Carla P Vieira, Anisio Iuri L S Rosario, Carini A Lelis, Bruna Samara S Rekowsky, Anna Paula A Carvalho, Denes Kaic A Rosário, Thaísa A Elias, Marion P Costa, Debora Foguel, Carlos A Conte-Junior
Journal: Oxidative medicine and cellular longevity 2022;2021():9081738
PMID: 34745425
Kefir – such as milk kefir, is the result of fermentation by a symbiotic complex of microorganisms that make up kefir grains. Lactic bacteria and acetic acid bacteria are the predominant species of this complex. An abundance of evidence speaks about the health benefits of kefir consumption. However, the identification of the bioactive compounds and controlled experiments are limited. This systematic review and meta-analysis sought to gather the current evidence on the health-promoting qualities and bioactive compounds from kefir consumption. Included were in-vitro and in-vivo studies encompassing 88 papers for the review and 45 papers for the meta-analysis. The authors looked at bioactive compounds in kefir and their antimicrobial and antioxidant activity. Before examining the impact of kefir on gut microbiome composition, the immune system, its anticancer properties, kefir's effects on fat metabolism, blood pressure, neurodegenerative diseases and osteoporosis. It also considered whether kefir from industrial production with a previously selected starter culture and artisanal kefir, using grains, exhibit different functional benefits. In conclusion, kefir has various bioactive compounds and this meta- analysis affirms it's health promoting benefits. Kefir and its compounds demonstrate antimicrobial, anticancer, and immune modulating properties. And artisanal kefir is associated with a more diverse microbial profile resulting in a wider array of bioactive compounds and antioxidant potential. How these bioactive compounds from kefir exert their effects is complex and hence the authors advocate for more standardised methodologies in future studies to strengthen existing findings.
Despite evidence of health benefits from kefir administration, a systematic review with meta-analysis on bioactive compounds associated with these benefits is still absent in the literature. Kefir is fermented milk resulting from the metabolism of a complex microbiota in symbiosis. Recent researches have investigated the bioactive compounds responsible for the preventive and therapeutic effects attributed to kefir. However, differences in functional potential between industrial and artisanal kefir are still controversial. Firstly, we identified differences in the microbial composition among both types of kefir. Available evidence concerning the action of different bioactive compounds from kefir on health, both from and studies, was subsequently summarized to draw a primary conclusion of the dose and the intervention time for effect, the producer microorganisms, the precursor in the milk, and the action mechanism. Meta-analysis was performed to investigate the statistically significant differences ( < 0.05) between intervention and control and between both types of kefir for each health effect studied. In summary, the bioactive compounds more commonly reported were exopolysaccharides, including kefiran, bioactive peptides, and organic acids, especially lactic acid. Kefir bioactive compounds presented antimicrobial, anticancer, and immune-modulatory activities corroborated by the meta-analysis. However, clinical evidence is urgently needed to strengthen the practical applicability of these bioactive compounds. The mechanisms of their action were diverse, indicating that they can act by different signaling pathways. Still, industrial and artisanal kefir may differ regarding functional potential-OR of 8.56 (95% CI: 2.27-32.21, ≤ .001)-according to the observed health effect, which can be associated with differences in the microbial composition between both types of kefir.
Copyright © 2021 Carla P. Vieira et al.
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