The impact of maternal diet in pregnancy and lactation on allergy and atopy outcomes in offspring: A systematic review

Allergic disease and atopy create a substantial emotional and financial burden for affected individuals and their families. Significant healthcare costs are also incurred with New Zealand children showing consistently high rates of allergic disease when compared with global statistics. The potential to decrease the incidence of allergic disease and atopy through modification of maternal diet has been the subject of recent attention with the possibility for transgenerational impact being of considerable interest. The objectives of this systematic review were firstly to investigate the relationship between maternal diet in pregnancy and lactation on allergic outcomes in the offspring, and to then relate these findings to the New Zealand context. The following databases were accessed as part of this review: PubMed via helicon (advanced search), ProQuest (MEDLINE) via helicon, CINAHL Complete (EBSCO host via helicon). Limits were “humans”. The key search terms were ‘diet’ or ‘supplements’, ‘pregnancy’ or ‘lactation’, ‘allergy’ or ‘atopy’ or ‘asthma; NOT ‘elimination’ or ‘avoidance’. The studies for inclusion in this review were restricted to studies written in the English language. The final search was undertaken 11/04/17 once data extraction completed and one new study found. Initial search was 14/07/16. Search period 14/04/16-11/04/17. Randomised controlled trials and cohort studies that systematically recorded maternal intake of diet or supplements were included. The health-related outcomes assessed were asthma, wheeze, eczema and allergic rhinitis. Data was extracted for this review using the Cochrane Public Health Group’s template. Risk of bias was assessed using the Cochrane risk of bias assessment tool for the randomised controlled trials and the Newcastle-Ottawa Scale for the cohort studies. Risk of bias was assessed again and presented using the Grade summary of findings tables. Overall, 54 studies were included in this review, collectively involving more than 100,000 children and comprising of 16 randomised controlled trials and 38 cohort studies that were selected based on predetermined inclusion and exclusion criteria. Data on vitamins, oligo-elements, food groups and dietary patterns during pregnancy and lactation were also collected. A meta-analysis was not performed due to the diversity in variables, multiple outcomes assessed, and the variety of measurements implemented within the studies. This work presents a comprehensive summary and review of the identified studies that explored the impact of maternal diet in pregnancy and lactation on allergy and atopy outcomes. Although individual studies demonstrated various associations between maternal diet during pregnancy and lactation to impact on health outcomes for the offspring, overall, this work did not show any consistent findings collectively across the studies reviewed. This was due to the differing methods of measurement of association, intake and outcome assessment used in the reviewed studies which further complicated the ability to compare and contrast the findings of the studies with each other. Each study was assessed both for its individual findings and then collectively according to the variables assessed. The findings of this review lend support for the undertaking of additional trials and studies with more consistent and controlled measurements of interventions and outcomes to better facilitate comparisons between studies. Key findings from the reviewed studies, which included only one New Zealand based study, were related to the New Zealand context. Additional New Zealand based information and related works highlighted a need for personally tailored maternal nutrition information to be delivered consistently by all health professionals interacting with pregnant women. Key words: diet, supplements, pregnancy, lactation, allergy, atopy, asthma