Fermented Milk Drink With Lacticaseibacillus Paracasei Strain Shirota Helps Triathletes With Cold-Like Symptoms Before and After a Race

This study aims to evaluate whether a fermented milk drink containing the probiotic strain Lacticaseibacillus paracasei strain Shirota (LCS), commonly found in Yakult®, can help reduce upper respiratory symptoms in triathletes before and after competition. Athletes often experience cold-like symptoms due to physical stress, intense training, and immune system challenges. The study investigates whether daily consumption of this probiotic drink can help improve immune response and reduce the incidence or severity of symptoms such as sore throat, nasal congestion, or coughing. This is a randomized, double-blind, placebo-controlled, parallel-group study involving healthy adult triathletes. Participants will be randomly assigned to receive either the probiotic drink or a placebo for a specific period before and after a triathlon event. Symptoms and health markers will be tracked through questionnaires and biological samples. The goal is to explore whether probiotic supplementation can provide practical, non-pharmacological support for athletes' immune health and well-being during intense physical activity.

Inclusion Criteria: * Aged between 20 and 60 years. * Amateur triathletes with regular endurance training and prior competition experience. * In good general health, with no history of chronic diseases or conditions affecting immune or inflammatory responses. * Willing and able to comply with all study procedures, including sample collections and completion of validated questionnaires at five time points. * Agree to consume a daily dose of fermented milk containing Lacticaseibacillus paracasei strain Shirota (LcS) or placebo from 30 days before until 14 days after the competition. * No use of probiotics, antibiotics, or immunomodulatory supplements in the 30 days prior to enrollment Exclusion Criteria: * Known allergy or intolerance to dairy products, including lactose. * Use of probiotics or antibiotics within 30 days prior to enrollment. * Current use of any pharmacological treatment. * History of chronic rhinopathy. * Diagnosis of autoimmune disease. * History of recurrent infections not involving the upper airway. * Presence of major medical conditions or chronic diseases, including but not limited to respiratory or gastrointestinal disorders. * Incomplete or missing data necessary for determining eligibility or for study outcomes.