Lactobacillus plantarum DR7 alleviated the symptoms of URTI by improving inflammatory parameters and enhancing immunomodulatory properties. In 109 adults (DR7, n = 56; placebo, n = 53), Lactobacillus plantarum DR7 reduced the duration of nasal symptoms and frequency of upper respiratory tract infections compared with the placebo over an administration period of 12-weeks. This was accompanied by reduced plasma inflammatory and oxidative stress levels in the DR7 group as compared to the placebo. The mechanisms involve enhanced plasma antioxidative properties, promotion of mucosal barrier integrity and activation of NK cells which are involved in innate immunity.