The Role of Fermented Foods in Managing Food Allergies in Children and Adults: A Systematic Review

Bahtir Hyseni¹Konstantinos Papadimitriou^2*Aline Issa³Ayşe Nur Tonay⁴Burcu Gündüz Ergün⁵CARMEN MARIA GONZALEZ DOMENECH⁶Elena Arranz⁷Endra Luzha Pula⁸Erenay Erem⁹Enriqueta Garcia-Gutierrez¹⁰Grégory Bouchaud¹¹Hania Szajewska¹²Hatice KALKAN YILDIRIM¹³İbrahim Ender Künili¹⁴Lidia Markiewicz¹⁵Mario Caruana Grech Perry¹⁶Meral Kilic Akyilmaz⁹Mounaim Halim El Jalil¹⁷RYMA MERABTI¹⁸Sandra Mojsova¹⁹Yonca Yuceer²⁰Zehra Gulsunoglu-Konuskan²¹Aslı Akpınar²²Barçın Karakaş-Budak²³Christophe Chassard²⁴Smilja Praćer²⁵Guy Vergères²⁶Simona Lucia Bavaro^27*

• ¹Faculty of Food Technology, University “Isa Boletini” in Mitrovica, Kosovo, Mitrovica, Albania
• ²Department of Food Science & Human Nutrition, Agricultural University of Athens, Athens, Greece
• ³Faculty of Nursing and Health Sciences, Notre Dame University- Louaize, Zouk Mosbeh, PO. Box 72 Zouk Mikael, L:ebanon, Zouk Mikael, Lebanon
• ⁴UCD School of Biosystems and Food Engineering, University College Dublin, Belfield, Dublin, Ireland
• ⁵Department of Molecular Biology and Genetics, Yıldız Technical University, Instanbul, Türkiye
• ⁶Department of Microbiology, School of Medicine, Louis Pasteur Boulevard, University of Malaga, Malaga, Spain
• ⁷Universidad Autónoma de Madrid (CEI UAM+CSIC) and Institute of Food Science Research (CIAL, CSIC-UAM), Madrid, Spain
• ⁸Food Hygiene and Technology Department, Faculty of Veterinary Medicine, Istanbul University- Cerrahpasa, İstanbul, Türkiye
• ⁹Department of Food Engineering, Faculty of Chemical Metallurgical Engineering, Istanbul Technical University, Istanbul, Türkiye
• ¹⁰Agronomic Engineering Department, Technical University of Cartagena, Cartagena, Spain
• ¹¹INRAE, UR 1268 BIA, Site de la Géraudière, B.P. 71627, Nantes, France
• ¹²Department of Paediatrics, The Medical University of Warsaw, Warsaw, Poland
• ¹³Food Engineering Department, Ege University, Izmir, Türkiye
• ¹⁴Faculty of Marine Sciences and Technology, Canakkale Onsekiz Mart University, Canakkale, Türkiye
• ¹⁵Immunology and Food Microbiology Group, Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, Olsztyn, Poland
• ¹⁶Department of Food Sciences & Nutrition, Faculty of Health Sciences, University of Malta, Malta, Malta
• ¹⁷Higher School of Technology, Mohammed V University of Rabat, Rabat, Morocco
• ¹⁸Department of Cellular and Molecular Biology, Abbes Laghrour University, Khenchela. Laboratory of Biotechnology and Food Quality, Institute of Nutrition, Food and Agri-Food Technologies, Khenchela, Algeria
• ¹⁹Department of Food Safety and Veterinary Public Health, National Veterinary and Food Institute, Faculty of veterinary medicine, University Ss Cyril and Methodius, Skopje, Skopje, North Macedonia
• ²⁰Department of Food Engineering, Çanakkale Onsekiz Mart University, Çanakkale, Türkiye
• ²¹Faculty of Health Sciences, Nutrition and Dietetics Department, Istanbul Aydin University, Istanbul, Türkiye
• ²²Department of Food Engineering, Manisa Celal Bayar University Faculty of Engineering and Natural Science, Manisa, Türkiye
• ²³Department of Food Engineering, Akdeniz University Faculty of Engineering, Antalya, Türkiye
• ²⁴UCA, INRAE, VetAgro Sup, UMRF, Aurillac, France
• ²⁵Institute for Biological Research Siniša Stanković, National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
• ²⁶Agroscope, Bern, Switzerland
• ²⁷Institute of Sciences of Food Production (ISPA)-National Research Council (CNR), Grugliasco, Italy

Abstract Introduction: Fermented foods are among the oldest foods produced and several different health benefits are attributed to their consumption even in the absence of concrete clinical evidence. To address this gap this systematic review focusses on the effects of consumption of fermented foods on food allergies. Methods: This systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and the relevant European Food Safety Authority guidelines. A systematic search strategy was established and registered in a study protocol in Open Science Framework. Scopus, MEDLINE and Cochrane Library were searched with specific strings targeting human studies focusing on Fermented food and food allergies. Inclusion and exclusion criteria were defined based on the People Intervention Comparison Outcome elements. Cadima tool was used to perform screening and selection of articles. A standard template was used for data extraction. Risk of bias assessment was performed using Risk of Bias 2.0 Tool, Risk of Bias in Non-randomized Studies - of Interventions, or Newcastle–Ottawa Scale protocols. Additionally, a narrative section was written based on The European Food Safety Authority guidelines for the mechanism of action and product characteristics for evidence support. Results: From a total of 558 initial records, ten studies were finally selected. Fermented foods evaluated were fermented soy products, baked goods, fruit-based beverages, vinegar-treated foods, oat-based drinks and dairy products (yogurt, cheese). In several studies, a reduced allergenicity was reported that was related to fermentation mediated hydrolysis of allergenic proteins of gluten or soy. Additional mechanisms were related to anti-allergic immunomodulatory effects or favorable shifts in gut microbiota composition. In one case, fermented food consumption led to aggravation of the allergic response presumably due to the compounds generated during soy fermentation. Risk of bias assessment revealed that most studies were performed with important methodological limitations. Conclusion: While fermented foods hold promise in reducing food allergenicity and promoting tolerance, current evidence is limited to draw solid conclusions. Rigorous, well-designed human clinical trials, complemented by mechanistic studies in vitro and in vivo are needed to clarify the role of fermented foods as dietary or even clinical tools to combat food allergies.