Effect of the Consumption of a Fermented Milk on Common Infections in Adults Submitted to Multi-stressor Situation

Inclusion Criteria: * male and female aged 18-29 years * attending 7 weeks of firemen training school * a 19 to 29 kg/m2 body mass index * found medically healthy (in particular, free of respiratory and GI tract symptoms) * agreeing to a written informed consent, and who appreciates dairy products and multi-fruit flavour. Exclusion Criteria: * Subject who is not reading and writing French, or not understanding informed consent or study protocol * subject with allergy or hypersensitivity to milk proteins or dairy foods components (ex: lactose), or with any known food or respiratory allergy; * subject presenting a severe evolutive or chronic pathology (Ex: cancer, tuberculosis, Crohn disease, cirrhosis, multiple sclerosis, Type I diabetes…) or any past or actual health condition that may interfere with the outcome of the study (Ex: HIV, Chemotherapy, malabsorption, ulcer, celiac disease…) * subject having experienced any infectious disease during the last 7 days * subject with current diarrhoea or constipation * subject who is frequently using laxatives or who has been using laxatives during the week prior his participation to the study * subject who was under artificial nutrition, had gastro-intestinal surgery or any intervention requiring general anaesthesia the last 2 months prior to his participation to the study * subject with special medicated diet (obesity, anorexia, metabolic pathology, nutritional complementation…) or with eating disorders (anorexia, bulimia, alcoholism…) * subject currently receiving, or who has received during the last months, systemic treatment or topical treatment likely to interfere with evaluation of the study parameters: antibiotics, antiseptics,antifungal, corticoids, vaccines, anti-histaminic molecules, non-corticoid anti-inflammatory substances, immunosuppressant treatment… * subject already enrolled in another clinical study, or currently under an exemption period from a previous study * female subject who is currently pregnant or breast-feeding, or willing to become pregnant during the 2 coming months after enrolment in the study * subject in a situation which in the investigator's opinion could interfere with optimal participation in the present study or could constitute a special risk for the subject