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IgE-mediated food allergies in infants are a significant health concern, with peanut allergy being of particular interest due to its prevalence and severity. Among individuals who produce peanut-specific IgE some experience no adverse reaction on peanut consumption. This asymptomatic phenotype is known as sensitized tolerance. To elucidate the immune environment of peanut sensitized tolerant and clinically allergic one-year-olds, high-dimensional mass cytometry was conducted as part of the HealthNuts study. The resulting data includes peripheral blood mononuclear cells from 36 participants encompassing non-allergic, peanut sensitized with tolerance, and clinically peanut allergic infants. The raw mass cytometry data is described here and freely available for reuse through the Immunology Database and Analysis Portal (ImmPort). Additional allergy information and serum vitamin D levels of the participants were measured and are also included in the data upload. These high-dimensional mass cytometry data, when combined with clinical information, offer a broad immune profile of peanut allergic and sensitized tolerant infants.

Background The home environment is the most important location in young children’s lives, yet few studies have examined the relationship between the outdoor home environment and child physical activity levels, and even fewer have used objectively measured exposures and outcomes. This study examined relationships between objectively assessed home yard size and greenness, and child physical activity and outdoor play. Methods Data were drawn from the HealthNuts study, a longitudinal study of 5276 children in Melbourne, Australia. We used cross-sectional data from a sample at Wave 3 (2013–2016) when participants were aged 6 years (n = 1648). A sub-sample of 391 children had valid accelerometer data collected from Tri-axial GENEActive accelerometers worn on their non-dominant wrist for 8 consecutive days. Yard area and greenness were calculated using geographic information systems. Objective outcome measures were minutes/day in sedentary, light, and moderate-vigorous physical activity (weekday and weekend separately). Parent-reported outcome measures were minutes/day playing outdoors (weekend and weekday combined). Multi-level regression models (adjusted for child’s sex, mother’s age at the birth of child, neighbourhood socioeconomic index, maternal education, and maternal ethnicity) estimated effects of yard size and greenness on physical activity. Results Data were available on outdoor play for 1648 children and usable accelerometer data for 391. Associations between yard size/greenness and components of physical activity were minimal. For example, during weekdays, yard size was not associated with daily minutes in sedentary behaviour (β: 2.4, 95% CI: − 6.2, 11.0), light physical activity (β: 1.4, 95% CI: − 5.7, 8.5) or MVPA (β: -2.4, 95% CI: − 6.5, 1.7), with similar patterns at weekends. There was no relationship between median annual yard greenness and physical activity or play. Conclusion In our study of young children residing in higher socio-economic areas of Melbourne yard characteristics did not appear to have a major impact on children’s physical activity. Larger studies with greater variation in yard characteristics and identification of activity location are needed to better understand the importance of home outdoor spaces and guide sustainable city planning.

In mice, the maternal microbiome influences fetal immune development and postnatal allergic outcomes. Westernized populations have high rates of allergic disease and low rates of gastrointestinal carriage of Prevotella, a commensal bacterial genus that produces short chain fatty acids and endotoxins, each of which may promote the development of fetal immune tolerance. In this study, we use a prebirth cohort (n = 1064 mothers) to conduct a nested case-cohort study comparing 58 mothers of babies with clinically proven food IgE mediated food allergy with 258 randomly selected mothers. Analysis of the V4 region of the 16S rRNA gene in fecal samples shows maternal carriage of Prevotella copri during pregnancy strongly predicts the absence of food allergy in the offspring. This association was confirmed using targeted qPCR and was independent of infant carriage of P. copri. Larger household size, which is a well-established protective factor for allergic disease, strongly predicts maternal carriage of P. copri., Incidence of food allergy in westernized populations is associated with low abundance of Prevotella. Here, the authors analyse the microbiome of a mother-infant prebirth cohort and find that maternal carriage, but not infant carriage, of P. copri during pregnancy predicts the absence of food allergy in the offspring.

