Several attempts are made towards decreasing or alleviating the allergenicity of certain foods as discussed below:
1. Cow’s Milk Allergy:
The first adverse reactions to cow’s milk were already described 2000 years ago. However, the analysis of cow’s milk allergens started only 50 years ago. Administration of probiotics in addition to elimination diet and base treatment to infants improved gastrointestinal manifestations of cow’s milk allergy.
Exclusive breastfeeding may help to prevent allergic disease among infants by decreasing exposure to exogenous antigens, protecting against infections, promoting gastrointestinal mucosal maturation and the development of gut microbiota, and conferring immuno-modulatory and anti-inflammatory benefits. Promotion of breastfeeding, the use of hydrolysed formula for lactose intolerant infants in the first 6 months of life and introduction of solid foods between 4 and 6 months are recommended.
2. Egg White Allergy:
Egg allergy has been shown to be the most common food allergy in children with atopic dermatitis. Hen eggs are one of the most frequent causes for adverse reactions affecting approximately 1.6 per cent of children.
Heated foods often present low allergenicity, and have recently been used in specific oral immunotherapy for food allergies. Since, the intact proteins in raw egg are responsible for their allergenicity, denaturation of the same could be a preventive strategy. The effectiveness of heat treatment at various levels and duration on the allegenicity of egg white has been tested by several scientists.
The ovalbumin (OVA, a major allergen) in egg white heated at 100°C for 5 min lost allergenicity, but demonstrated higher digestive stability and slower absorption in intestine, without causing inflammation while untreated egg white presented intestinal inflammation. The loss of potential allergenicity of OVA was at the expense of increased IgG reactivity. Glycation of OVA on heating also significantly reduced its potential allergenicity.
Whereas baking or boiling of egg white for 30 minutes rather than 10 minutes resulted in a significant reduction in allergenicity as evident from the decreased intensity of the protein band at 45 kD (corresponding to ovalbumin). Thus the duration rather than the temperature in heat treatment was shown to influence the composition and reduce allergenicity of egg white proteins.
Many children with IgE-mediated allergy to egg can tolerate egg in baked foods. Out of 236 egg-allergic children who had been strictly avoiding egg in their diet and put on open food challenge to baked egg, 64 per cent passed and successfully incorporated baked egg into their diet. Only 36 per cent reacted to this challenge. However, Turner et al (2013) therefore recommended that open food challenge to baked egg should take place under medical supervision.
On the other hand observational studies suggest that early regular ingestion of allergenic foods might reduce the risk of food allergy. Palmer et al. (2013) confirmed that induction of immune tolerance pathways and reduction in egg allergy incidence can be achieved by early regular oral egg exposure in infants with eczema but cautioned that these high-risk infants when first exposed to egg may have sensitization already by 4 months of age.
3. Peanut Allergy:
Among food allergies, peanut allergy is frequently associated with severe anaphylactic reactions. The only preventive measure for peanut allergy is strict avoidance of the incriminating food. The use of the anti-IgE therapy in conjunction with other immunotherapy has been recommended by Pons et al. (2005).
Recently, it was reported that Transforming growth factor beta (TGF- β) induced in the gut by VSL#3 (A probiotic medical food) supplementation, is capable of reducing the Th2 inflammation associated with food anaphylaxis in a mouse model of peanut sensitization. TGF-β acts through the induction/maintenance of regulatory T cells expressing FOXP3 and/or latency-associated peptide.
Despite that during childhood natural tolerance development is frequent, some children with cow’s milk or hen’s egg allergy and the majority of children with peanut allergy remain allergic until adulthood, limiting not only the diet of patients but also their quality of life.
Certain foods, food hydrolysates, phytochemicals and probiotic organisms have been identified with anti-allergic properties, emphasizing the food based approach as a remedial measure to food allergies.