{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T14:50:59Z","timestamp":1791298259231,"version":"4.1.0"},"reference-count":38,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2026,6,4]],"date-time":"2026-06-04T00:00:00Z","timestamp":1780531200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Microorganisms"],"abstract":"<jats:p>Upper respiratory tract infections (URTI) are highly prevalent worldwide. Although probiotics have shown potential in preventing URTI, evidence in healthy adults remains limited. Lacticaseibacillus rhamnosus CRL 1505 is a strain with immunomodulatory effects in preclinical studies and benefits in healthy children. Based on this evidence, a randomized, double-blind, placebo-controlled, parallel-group clinical trial was conducted in healthy adults, receiving either L. rhamnosus CRL 1505 (1 bln\/day) or placebo for 12 weeks, with a 4-week follow-up. The primary endpoint was the proportion of participants experiencing URTI episodes (at least one, two, or three episode(s)). The secondary endpoints included: number and duration of URTI episodes, URTI-free time, symptom severity, use of symptomatic medication, salivary IgA levels, and safety outcomes. Results show that L. rhamnosus CRL 1505 significantly reduced the number of participants experiencing \u22653 URTI episodes at 16 weeks compared with placebo. The probiotic group experienced fewer URTI episodes per participant, a shorter cumulative duration of URTIs, and a higher URTI-free time rate. Probiotic supplementation significantly reduced the use of symptomatic medications. In conclusion, daily supplementation with L. rhamnosus CRL 1505 reduced the burden of URTI in healthy adults, specifically of those experiencing more episodes, by decreasing infection frequency, duration, and medication use.<\/jats:p>","DOI":"10.3390\/microorganisms14061270","type":"journal-article","created":{"date-parts":[[2026,6,4]],"date-time":"2026-06-04T17:11:04Z","timestamp":1780593064000},"page":"1270","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Randomized, Double-Blind, Placebo-Controlled Clinical Trial Assessing the Efficacy of Lacticaseibacillus rhamnosus CRL 1505 in Preventing Upper Respiratory Tract Infections in Healthy Adults"],"prefix":"10.3390","volume":"14","author":[{"given":"Valentina","family":"Taverniti","sequence":"first","affiliation":[{"name":"Sacco Srl, Alessandro Manzoni Street, 29\/A, 22071 Cadorago, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ines","family":"Martinez","sequence":"additional","affiliation":[{"name":"Sacco Srl, Alessandro Manzoni Street, 29\/A, 22071 Cadorago, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Beatrice","family":"Tavazzani","sequence":"additional","affiliation":[{"name":"Sacco Srl, Alessandro Manzoni Street, 29\/A, 22071 Cadorago, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2814-413X","authenticated-orcid":false,"given":"Carlos","family":"Baeza-Mart\u00ednez","sequence":"additional","affiliation":[{"name":"Servicio de Neumolog\u00eda, Hospital Universitario de Elche, 03203 Alicante, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Francisco","family":"L\u00f3pez-Garcia","sequence":"additional","affiliation":[{"name":"Servicio de Medicina Interna, Hospital Universitario de Elche, 03203 Alicante, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Carmen","family":"Carazo-D\u00edaz","sequence":"additional","affiliation":[{"name":"Applied Statistical Methods in Medical Research Group, Catholic University of Murcia (UCAM), 30107 Murcia, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Juan Aguera","family":"Santos","sequence":"additional","affiliation":[{"name":"Human Microbiome Research Group, Universidad Cat\u00f3lica San Antonio de Murcia (UCAM), 30107 Murcia, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4941-4960","authenticated-orcid":false,"given":"Julio","family":"Villena","sequence":"additional","affiliation":[{"name":"Reference Center for Lactobacilli [CERELA-CONICET], Chacabuco 145, San Miguel de Tucum\u00e1n T4000ILC, Argentina"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9571-1259","authenticated-orcid":false,"given":"Susana","family":"Salva","sequence":"additional","affiliation":[{"name":"Reference Center for Lactobacilli [CERELA-CONICET], Chacabuco 145, San Miguel de Tucum\u00e1n T4000ILC, Argentina"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mar\u00eda P\u00eda","family":"Taranto","sequence":"additional","affiliation":[{"name":"Reference Center for Lactobacilli [CERELA-CONICET], Chacabuco 145, San Miguel de Tucum\u00e1n T4000ILC, Argentina"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Susana","family":"\u00c1lvarez","sequence":"additional","affiliation":[{"name":"Reference Center for Lactobacilli [CERELA-CONICET], Chacabuco 145, San Miguel de Tucum\u00e1n T4000ILC, Argentina"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Graciela","family":"Font","sequence":"additional","affiliation":[{"name":"Reference Center for Lactobacilli [CERELA-CONICET], Chacabuco 145, San Miguel de Tucum\u00e1n T4000ILC, Argentina"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3731-9827","authenticated-orcid":false,"given":"Vicente","family":"Navarro-L\u00f3pez","sequence":"additional","affiliation":[{"name":"Human Microbiome Research Group, Universidad Cat\u00f3lica San Antonio de Murcia (UCAM), 30107 Murcia, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,6,4]]},"reference":[{"key":"ref_1","unstructured":"GBD 2021 Upper Respiratory Infections Otitis Media Collaborators (2024). 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