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. 2021 Feb 25;11(3):136.
doi: 10.3390/metabo11030136.

The Effect of Kefir Supplementation on Improving Human Endurance Exercise Performance and Antifatigue

Mon-Chien Lee  1 , Wei-Lun Jhang  1 , Chia-Chia Lee  2 , Nai-Wen Kan  3 , Yi-Ju Hsu  1 , Chin-Shan Ho  1 , Chun-Hao Chang  1 , Yi-Chen Cheng  2 , Jin-Seng Lin  2 , Chi-Chang Huang  1
Affiliations

The Effect of Kefir Supplementation on Improving Human Endurance Exercise Performance and Antifatigue

Mon-Chien Lee et al. Metabolites. .

Abstract

Kefir is an acidic, carbonated, and fermented dairy product produced by fermenting milk with kefir grains. The Lactobacillus species constitutes an important part of kefir grains. In a previous animal study, kefir effectively improved exercise performance and had anti-fatigue effects. The purpose of this research was to explore the benefits of applying kefir to improve exercise performance, reduce fatigue, and improve physiological adaptability in humans. The test used a double-blind crossover design and supplementation for 28 days. Sixteen 20-30 year-old subjects were divided into two groups in a balanced order according to each individual's initial maximal oxygen uptake and were assigned to receive a placebo (equal flavor, equal calories, 20 g/day) or SYNKEFIR™ (20 g/day) every morning. After the intervention, there were 28 days of wash-out, during which time the subjects did not receive further interventions. After supplementation with SYNKEFIR™, the exercise time to exhaustion was significantly greater than that before ingestion (p = 0.0001) and higher than that in the Placebo group by 1.29-fold (p = 0.0004). In addition, compared with the Placebo group, the SYNKEFIR™ administration group had significantly lower lactate levels in the exercise and recovery (p < 0.05). However, no significant difference was observed in the changes in the gut microbiota. Although no significant changes in body composition were found, SYNKEFIR™ did not cause adverse reactions or harm to the participants' bodies. In summary, 28 days of supplementation with SYNKEFIR™ significantly improved exercise performance, reduced the production of lactic acid after exercise, and accelerated recovery while also not causing any adverse reactions.

Keywords: exercise performance; fatigue; kefir.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Effects of SYNKEFIR™ supplementation on the time to exhaustion. Data are shown as the mean ± SD, n = 16 subjects/group. Intergroup differences were analyzed by two-way repeated measures ANOVA post hoc Bonferroni test. ** p < 0.01, *** p < 0.001.
Figure 2
Figure 2
Effects of SYNKEFIR™ supplementation on the (A) lactate, (B) NH3, (C) CK, and (D) glucose serum levels during and after exercise. Data are shown as the mean ± SD. Statistical differences between groups at same time point were analyzed using Student’s unpaired t-test. * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001.
Figure 3
Figure 3
The levels of (A) Lactobacillus spp., (B) Bifidobacterium spp., (C) Clostridium spp., and (D) Bacteroides spp. were analyzed using qPCR method in fecal samples from subjects with Placebo or SYNKEFIR™ supplementation. Data are shown as the mean ± SD. Intergroup differences were analyzed by two-way repeated measures ANOVA post hoc Bonferroni test. * p < 0.05.
Figure 4
Figure 4
Experimental procedure description.
Figure 5
Figure 5
Experimental design.
See this image and copyright information in PMC

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