The past few years have seen an exponential increase in publications on the topic of IgE-mediated food allergy. Recent publications have greatly advanced our understanding of the global prevalence of food allergy, and have revealed new insights into risk factors for food allergy. In this article, we will review these recent developments, summarise the current state of knowledge of the epidemiology of IgE-mediated food allergy, and outline areas of ongoing research where gaps in evidence remain. Recent publications reveal substantial differences in food allergy prevalence between countries. Data show that the incidence of food-induced anaphylaxis in developed countries continues to rise, particularly in children, although it remains unclear to what extent this is due to an increase in food allergy prevalence, or an increase in severe reactions among allergic individuals, or both. There has been considerable progress in understanding risk factors for food allergy. In particular, there is now good evidence that delayed introduction of peanut increases the risk of developing peanut allergy in infants with pre-existing risk factors for peanut allergy. A shift towards earlier introduction of peanut in these infants, now starting to be recommended in allergy prevention guidelines, may help to prevent peanut allergy in future generations. Recent studies have defined the prevalence of food allergy in different regions of the world. These studies provide strong baseline data to measure the extent to which new food allergy prevention strategies, including recommending timely peanut introduction for high-risk infants, change the prevalence of childhood food allergy.

Precautionary allergen labelling (PAL) has resulted in consumer confusion. Previous research has shown that interpretive labels (using graphics, symbols, or colours) are better understood than the traditional forms of labels. In this study, we aimed to understand if consumers would use interpretive labels (symbol, mobile phone application and a toll-free number) with or without medical advice that was advocated by the food industry rather than the normal PAL. This is relevant information for industry and clinicians as it provides an insight into the food allergic perception regarding PAL.

The identification of food allergy prevention strategies has become an important public health issue given the increase in hospital presentations for food allergic reactions in young children. In particular, there has been an increasing interest in whether the timing of introduction of solids (particularly allergenic solids such as egg and peanuts) plays a role in development of early-onset food allergy. To date, research in the area has primarily been limited to observational birth cohort studies, which have generated data to suggest that delayed introduction of allergenic solids may actually increase rather than decrease the risk of food allergy. However, findings from these studies must be viewed with caution since it is difficult to eliminate the potential for confounding factors to generate spurious associations between infant feeding choices and food allergy risk. The emergence of a number of in progress randomised trials of early introduction of allergenic foods is likely to contribute significantly to understanding of this area as results come to light. This review discusses the current evidence for a role of early introduction of foods in the prevention of food allergy, including emerging results from the first clinical trials, and discusses the implications of these findings for population guidelines and for further research.

The prevalence of precautionary labelling remains high. This prevalence restricts food choices, in some cases perhaps unnecessarily, for food allergic consumers. During processing, cross-contamination does often occur in food products due to the way that modern processing facilities operate; however, zero risk of cross contamination is not a realistic expectation. There is evidence to suggest that threshold levels below which reactions are not provoked in allergic individuals do exist and these have been established in the literature for peanuts. Additional information such as understanding threshold levels will be important to this field of research. The data that will be obtained from future clinical trials will help to underpin action plans for precautionary labelling. This paper will review the current literature that is available regarding: consumer behaviour and attitudes regarding precautionary labelling; risk to the consumer and analytical results of products that bear advisory labelling; the current debate regarding whether a tolerable level of risk can be obtained in food allergy; and finally, the newly introduced Voluntary Incidental Trace Allergen Labelling (VITAL) system operating in Australia.

Tree nuts are one of the most common foods causing acute allergic reactions and nearly all tree nuts have been associated with fatal allergic reactions. Despite their clinical importance, tree nut allergy epidemiology remains understudied and the prevalence of tree nut allergy in different regions of the world has not yet been well characterised. We aimed to systematically review the population prevalence of tree nut allergy in children and adults. We searched three electronic databases (OVID MEDLINE, EMBASE and PubMed) from January 1996 to December 2014. Eligible studies were categorised by age, region and method of assessment of tree nut allergy. Of the 36 studies identified most were in children (n = 24) and from Europe (n = 18), UK (n = 8) or USA (n = 5). Challenge-confirmed IgE-mediated tree nut allergy prevalence was less than 2 % (although only seven studies used this gold standard) while probable tree nut allergy prevalence ranged from 0.05 to 4.9 %. Prevalence estimates that included oral allergy syndrome (OAS) reactions to tree nut were significantly higher (8-11.4 %) and were predominantly from Europe. Prevalence of individual tree nut allergies varied significantly by region with hazelnut the most common tree nut allergy in Europe, walnut and cashew in the USA and Brazil nut, almond and walnut most commonly reported in the UK. Monitoring time trends of tree nut allergy prevalence (both overall and by individual nuts) as well as the prevalence of OAS should be considered given the context of the overall recent rise in IgE-mediated food allergy prevalence in the developed world.