Daily supplements of a heat-killed Lactobacillus plantarum L-137 may reduce the incidence of upper respiratory tract infection (URTI), such as cold and flu, says a new study from Japan.
The study used the Immuno-LP20 supplement by House Wellness, based in Tokyo, and included 78 people specifically chosen for having been subjected to physical and psychological stress, which is known to disrupt the regulation of the immune system.
Data published in the Journal of Nutritional Science indicated that the supplement may be acting by augmenting immune functions.
House Wellness uses the heat killed Lactobacillus strain, which it calls HK L-137, as the active ingredient of Immuno-LP20. The heat treatment not only kills the cell, but stabilizes the cell walls, which is a key factor in the ingredient’s effectiveness, according to the company. Immuno-LP20 is commercially available in the US and was launched early this year.
‘Immunobiotic’, not probiotic
House Wellness previously told NutraIngredients-USA that dead bacteria have no ‘probiotics-like’ effects since probiotics are defined as live microbes which are beneficial for human health, and the characteristics of probiotics are that they proliferate in the gut and pump out beneficial metabolites and other byproducts.
“However, dead microbes have been also shown to exhibit beneficial effects that are equivalent to, or even greater than, live microbes. We have illustrated previously that cell wall condition of a live L-137, a key factor for stimulating immune cells, is unstable during storage periods even in a chilled condition, and its activity is attenuated by contact with digestive juices once it enters human body. We have also demonstrated that heat-treatment stabilizes cell wall of L-137 in good condition, and enhances immunomodulatory activity and stability in simulated digestive juices of L-137,” said the company.
And it is the stability of the cell walls that are the key to the ingredient’s effectiveness, it added. Much of the immune system interactions arise from components of those structures.
“The bacterial components such as peptidoglycans, teichoic acids, glycoproteins, lipoproteins and nucleic acids are known as immuno-stimulating molecules. We have shown that lipoteichoic acids on Lactobacillus plantarum cell surfaces correlate with its immunomodulatory activity,” said the company.
For the new study, scientists from House Wellness and Kyushu University recruited 78 people to participate in their randomized, double-blind, placebo-controlled, parallel study. Participants were assigned to receive either a tablet delivering 10 mg per day of HK L-137 or placebo for 12 weeks.
Using the Wisconsin Upper Respiratory Symptom Survey, the researchers found that the incidence of URTI symptoms were significantly reduced in the ‘immunobiotic’ group, compared to placebo. No significant differences were observed for duration, severity, and duration of medication between the two groups, they added.
Measures of immune function indicated significant increases in concanavalin A-induced proliferation of peripheral blood mononuclear cells like lymphocytes or macrophages in the Immuno-LP20 group, which indicated an augmentation of immune functions.
“Nevertheless, all endpoints showed significant negative correlations with duration of HK L-137 intake, suggesting that continued intake of HK L-137 appears to be effective for not only the incidence but also the symptoms of URTI,” said the researchers.
Source: Journal of Nutritional Science
Volume 2, e39, doi: 10.1017/jns.2013.35
“Oral intake of heat-killed Lactobacillus plantarum L-137 decreases the incidence of upper respiratory tract infection in healthy subjects with high levels of psychological stress”
Authors: Y. Hirose, Y. Yamamoto, Y. Yoshikai, S. Murosaki