The prevalence of allergic diseases increased during past decades, but has more recently plateaued. Dietary changes, especially an altered fatty acid consumption of diet, may be contributing to this phenomenon. However, the results of studies examining this hypothesis remain inconsistent. This review extends the work previously conducted by Sausenthaler et al. which summarized the literature published up to 2005. The current article includes findings from observational studies investigating the association between dietary fat intake and allergic diseases and allergic sensitization published after 2005. In general, the results of these recently published studies are inconclusive, partly conflicting, and do not convincingly support the notion that dietary intake is related to the onset of allergic diseases and allergic sensitization. However, the association between fish consumption and allergic diseases appears most consistent. We hypothesize that improvement in dietary intake assessment in combination with the measurement of fatty acid composition in tissues, while considering the genetic co-effects of the FADS genes, may lead to a better understanding of the underlying mechanisms regulating the associations between food intake and allergies. Dietary recommendations could thus be improved, leading to a better prevention of allergic diseases. Future studies should aim to identify the role of dietary intake and genetic determinants of fatty acid metabolism on the development of allergic diseases.