Nutrition is one of the most easily modifiable environmental factors during early life that may play a role in allergic disease prevention. This chapter summarizes current evidence on both maternal and infant nutrition as important considerations to target as strategies, in order to improve immune development outcomes and reduce the burden of allergic disease in many communities. Research in this field is not straightforward and inconsistencies in our human evidence base to date are likely to reflect the inherent complexity of each individual's diet, difficulty in accurately measuring it, and interplay with many other environmental and lifestyle factors. However, there remains enormous scope for addressing the role of many dietary factors as potential allergy prevention strategies through well-designed randomized controlled trials. Future research should also include studies to investigate the role of individual genetic polymorphisms and their influence on the interplay between nutritional status in early life and allergic disease outcomes.