TOKYOOral supplementation with probiotics decreased upper respiratory tract infection (URTI) in healthy subjects, new research in Journal of Nutritional Science found. Researchers from House Wellness Foods and Research Center for Infectious Diseases, Kyushu University, Kyushu, Japan examined the effects of heat-killed Lactobacillus plantarum L-137 (HK L-137) on URTI symptoms and immune function in healthy patients with high stress levels (Journal of Nutritional Science. 2013. doi:10.1017/jns.2013.35).

In the double blind, placebo-controlled study, 78 subjects took a tablet containing HK L-137 (10 mg) or placebo daily for 12 weeks. Researchers noted URTI symptoms daily using the Wisconsin Upper Respiratory Symptom Survey-21, in addition to monitoring immune functions such as concanavalin A-induced proliferation.

Researchers found URTI incidence was significantly lower in the immunobiotic HK L-137 group compared to the control group; concanavalin A-induced proliferation was significantly greater in the supplemented group.

"URTI incidence, duration and severity, and duration of medication showed significant negative correlations with duration of HK L-137 intake," researchers noted. "These findings suggest that daily HK L-137 intake can decrease URTI incidence in healthy subjects, possibly through augmentation of immune functions."