The prevalence of reported cases of asthma and allergic disease has seen a marked increase throughout the world since the 1960s, particularly in more developed, westernised countries. A key focus of research in this area has been the possible adverse effects of foetal and infant exposure to food allergens. There is some evidence that foetal and infant exposure to a range of allergens via the mother and her breast milk is important in the development of normal immune tolerance. Current advice is that pregnant and breastfeeding women do not need to avoid potential food allergens unless they are allergic themselves, or are advised to modify their diet by a health professional. Delaying the introduction of common food allergies beyond 6 months is unlikely to reduce the likelihood of food allergy and allergic disease. The findings of current ongoing trials investigating the potential benefits of early introduction on allergenic foods into the diet of children-as well as the comprehensive review of complementary and young-child feeding advice currently being conducted by the Scientific Advisory Committee on Nutrition-will help inform guidance in this area.