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Lactobacillus keffir

Also known as: Lactobacillus kefiri, Lactobacillus kefir, Lacticaseibacillus kefiri

Overview

Lacticaseibacillus kefiri (formerly Lactobacillus kefiri) is a species of lactic acid bacteria and a key probiotic microorganism naturally found in kefir, a traditional fermented milk beverage originating from the Caucasus region. It is a dominant Lactobacillus species within the symbiotic culture of bacteria and yeasts that constitute kefir grains. L. kefiri produces lactic acid and various bioactive compounds, including exopolysaccharides like kefiran, which are believed to contribute to its probiotic effects. Primarily, L. kefiri is utilized to support gut health, modulate the immune system, and potentially improve metabolic parameters such as blood glucose and lipid profiles. It is also being investigated for its antimicrobial properties against various pathogens. While research specifically on isolated L. kefiri is emerging, most clinical evidence regarding its benefits is derived indirectly from studies on whole kefir consumption, which contains a complex microbial community.

Benefits

Kefir consumption, which includes L. kefiri, has been associated with several health benefits. Meta-analyses suggest modest reductions in fasting blood glucose levels, indicating potential benefits for glycemic control in individuals with metabolic syndrome or type 2 diabetes. For instance, studies have shown statistically significant but clinically moderate improvements in fasting glucose. There is also evidence that kefir may reduce oral Streptococcus mutans, thereby lowering the risk of dental caries, and could assist in Helicobacter pylori eradication. Limited data suggest potential improvements in lipid profiles and blood pressure, though these findings require further confirmation through more robust studies. Additionally, L. kefiri and other kefir microbes produce bioactive compounds, such as exopolysaccharides like kefiran, which are thought to contribute to antimicrobial and immune-modulatory effects. Preclinical models have shown potential anti-inflammatory effects, but human data are currently sparse. Benefits have primarily been studied in adults with metabolic syndrome, type 2 diabetes, or oral infections, with safety and efficacy in other populations needing more research.

How it works

Lacticaseibacillus kefiri primarily exerts its effects within the gastrointestinal tract. It contributes to a balanced gut microbiota by producing lactic acid, which lowers the gut pH and creates an unfavorable environment for the growth of pathogenic bacteria. L. kefiri also produces various bioactive molecules, including exopolysaccharides like kefiran, which are believed to modulate immune responses. As a live probiotic, it transiently colonizes the gut, where its metabolites and cellular components interact with gut epithelial cells and immune cells (e.g., macrophages, dendritic cells). These interactions can enhance the gut barrier function, influence the composition of the gut microbiota, and modulate systemic inflammation and metabolic pathways. The effects are localized within the gut, as the bacteria themselves are not absorbed systemically.

Side effects

Kefir and its microbial components, including Lacticaseibacillus kefiri, are generally considered safe for consumption by healthy individuals. The most common side effects are mild gastrointestinal symptoms, such as bloating or gas, which may occur initially as the body adjusts to the probiotic. These symptoms are typically transient and resolve with continued use. Uncommon side effects include rare allergic reactions in sensitive individuals. Serious adverse events have not been reported in reviewed randomized controlled trials. There are no significant drug interactions documented for L. kefiri. However, caution is advised for immunocompromised patients or individuals with severe milk protein allergies, as the safety data in these populations are limited. Similarly, there is limited data on the use of L. kefiri in pregnant women and infants, warranting caution and consultation with a healthcare provider before use in these groups.

Dosage

The minimum effective dose for isolated Lacticaseibacillus kefiri has not been well-established, as most research focuses on the consumption of whole kefir. Clinical studies typically use 100-200 mL/day of fermented milk kefir, which contains a complex microbial community including L. kefiri. The standard dosage range for kefir consumption in clinical studies is generally between 100 to 500 mL daily. There is no reported toxicity at typical dietary intake levels, and thus, no maximum safe dose has been determined. For sustained benefits, regular daily consumption is recommended. It is important to note that traditionally fermented milk kefir is often preferred over industrial variants due to its greater microbial diversity. The survival of L. kefiri through gastric acidity is crucial for its efficacy, and the kefir matrix may offer some protection to the probiotic bacteria. No specific cofactors are identified as necessary, but consuming kefir with food may improve tolerance.

FAQs

Is Lactobacillus kefiri supplementation safe?

Yes, Lacticaseibacillus kefiri, when consumed as part of kefir, is generally considered safe for healthy individuals, with mild and transient gastrointestinal side effects being the most common.

Can L. kefiri alone provide health benefits?

Most evidence for health benefits comes from studies on whole kefir, which contains a complex microbial community. More research is needed to confirm the specific effects of isolated L. kefiri.

How long does it take to see benefits?

Benefits from L. kefiri, primarily through kefir consumption, may become apparent after several weeks of consistent, regular use.

Does kefir help with blood sugar control?

Some research suggests that kefir consumption, containing L. kefiri, may lead to modest improvements in fasting blood glucose levels, particularly in individuals with metabolic syndrome or type 2 diabetes.

Are there risks for immunocompromised people?

Caution is advised for immunocompromised individuals when considering L. kefiri or kefir consumption. It is crucial to consult with healthcare providers before use.

Research Sources

https://www.mdpi.com/2304-8158/14/12/2077 – This systematic review and meta-analysis of preclinical studies investigated the effects of bioactive compounds in kefir. It found that these compounds, including those from L. kefiri, can reduce inflammation and markers associated with metabolic syndrome in animal and in vitro models. The study highlights the potential therapeutic properties of kefir's components, though it notes the need for human translation.
https://academic.oup.com/nutritionreviews/article/81/3/267/6652871?login=false – This systematic review of randomized controlled trials (RCTs) on kefir consumption, which includes L. kefiri, suggests potential benefits such as reductions in fasting glucose, oral pathogens, and assistance in H. pylori eradication. While generally safe, the review points out that many included studies had a high risk of bias, heterogeneity, and small sample sizes, indicating a need for more rigorous research.
https://www.cambridge.org/core/journals/nutrition-research-reviews/article/kefir-as-a-therapeutic-agent-in-clinical-research-a-scoping-review/227B92708C1ECBB04AF8D2BD0C06BDD6 – This scoping review of 44 clinical studies on kefir's therapeutic potential found that kefir is generally safe and may offer benefits for metabolic, gastrointestinal, and dental health. However, the review emphasized the variability in study methodologies, small sample sizes, and a lack of standardized dosing, underscoring the need for more consistent and well-designed clinical trials.