Gut Microbiome Response to Long-Haul Travel in Elite Football Players

Inclusion Criteria: * Male professional footballers who are involved in regular training during the pre-season period. * Generally healthy, with no acute or chronic illnesses that could interfere with the study intervention or outcomes. * Not currently consuming probiotics, prebiotics, or antibiotics within 4 weeks prior to enrolment. * Willing to refrain from starting any new dietary supplements or probiotics during the study period. * Able and willing to provide written informed consent. Exclusion Criteria: * History of gastrointestinal disorders (e.g., Crohn's disease, ulcerative colitis, irritable bowel syndrome) or chronic diseases that could interfere with probiotic metabolism or study outcomes. * Acute illness (e.g., infection) within 2 weeks prior to enrollment. * Known allergy or hypersensitivity to components of the probiotic or placebo. - - - Use of antibiotics, probiotics, prebiotics, or synbiotics within 4 weeks prior to study start. * Use of immunosuppressive medications or other supplements likely to impact gut microbiota. * Regular use of alcohol or drugs at levels that could interfere with study participation or outcomes. * Participation in another clinical trial within the past 3 months. * Any injury or medical condition that limits participation in full training or matches during the study period.