The prevalence of allergic diseases such as allergic rhinitis, asthma, food allergy, and atopic dermatitis has increased dramatically during the last decades, which is associated with altered environmental exposures and lifestyle practices. The purpose of this review was to highlight the potential role for dietary fatty acids, in the prevention and management of these disorders. In addition to their nutritive value, fatty acids have important immunoregulatory effects. Fatty acid-associated biological mechanisms, human epidemiology, and intervention studies are summarized in this review.The influence of genetics and the microbiome on fatty acid metabolism is also discussed. Despite critical gaps in our current knowledge, it is increasingly apparent that dietary intake of fatty acids may influence the development of inflammatory and tolerogenic immune responses. However, the lack of standardized formats (ie, food versus supplement) and standardized doses, and frequently a lack of prestudy serum fatty acid level assessments in clinical studies significantly limit our ability to compare allergy outcomes across studies and to provide clear recommendations at this time.Future studies must address these limitations and individualized medical approaches should consider the inclusion of specific dietary factors for the prevention and management of asthma, food allergy, and atopic dermatitis. K E Y W O R D Sasthma, atopic dermatitis, food allergy, nutrition, rhinitis

To fully understand the role of diet diversity on allergy outcomes and to set standards for conducting research in this field, the European Academy of Allergy and Clinical Immunology Task Force on Diet and Immunomodulation has systematically explored the association between diet diversity and allergy outcomes. In addition, a detailed narrative review of information on diet quality and diet patterns as they pertain to allergic outcomes is presented. Overall, we recommend that infants of any risk category for allergic disease should have a diverse diet, given no evidence of harm and some potential association of benefit in the prevention of particular allergic outcomes. In order to harmonize methods for future data collection and reporting, the task force members propose relevant definitions and important factors for consideration, when measuring diet diversity in the context of allergy. Consensus was achieved on practice points through the Delphi method. It is hoped that the definitions and considerations described herein will also enable better comparison of future studies and improve mechanistic studies and pathway analysis to understand how diet diversity modulates allergic outcomes.

Rationale: Allergic diseases are an increasing public health concern, and early life environment is critical to immune development. Maternal diet during pregnancy has been linked to offspring allergy risk. In turn, maternal diet is a potentially modifiable factor, which could be targeted as an allergy prevention strategy. In this systematic review, we focused on non-allergen-specific modifying factors of the maternal diet in pregnancy on allergy outcomes in their offspring. Methods: We undertook a systematic review of studies investigating the association between maternal diet during pregnancy and allergic outcomes (asthma/wheeze, hay fever/allergic rhinitis/seasonal allergies, eczema/atopic dermatitis (AD), food allergies, and allergic sensitization) in offspring. Studies evaluating the effect of food allergen intake were excluded. We searched three bibliographic databases (MEDLINE, EMBASE, and Web of Science) through February 26, 2019. Evidence was critically appraised using modified versions of the Cochrane Collaboration Risk of Bias tool for intervention trials and the National Institute for Clinical Excellence methodological checklist for cohort and case-control studies and meta-analysis performed from RCTs. Results: We identified 95 papers: 17 RCTs and 78 observational (case-control, crosssectional, and cohort) studies. Observational studies varied in design and dietary intakes and often had contradictory findings. Based on our meta-analysis, RCTs showed that vitamin D supplementation (OR: 0.72; 95% CI: 0.56-0.92) is associated with a reduced risk of wheeze/asthma. A positive trend for omega-3 fatty acids was observed for asthma/wheeze, but this did not reach statistical significance (OR: 0.70; 95% CI: 0.45-1.08). Omega-3 supplementation was also associated with a non-significant decreased risk of allergic rhinitis (OR: 0.76; 95% CI: 0.56-1.04). Neither vitamin D nor omega-3 fatty acids were associated with an altered risk of AD or food allergy. Conclusions: Prenatal supplementation with vitamin D may have beneficial effects for prevention of asthma. Additional nutritional factors seem to be required for modulating the risk of skin and gastrointestinal outcomes. We found no consistent evidence regarding other dietary factors, perhaps due to differences in study design and host features that were not considered. While confirmatory studies are required, there is also a need for performing RCTs beyond single nutrients/foods.

Background: Diet Diversity (DD) during infancy may prevent food allergies (FA), possibly by exposing the gastrointestinal microbiota to diverse foods and nutrients.Objective: To investigate the association between four different measures of DD during infancy and development of FA over the first decade of life.Methods: A birth cohort born between 2001/2002 were followed prospectively, providing information on socio-demographic, environmental and dietary exposures. Information on age of introduction of a range of foods and food allergens were collected during infancy. Children were assessed for food allergy at 1, 2, 3 and 10 years. DD was defined using four measures in the first year of life: the World Health Organisation (WHO) definition of minimum DD at 6 months, as food diversity (FD) and fruit and vegetable diversity (FVD) at 3, 6 and 9 months, and as food allergen diversity (FAD) at 3, 6, 9, 12 months.Results: 969 pregnant women were recruited at 12 weeks gestation. 900, 858, 891 and 827 offspring were assessed at 1, 2, 3 and 10 years. Univariate analysis showed that WHO DD (p=0.0047), FD (p=0.0009), FAD (p=0.0048) and FVD (p=0.0174) at 6 months and FD (p=0.0392), FAD (p=0.0233), and FVD (0.0163) at 9 months significantly reduced the odds of FA over the first decade of life. DD measures at 3 months were not associated with FA but only 33% of the cohort had solid foods introduced by this age. ConclusionIncreased infant DD, as measured by four different methods, decreased the likelihood of developing FA. Highlights box:1. What is already known about this topic? Diet Diversity (DD) during infancy may be beneficial for future health.2. What does this article add to our knowledge? Increased DD measured using four different methods from 6 months onwards, in the first year of life, may decrease the likelihood of FA over the first decade. However, DD at 3 months showed no significant effect on food allergy outcomes. How does this study impact current management guidelines?These findings support the recommendation that early oral intake of a variety of foods and food allergens, once the infant is developmentally ready, will reduce incidence of food allergy in the first 10 years of life.