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Bioactive Compounds from Kefir and Their Potential Benefits on Health: A Systematic Review and Meta-Analysis.
Vieira, CP, Rosario, AILS, Lelis, CA, Rekowsky, BSS, Carvalho, APA, Rosário, DKA, Elias, TA, Costa, MP, Foguel, D, Conte-Junior, CA
Oxidative medicine and cellular longevity. 2021;2021:9081738
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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.
Abstract
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 in vitro and in vivo 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 (P < 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, P ≤ .001)-according to the observed health effect, which can be associated with differences in the microbial composition between both types of kefir.
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Implications of the vaginal microbiome and potential restorative strategies on maternal health: a narrative review.
Moumne, O, Hampe, ME, Montoya-Williams, D, Carson, TL, Neu, J, Francois, M, Rhoton-Vlasak, A, Lemas, DJ
Journal of perinatal medicine. 2021;49(4):402-411
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The vaginal microbiome is a complex community of bacteria that maintains and contributes to vaginal health and works together to protect the host from disease. Lactobacilli are the predominant species in a healthy vaginal microbiome. This review sought to summarize current evidence on how changes in the vaginal microbiome composition before and throughout pregnancy influence and contribute to several health conditions. The authors investigated the role of the vaginal microbiome in fertility and in-vitro fertilization (IVF), where evidence is still conflicting, followed by conditions that can present during pregnancy such as preterm labour, gestational diabetes, and preeclampsia. In preterm labour, lower levels of Lactobacillus and its D-lactic acid secretions have been observed as a common denominator; in gestational diabetes, it remains unclear whether the changes in the vaginal microbiome associated with the condition are causative or rather a result of the condition. Little research has been done regarding preeclampsia, but initial studies indicate there may be a link between the condition and the vaginal microbiome. The authors also reviewed the evidence on methods of restoring vaginal health, including oral and vaginally applied probiotics as well as vaginal microbiome transplants (VMT) - the transfer of vaginal secretions from a healthy donor. The paper discusses the evidence on the use of oral and locally applied probiotics for the aforementioned conditions, and the promising potential of VMTs alongside the risks and regulatory challenges that come with it. This review provides a helpful summary of the current understanding of the role of the vaginal microbiome in fertility and throught pregnancy.
Abstract
The vaginal microbiome undergoes dramatic shifts before and throughout pregnancy. Although the genetic and environmental factors that regulate the vaginal microbiome have yet to be fully elucidated, high-throughput sequencing has provided an unprecedented opportunity to interrogate the vaginal microbiome as a potential source of next-generation therapeutics. Accumulating data demonstrates that vaginal health during pregnancy includes commensal bacteria such as Lactobacillus that serve to reduce pH and prevent pathogenic invasion. Vaginal microbes have been studied as contributors to several conditions occurring before and during pregnancy, and an emerging topic in women's health is finding ways to alter and restore the vaginal microbiome. Among these restorations, perhaps the most significant effect could be preterm labor (PTL) prevention. Since bacterial vaginosis (BV) is known to increase risk of PTL, and vaginal and oral probiotics are effective as supplemental treatments for BV prevention, a potential therapeutic benefit exists for pregnant women at risk of PTL. A new method of restoration, vaginal microbiome transplants (VMTs) involves transfer of one women's cervicovaginal secretions to another. New studies investigating recurrent BV will determine if VMTs can safely establish a healthy Lactobacillus-dominant vaginal microbiome. In most cases, caution must be taken in attributing a disease state and vaginal dysbiosis with a causal relationship, since the underlying reason for dysbiosis is usually unknown. This review focuses on the impact of vaginal microflora on maternal outcomes before and during pregnancy, including PTL, gestational diabetes, preeclampsia, and infertility. It then reviews the clinical evidence focused on vaginal restoration strategies, including VMTs.
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The Effect of Kefir Supplementation on Improving Human Endurance Exercise Performance and Antifatigue.
Lee, MC, Jhang, WL, Lee, CC, Kan, NW, Hsu, YJ, Ho, CS, Chang, CH, Cheng, YC, Lin, JS, Huang, CC
Metabolites. 2021;11(3)
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Compared to sedentary people, athletes exhibit a much more abundant and diverse composition of gut bacteria. Hence the relationship between gut microbes and energy usage and exercise performance has attracted much attention in recent years. Probiotics and prebiotic-related products have demonstrated the potential to enhance metabolic pathways and influence energy levels, energy consumption and exercise performance. And previous studies demonstrated positive effects on exercise endurance associated with the consumption of kefir, a fermented dairy product containing Lactobacilli species as part of the microbial symbiosis. This study investigated whether kefir can promote changes in the gut microbiota, improve exercise endurance performance, and influences fatigue during and after exercise. The study enrolled sixteen, untrained 20–30-year-old for a double-blind crossover design study, supplementing with SYNKEFIR™ for 28 days whilst observing changes in metabolic markers, body composition, exercise endurance and faecal gut bacteria. In summary, supplementation with SYNKEFIR™ significantly improved exercise performance and reduced the production of lactic acid after exercise. In addition, kefir supplementation seemed to reduce fatigue and accelerated the recovery from fatigue after exercise, with a marked reduction in lactic acid production after exercise. Though kefir supplementation had no significant effect on other post-exercise fatigue biochemical indicators nor did it induce notable changes in gut bacteria composition. As SYNKEFIR™ is a starter culture isolated from traditional kefir it could be expected that other traditional kefir products would have similar effects. Kefir as a food product is suited to a wide range of people, and it could be considered part of a healthy diet plan for untrained individuals wishing to support their exercise performance.
