Clinical Trial to Evaluate the Efficacy of a Probiotic Preparation in the Prevention of Upper Respiratory Tract Infections in Adults

Inclusion Criteria: * Healthy men and women between 18 and 65 years. * Signed Informed Consent to participate in the study * BMI less than 35 kg/m2 Exclusion Criteria: * Chronic pathological conditions such as chronic respiratory diseases (asthma, chronic bronchitis, chronic obstructive pulmonary disease etc), chronic heart diseases (chronic heart failure etc), chronic neurological diseases (Parkinson´s diseases, multiple esclerosis etc), chronic liver diseases, kidney liver diseases, gastrointestinal diseases, hematologic disorders etc, or other disease or condition that the researcher considers * Metabolic disorders (diabetes, obesity with BMI greater than 35.1 kg/m2 etc). * Congenital or acquired immune defects (including allergies). * Immunocompromised individuals (HIV infection, chemotherapy, post-trasplant, chronic corticosteroid treatment etc). * Presence of nasal ulcers/nasal polyps or other conditions that could cause nasal obstruction. * Abuse of alcohol, tobacco or other drugs. * Pregnancy or lactation. * Regular intake of products that could influence the study outcome (immune suppressants/immune stimulants including paramedication such as Echinacea, analgesics, antiinflammatories, antitussives/expectorants, influenza remedies, mouth or throat therapeutics, decongestants, antibiotics, antihistaminergic drugs, probiotics) within the last 4 weeks prior to the study start. * Influenza vaccination in the last 6 monts.