Lactobacillus Kefir
Also known as: Lactobacillus kefiri, Lb. plantarum, Kefir probiotics, Kefir lactobacilli
Overview
Lactobacillus kefiri is a key component of kefir, a fermented milk drink known for its probiotic properties. Kefir is a complex consortium of lactic acid bacteria (LAB), acetic acid bacteria, and yeasts, existing in a symbiotic relationship within a polysaccharide matrix. These microorganisms contribute to kefir's unique flavor and potential health benefits. While research is still emerging, particularly in human clinical trials, in vitro studies and some randomized controlled trials (RCTs) suggest promising effects. Kefir is typically sourced from milk or water kefir grains, which are used to inoculate the fermentation process. The evidence quality is considered Grade B, indicating strong mechanistic and preclinical data but limited RCTs. Further research is needed to fully validate its therapeutic potential.
Benefits
Lactobacillus kefiri and related kefir components exhibit several potential health benefits. Meta-analysis suggests significant antimicrobial effects against pathogens (OR 8.56, 95% CI: 2.27-32.21). Systematic reviews indicate that kefir may improve glycemic control, with RCTs showing a reduction in HbA1c (0.3-0.6%). Limited human trials suggest immunomodulatory effects, including increased IgA and IgG levels. In vitro studies demonstrate that certain strains, such as CIDCA 83114, can reduce Shigella invasion by up to 95%, suggesting a potential role in improving gut barrier function. These benefits are supported by varying levels of evidence, with antimicrobial effects and glycemic control having stronger support than immunomodulation.
How it works
Lactobacillus kefiri exerts its effects through several mechanisms. It competitively excludes pathogens in the gut, reducing their ability to colonize and cause infection. The fermentation process results in the production of short-chain fatty acids (SCFAs), which have various beneficial effects on gut health and overall metabolism. Additionally, L. kefiri can modulate TLR-2 and TLR-4 receptors, influencing the immune response. The bioavailability of L. kefiri is strain-dependent, with survival rates during gastric transit ranging from 0.1% to 30%.
Side effects
The consumption of Lactobacillus kefiri is generally considered safe, but some side effects have been reported. Mild bloating is a common side effect, occurring in 5-15% of participants in RCTs. In rare cases, particularly in immunocompromised individuals, there is a risk of fungemia. Theoretically, kefir could interact with warfarin due to vitamin K production. Kefir is contraindicated in individuals with severe immunosuppression or those with central venous catheters. It is important to exercise caution and consult with a healthcare professional before consuming kefir, especially if you have underlying health conditions or are taking medications.
Dosage
The effective dosage range for Lactobacillus kefiri, based on human trials, is 10^7 to 10^9 CFU/day. Live fermented milk is considered a more effective form than lyophilized products. It is recommended to consume kefir with meals to enhance the survival of the bacteria during gastric transit. For measurable effects, a minimum duration of 4 weeks is suggested. While specific upper limits are not well-defined, it is advisable to start with a lower dose and gradually increase it to assess tolerance. Consult with a healthcare professional for personalized dosage recommendations.
FAQs
Is there a difference between artisanal and commercial kefir?
Artisanal kefir may exhibit a higher odds ratio for antimicrobial effects compared to commercial products, potentially due to variations in microbial composition and fermentation processes.
Are there vegan options for kefir?
Water kefir is a vegan alternative, but it currently lacks the same level of clinical validation as milk kefir regarding its health benefits.
Does kefir need to be refrigerated?
Refrigeration is critical for maintaining the viability of live cultures in kefir. Temperatures above 4°C can lead to a significant reduction in the number of live bacteria.
Research Sources
- https://pmc.ncbi.nlm.nih.gov/articles/PMC8566050/ – Vieira et al.'s systematic review and meta-analysis of 45 studies demonstrated strong antimicrobial effects associated with kefir consumption (P<0.001). The study also highlighted that the bioactivity of kefir is strain-dependent, suggesting that different strains may have varying effects. A limitation noted was the heterogeneity in dosing across the included studies, ranging from 0.01 to 1000 mg/mL.
- https://www.cambridge.org/core/journals/nutrition-research-reviews/article/kefir-as-a-therapeutic-agent-in-clinical-research-a-scoping-review/227B92708C1ECBB04AF8D2BD0C06BDD6 – Rosa et al.'s scoping review of 21 clinical studies found that kefir improved glycemic control in 3 out of 5 RCTs. The review suggests that kefir may be a therapeutic agent for managing blood sugar levels. However, the authors noted that the durations of the included studies were relatively short, ranging from 2 to 12 weeks.
- https://academic.oup.com/nutritionreviews/article/81/3/267/6652871?login=false – Bourrie et al.'s systematic review focused on RCTs and found modest improvements in lipid profiles with kefir consumption, specifically LDL reductions of -8 to -15 mg/dL. The review suggests that kefir may have a beneficial impact on cardiovascular health. A limitation of the included studies was the small sample sizes, ranging from n=20 to 65.
- https://pmc.ncbi.nlm.nih.gov/articles/PMC6627492/ – This article discusses the general benefits and mechanisms of probiotics, including strains found in kefir. It highlights the role of probiotics in modulating the gut microbiota and immune system. The article emphasizes the importance of strain-specific effects and the need for further research to fully understand the potential health benefits of different probiotic strains.
- https://onlinelibrary.wiley.com/doi/abs/10.1155/2021/9081738 – This systematic review and meta-analysis examines the antimicrobial effects of kefir. It provides quantitative evidence supporting the use of kefir as an antimicrobial agent. The study also discusses the limitations of current research, such as the heterogeneity in dosing and study designs.
Supplements Containing Lactobacillus Kefir
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