Why We Develop Food Allergies

Coached by breast milk and good bacteria, the immune system strives to learn the difference between food and pathogens before the first morsel crosses our lips

Per Brandtzaeg

Last Course

Zooming out from all this complexity, the phenomenon of oral tolerance rests on a few primary processes: SIgA antibodies, the barrier function of the gut epithelium, the timing and dose of inoculation with commensal bacteria, and family history. These variables are interdependent, and no single factor predominates in maintaining mucosal homeostasis. There is no single cause of food allergy.

From an evolutionary perspective, intolerance to certain dietary antigens is not too surprising. It has not been long since human beings began growing and preparing their food rather than hunting and gathering it. And evolution is slow when the undesirable phenotype is so seldom deadly.

We must also keep in mind that the current epidemic of allergy in industrialized countries is a small price to pay for the remarkable reduction of infant mortality provided by the elimination of pathogens through improved hygiene. Having too few microbes in our immediate environment seems to be problematic, but having many pathogens is far, far worse. Nevertheless, the pace of research raises hope that future therapies will compensate for the missing good microbes needed to develop homeostasis of mucosal immunity.

Bibliography

Benn, C. S., J. Wohlfahrt, P. Aaby, T. Westergaard, E. Benfeldt, K. F. Michaelsen, B. Björksten and M. Melbye. 2004. Breastfeeding and risk of atopic dermatitis, by parental history of allergy, during the first 18 months of life. American Journal of Epidemiology 160:217-223.
Bischoff, S., and S. E. Crowe. 2005. Gastrointestinal food allergy: New insights into pathophysiology and clinical perspectives. Gastroenterology 128:1089-1113.
Brandtzaeg, P. 2002. Current understanding of gastrointestinal immunoregulation and its relation to food allergy. Annals of the New York Academy of Sciences 964:13-45.
Brandtzaeg, P. 2002. Role of local immunity and breast-feeding in mucosal homeostasis and defence against infections. In Nutrition and Immune Function, eds P. C. Calder, C. J. Field and H. S. Gill, 273-320. No. 1 of Frontiers in Nutritional Science. Oxford, UK: CABI Publishing.
Brandtzaeg, P. 2006.The changing immunological paradigm in coeliac disease. Immunology Letters 105:127-139.
Eggesbø, M., G. Botten, H. Stigum, P. Nafstad and P. Magnus. 2003. Is delivery by cesarean section a risk factor for food allergy? Journal of Allergy and Clinical Immunology 112:420-426.
Guarner, F., R. Bourdet-Sicard, P. Brandtzaeg, H. S. Gill, P. McGuirk, W. van Eden, J. Versalovic, J. V. Weinstock and G. A. W. Rook. 2006. Mechanisms of disease: The hygiene hypothesis revisited. Nature Clinical Practice Gastroenterology & Hepatology 3:275-284.
Haddeland, U., P. Brandtzaeg and B. Nakstad. In press. Maternal allergy influences the proliferation of neonatal T cells expressing CCR4, CXCR5 or CD103. Clinical & Exp er imental Allergy.
Haddeland, U., A. B. Karstensen, L. Farkas, K. L. Bø, J. Pirhonen, M. Karlsson, W. Kvåvik, P. Brandtzaeg and B. Nakstad. 2005. Putative regulatory T cells are impaired in cord blood from neonates with hereditary allergy risk. Pediatric Allergy and Immunology 16:104-112.
Holt, P. G., and C. A. Jones. 2000. The development of the immune system during pregnancy and early life. Allergy 55:688-697.
Ivarsson, A., O. Hernell, H. Stenlund and L. A. Persson. 2002. Breast-feeding protects against celiac disease. American Journal of Clinical Nutrition 75:914-921.
Karlsson, M., M. R. Karlsson, J. Rugtveit and P. Brandtzaeg. 2004. Allergen-responsive CD4⁺CD25⁺ regulatory T cells in children who have outgrown cow's milk allergy. Journal of Experimental Medicine199:1679-1688.
Rakoff-Nahoum, S., J. Paglino, F. Eslami-Varzaneh, S. Edberg and R. Medzhitov. 2004. Recognition of commensal microflora by toll-like receptors is required for intestinal homeostasis. Cell 118:229-241.
Rautava, S., O. Ruuskanen, A. Ouwehand, S. Salminen and E. Isolauri. 2004. The hygiene hypothesis of atopic disease—an extended version. Journal of Pediatric Gastroenterology and Nutrition 38:378-388.
Sicherer, S. H., A. Muñoz-Furlong and H. A. Sampson. 2003. Prevalence of peanut and tree nut allergy in the United States determined by means of a random digit dial telephone survey: A 5-year follow-up study. Journal of Allergy and Clinical Immunology 112:1203-1207.
Sicherer, S. H., and H. A. Sampson. 2006. 9. Food allergy. Journal of Allergy and Clinical Immunology 117(2 Supplemental Mini-Primer): S470-475.
van Odijk, J., I. Kull, M. P. Borres, P. Brandtzaeg, U. Edberg, L. Å. Hanson, A. Høst, M. Kuitunen, S. F. Olsen, S. Skerfving, J. Sundell and S. Wille. 2003. Breastfeeding and allergic disease: A multidisciplinary review of the literature (1966-2001) on the mode of early feeding in infancy and its impact on later atopic manifestations. Allergy 58:833-843.