Efficacy of heat-killed Lactococcus lactis JCM 5805 on immunity and fatigue during consecutive high intensity exercise in male athletes: a randomized, placebo-controlled, double-blinded trial

Abstract

Background

Lactococcus lactis JCM 5805 (LC-Plasma) is a unique lactic acid bacteria (LAB) which activates plasmacytoid dendritic cells (pDC). We aimed to evaluate the effect of LC-Plasma on dendritic cell (DC) activity and subjective indices of upper respiratory tract infections (URTI) and fatigue in athletes under high intensity exercise.

Methods

We conducted a randomized, placebo-controlled, double-blinded trial. Fifty-one male subjects belonging to a university sports club were randomized into placebo (n = 25) and LC-Plasma (n = 26) groups. Individuals ingested placebo capsules containing cornstarch or LC-Plasma capsules containing 100 billion cells of heat-killed LC-Plasma per day for 13 days. During the intervention period, subjects performed high intensity exercise according to their sports club training regime. Blood and saliva sampling were obtained at days 1 and 14, and physical conditions were recorded in a diary. We investigated expression of maturation markers on DCs, muscle damage and stress markers and used student’s t test adjusted by Bonferoni’s method for multiple comparison between groups. These data were presented as mean ± SD. We also investigated cumulative days of symptoms regarding infections and fatigue and used Chi-square test for comparison between groups. These data were presented as cumulative number.

Results

CD86 as maturation marker on pDC was significantly increased in the LC-Plasma group at day 14 (Placebo: 296 ± 70 vs. LC-Plasma: 365 ± 115; Mean Fluorescent Intensity; p = 0.013). Cumulative days of URTI were significantly lower in the LC-Plasma group (Placebo: URTI positive 56, URTI negative 256 vs. LC-Plasma: URTI positive 39, URTI negative 299; days; p = 0.028) and symptoms like sneeze or running nose were significantly lower in the LC-Plasma group (Placebo: Symptom positive 52, Symptom negative 258, vs. LC-Plasma: Symptom positive 36, Symptom negative 301; days; p = 0.032). Moreover, the cumulative days of fatigue were significantly fewer in the LC-Plasma group (Placebo: Symptom positive 128, Symptom negative 182, vs. LC-Plasma: Symptom positive 110, Symptom negative 225; days; p = 0.032). Markers of muscle damage and stress markers were not significantly different between groups.

Conclusion

We consider that heat-killed LC-Plasma supplementation relieves morbidity and symptoms of URTI via activation of pDC and decreases fatigue accumulation during consecutive high intensity exercise in athletes. However, LC-Plasma ingestion did not affect markers of muscle damage and stress.

Trial registration

UMIN-CTR, UMIN000020372. Registered 28 December 2015.

Keywords:

• Dendritic cells
• High intensity exercise
• LC-plasma
• Upper respiratory tract infections
• Fatigue

Acknowledgements

We thank Takumi Horiike, Akira Nakamura, Shunsuke Nagato who were supervisor of Juntendo University sports clubs for good partnership in this study. We also thank Dr. Tetsuro Miyazaki, Dr. Tomoyuki Shiozawa, Dr. Shuhei Takahashi, and Dr. Tomoyasu Kadoguchi of Juntendo University and Dr. Osamu Kanauchi, and Dr. Keiji Kondo of Kirin Co., Ltd. for valuable discussions and technical supports.

Funding

This study was funded by Kirin Co., Ltd.

Availability of data and materials

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Authors’ contributions

YK, HN, KS, and HD conceived and designed the experiments. YK, KF, and YI performed the experiments. YK, KF, and YI analyzed the data. YK, TF, TK, and KS wrote the manuscript. All authors read and approved the final manuscript.

Ethics approval and consent to participate

The study protocol was ethically reviewed and approved by the institution review board at Juntendo University (15–057), Tokyo, Japan and carried out in accordance with the principles outlined in the 2002 Declaration of Helsinki of the World Medical Association. This study was registered at the University Hospital Medical Information Network Clinical Trials Registry as UMIN000020372.

Consent for publication

Not applicable.

Competing interests

Y.K., T.F., and T.K. are employees of Kirin Co., Ltd. The authors declare that they have no competing interests.

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