Food allergy (FA) is increasingly reported in Europe, however, the latest prevalence estimates were based on studies published a decade ago. The present work provides the most updated estimates of the prevalence and trends of FA in Europe. Databases were searched for studies published between 2012 and 2021, added to studies published up to 2012. In total, 110 studies were included in this update. Most studies were graded as moderate risk of bias. Pooled lifetime and point prevalence of self‐reported FA were 19.9% (95% CI 16.6–23.3) and 13.1% (95% CI 11.3–14.8), respectively. The point prevalence of sensitization based on specific IgE (slgE) was 16.6% (95% CI 12.3–20.8), skin prick test (SPT) 5.7% (95% CI 3.9–7.4), and positive food challenge 0.8% (95% CI 0.5–0.9). While lifetime prevalence of self‐reported FA and food challenge positivity only slightly changed, the point prevalence of self‐reported FA, sIgE and SPT positivity increased from previous estimates. This may reflect a real increase, increased awareness, increased number of foods assessed, or increased number of studies from countries with less data in the first review. Future studies require rigorous designs and implementation of standardized methodology in diagnosing FA, including use of double‐blinded placebo‐controlled food challenge to minimize potential biases.

In 2014, the European Academy of Allergy and Clinical Immunology published prevalence estimates for food allergy (FA) and food sensitization (FS) to the so‐called eight big food allergens (i.e. cow's milk, egg, wheat, soy, peanut, tree nuts, fish and shellfish) in Europe for studies published between 2000 and 2012. The current work provides 10‐year updated prevalence estimates for these food allergens. A protocol was registered on PROSPERO before starting the research (reference number CRD42021266657). Six databases were searched for studies published 2012–2021, added to studies published up to 2012, resulting in a total of 93 studies. Most studies were graded as at moderate risk of bias. The overall pooled estimates for all age groups of self‐reported lifetime prevalence were as follows: cow's milk (5.7%, 95% confidence interval 4.4–6.9), egg (2.4%, 1.8–3.0), wheat (1.6%, 0.9–2.3), soy (0.5%, 0.3–0.7), peanut (1.5%, 1.0–2.1), tree nuts (0.9%, 0.6–1.2), fish (1.4%, 0.8–2.0) and shellfish (0.4%, 0.3–0.6). The point prevalence of food challenge‐verified allergy were as follows: cow's milk (0.3%, 0.1–0.5), egg (0.8%, 0.5–1.2), wheat (0.1%, 0.01–0.2), soy (0.3%, 0.1–0.4), peanut (0.1%, 0.0–0.2), tree nuts (0.04%, 0.02–0.1), fish (0.02%, 0.0–0.1) and shellfish (0.1%, 0.0–0.2). With some exceptions, the prevalence of allergy to common foods did not substantially change during the last decade; variations by European regions were observed.

IntroductionThe hygiene hypothesis suggests that reduced exposure to microbes might have contributed to the increase in prevalence and incidence of asthma and allergy observed during the second half of the last century. Following this proposal, several studies have investigated the role of sibship size and birth order in the development of asthma and allergic diseases, but the underlying evidence is conflicting. The objective of the present systematic review will be to identify, critically appraise and synthesise previous primary studies investigating the association of sibship size and birth order with the risk of asthma and allergic diseases.Methods and analysisThe following databases will be searched: AMED, CABI, CINAHL, Embase, Google Scholar, OAIster, Open Access Theses and Dissertations, Open Grey, ProQuest Dissertations & Theses Global, PsycINFO, PubMed, SciELO, Scopus, Web of Science and WHO Global Index Medicus. Studies published up until 31 December 2020 will be eligible. There will be no restrictions by language and geographical location. Risk of bias in the included studies will be assessed using the Effective Public Health Practice Project quality assessment tool. The produced evidence will be synthesised narratively, and studies that present comparable numerical data will be included in meta-analyses using random effects model.Ethics and disseminationOnly data from the published literature will be included in this systematic review. Therefore, no ethical approval is required. The final review paper will be published in a peer-reviewed journal.PROSPERO registration numberCRD42020207905.

Background Recent reports indicate that the prevalence of food allergy is increasing, but accurate estimates remain a challenge due to cross‐reactivity and limited use of precise diagnostic methods. Molecular allergy diagnostics, in which sensitization to individual molecular allergens is measured, is emerging as a promising tool for evaluation of sensitization profiles. In this systematic review, we summarized estimates of prevalence of sensitization to molecular food allergens in the general population in Europe. Methods Following a protocol prospectively registered with the International Prospective Register of Systematic Reviews (PROSPERO; reference CRD42021266657), we searched seven databases with no restrictions on publication date or language. Two reviewers independently screened the literature, extracted data, and appraised the risk of bias in the included studies. The findings were synthesized narratively. Results From 4776 de‐duplicated records, five studies, with low to moderate overall risk of bias, were included. Forty‐six molecular allergens from 18 foods were investigated. Overall, the prevalence of sensitization was low, particularly for major allergens, and non‐existent for 10 molecular allergens (0% [95% CI 0–0.8]). The highest prevalence was seen for PR‐10 proteins, such as Cor a 1.04 (13.6% [95% CI 10.9–16.9]). Conclusions Available data, primarily from North‐western Europe, indicate that sensitization to molecular food allergens is overall low. The highest estimates were found for cross‐reactive PR‐10 proteins. There were not enough studies to discern regional differences or perform meta‐analysis, highlighting the need for more population‐representative studies in order to elucidate patterns of sensitization to molecular food allergens in Europe.

Following the “hygiene hypothesis”, a plethora of studies have investigated the role of sibship composition in atopic diseases, but findings are largely conflicting. We undertook the first systematic review to synthesize the global literature linking birth order and sibship size to the risk of allergic rhinitis. Fifteen databases were searched from inception until 20 October 2021. Screening and data extraction were performed in pairs. Comparable numerical data were analyzed using meta-analysis with robust variance estimation (RVE). We included 76 reports based on 66 studies that met our inclusion criteria, encompassing >2 million subjects. Being second- or later-born child was associated with protection against both current (pooled risk ratio [RR] 0.79, 95%CI 0.73-0.86) and ever (RR 0.77, 95%CI 0.68-0.88) allergic rhinitis. Having siblings, regardless of birth order, was associated with a decreased risk of current allergic rhinitis (RR 0.89, 95% CI 0.83-0.95) and allergic rhinoconjunctivitis (RR 0.92, 95%CI 0.86-0.98). These effects were unchanged across age, time period, and geographical regions. Our findings indicate that primarily, a higher birth order, and to a lesser extent the number of siblings, is associated with a lower risk of developing allergic rhinitis.