Effect of Daily Intake of Heat-Killed Lactobacillus plantarum HOKKAIDO on Immunocompetence: A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Study

Abstract

Background: Consumption of Lactobacillus plantarum HOKKAIDO (HOKKAIDO strain) reportedly increases immunocompetence. However, the concentration of viable bacteria and the type of food they can be incorporated into limits their consumption. The study aims to demonstrate the effect of daily intake of the heat-killed L. plantarum HOKKAIDO strain (HK-HOKKAIDO strain; 5 × 1010 colony-forming units/day) by healthy subjects with low natural killer (NK) cell activity for 8 weeks.Method: In this randomized, double-blind, placebo-controlled, parallel-group study, 70 healthy Japanese subjects who showed relatively low NK cell activity were recruited and randomly assigned to the HK-HOKKAIDO strain or placebo group. All subjects ingested one capsule per day for 8 weeks. We conducted medical interviews and performed body composition measurements, vital sign examinations, and blood sampling at weeks 0 (baseline), 4, and 8, and we collected salivary samples at weeks 0 and 8. In addition, the frequency and severity of cold symptoms in the subjects were recorded daily during the intake period.Results: Intake of the HK-HOKKAIDO strain did not increase the NK cell activity or immunity marker levels, including those of immunoglobulin, leukocyte fraction, and salivary secretory immunoglobulin A. However, the frequency and severity of the common cold symptoms were significantly reduced after the daily consumption of the HK-HOKKAIDO strain.Conclusions: The results showed that HK-HOKKAIDO strain administration can decrease the frequency and severity of common cold symptoms in healthy subjects. Our findings support the use of the HK-HOKKAIDO strain as a functional food with health benefits.Clinical trial registration: UMIN000034822

Effect of Probiotics on Common Cold, Influenza, and Influenza-Like Illness

“…Among the 20 included articles, 9 involved healthy children or infants,22,23,27–33 and the remaining articles addressed healthy adults 10,14,21,34–41. Most of the studies were conducted in Japan,14,27,32,34–36,39 Croatia,23,28 Thailand,29,33 North America,10,37 and 7 in other Asian or European countries 21,22,30,31,38,40,41. The probiotic products administered among these trials included Lactobacillus acidophilus ,10,14,22,27,29,29,31,34–36,38–40 Bifidobacterium animalis spp.…”

“…Most of the studies were conducted in Japan,14,27,32,34–36,39 Croatia,23,28 Thailand,29,33 North America,10,37 and 7 in other Asian or European countries 21,22,30,31,38,40,41. The probiotic products administered among these trials included Lactobacillus acidophilus ,10,14,22,27,29,29,31,34–36,38–40 Bifidobacterium animalis spp. Lactis ,23,28,37 or a mixture of several probiotic strains as symbiotic 21,30,33,41.…”

“…Twelve studies reported the incidence of the common cold 14,21–23,28,33–36,38,39,41. A significant reduction was observed in the common cold episodes after the probiotic supplementation (random-effects model, OR = 0.58, 95% CI: 0.44-0.76, P < .001).…”

“…The number of participants was not segregated on the basis of gender. Eleven studies reported incidence of the common cold, 22,[28][29][30][33][34][35][37][38][39][40] 4 studies reported incidence of influenza and the common cold, 10,14,23,27 2 studies assessed the incidence of the common cold and influenza-like illness, 21,41 2 studies assessed the incidence of the influenza or influenza-like illness separately, 31,32 and 1 reported the incidence of influenza-like illness and influenza. 10 Two parallel trials with different patient numbers were published in the same article.…”

In vitro evaluation of Lactiplantibacillus plantarum HOKKAIDO strain, effective lactic acid bacteria for calf diarrhea

“…Lp-HKD induces the production of interleukin (IL)-6, IL-10, IL-12, and tumor necrosis factor-α (TNF-α) by human dendritic cells ( 5 ). Furthermore, a previous study reported that heat-killed Lp-HKD alleviated clinical symptoms of the common cold in humans ( 6 ). Therefore, Lp-HKD is expected to improve antiviral immune function in humans.…”