the studies showed any impact in either direction on food allergy.
Two randomized controlled trials looked at vitamin D and multivitamins, but neither reported an effect on food allergy outcomes in infants. A meta-analysis looking at the role of omega-3 fatty acid supplementation found that intake during pregnancy may help reduce egg allergy.
“None of the studies in the meta-analysis were done in only during pregnancy, so there is the potential for different timing of supplementation,” Venter cautioned. One study on the use of probiotics, specifically L. rhamnosus, showed a protective effect against developing atopic dermatitis, although no information on intake during pregnancy was provided.
To the second question, Dr. Venter noted that most mothers will choose to breast feed regardless of the food allergy outcome. Current data can be controversial, and the mechanisms of breast feeding protecting against allergic disease are unclear. Breast milk composition adds to the complexity of understanding the mechanisms and relationship between breast milk and infant food allergy because the composition varies substantially between mothers. Many factors present in breast milk have the potential to play a role in allergic disease, including oligosaccharides, long chain fatty acids, cytokines, hormones, antioxidants, immune-regulating substances, and immunoglobulin A.
Not all mothers will excrete allergen proteins into the breast milk, which represents another complicating factor. In one study, 23 mothers consumed 50 grams of dry roasted peanuts. The peanut protein could be detected in breast milk as early as 1 hour after consumption, but only in about 50% (11/23) of mothers was peanut protein excreted (and at low levels). Comparatively, for the egg allergen, 75% of mothers who eat egg will excrete ovalbumin proteins into their breast milk. Two studies that performed intervention trials trying to build on the relationship of allergen consumption and the effect on food allergy in the infants, which generated conflicting results.
Venter commented, “This is disappointing, but perhaps we need to wait to have better data to distinguish what is actually going on—additional research is needed to tease out how much overlap there is between diet during pregnancy and breast feeding and food allergy outcomes.”