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.
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Four weeks of probiotic supplementation reduces GI symptoms during a marathon race.
Pugh, JN, Sparks, AS, Doran, DA, Fleming, SC, Langan-Evans, C, Kirk, B, Fearn, R, Morton, JP, Close, GL
European journal of applied physiology. 2019;119(7):1491-1501
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Gastrointestinal (GI) symptoms are common in athletes participating in marathon running. The purpose of this study was to evaluate the effects of probiotic supplementation on GI symptoms and markers of GI permeability and damage during marathon training and racing. 24 runners took part in this double-blind, randomised trial. Participants took a probiotic supplement containing 25 billion organisms (Lactobacilli and bifidobacterial) or placebo for 4 weeks prior to the marathon race. Blood samples were taken before supplementation, pre and post marathon. Participants also completed a questionnaires regarding GI symptoms. All runners experienced GI symptoms during the marathon. Runners supplementing with probiotics reported fewer and less severe GI symptoms, both in training and during the race, and also showed increased performance during the race compared to the placebo group. There was no association between GI symptoms and markers of GI permeability and damage, although both were increased post-race in all participants. The authors conclude that athletes participating in endurance events, where GI symptoms are common and likely to affect performance, could consider probiotic supplementation in the weeks prior to competition.
Abstract
PURPOSE To evaluate the effects of probiotic supplementation on gastrointestinal (GI) symptoms, circulatory markers of GI permeability, damage, and markers of immune response during a marathon race. METHODS Twenty-four recreational runners were randomly assigned to either supplement with a probiotic (PRO) capsule [25 billion CFU Lactobacillus acidophilus (CUL60 and CUL21), Bifidobacterium bifidum (CUL20), and Bifidobacterium animalis subs p. Lactis (CUL34)] or placebo (PLC) for 28 days prior to a marathon race. GI symptoms were recorded during the supplement period and during the race. Serum lactulose:rhamnose ratio, and plasma intestinal-fatty acid binding protein, sCD14, and cytokines were measured pre- and post-races. RESULTS Prevalence of moderate GI symptoms reported were lower during the third and fourth weeks of the supplement period compared to the first and second weeks in PRO (p < 0.05) but not PLC (p > 0.05). During the marathon, GI symptom severity during the final third was significantly lower in PRO compared to PLC (p = 0.010). The lower symptom severity was associated with a significant difference in reduction of average speed from the first to the last third of the race between PLC (- 14.2 ± 5.8%) and PRO (- 7.9 ± 7.5%) (p = 0.04), although there was no difference in finish times between groups (p > 0.05). Circulatory measures increased to a similar extent between PRO and PLC (p > 0.05). CONCLUSION Probiotics supplementation was associated with a lower incidence and severity of GI symptoms in marathon runners, although the exact mechanisms are yet to be elucidated. Reducing GI symptoms during marathon running may help maintain running pace during the latter stages of racing.
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Dietary fructooligosaccharides affect intestinal barrier function in healthy men.
Ten Bruggencate, SJ, Bovee-Oudenhoven, IM, Lettink-Wissink, ML, Katan, MB, van der Meer, R
The Journal of nutrition. 2006;136(1):70-4
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Fructooligosaccharides (FOS) are nondigestible carbohydrates assumed beneficial because they stimulate the protective colonic microflora (bifidobacteria, lactobacilli) that produce organic acids that, in turn, increase host defence against invasive pathogens. However, studies show that FOS increases cytotoxicity of intestinal contents (fecal water), mucin excretion, and intestinal permeability in rats, reducing resistance to infection (since host defence depends on barrier function). This study aims to prove whether the adverse adverse effects of FOS that occurred before infection in rats would occur in humans. This is important because FOS has been added to a variety of products including dairy products and infant formulas. This is a double-blind, placebo-controlled crossover study design with 2 supplement periods of 2 wk. separated by 1 washout period of 2 wks. 34 healthy men were randomly divided in 2 groups. Subjects consumed either lemonade with 20g of FOS or 6g of sucrose (placebo) per day in 3 divided doses (morning, afternoon, and evening). They avoided dairy products and calcium rich foods (since FOS-induced adverse effects in rats is inhibited by calcium intake), foods high in fermentable nondigestible carbohydrates and pro- or prebiotics. Alcohol consumption was restricted. Habitual diet was otherwise maintained. The lemonade also contained the intestinal permeability marker chromium EDTA (CrEDTA). On the last 2 days of both supplement periods, quantitative food intake (self-reported) was measured, 24-h urine samples taken, and gastrointestinal symptoms rated (visual analogue scale). 24-h fecal samples were also collected. Dietary FOS consumption increased bifidobacteria, lactobacilli, lactic acid and decreased fecal pH. Cytotoxicity of fecal water and urinary and fecal CrEDTA excretion were not affected by FOS. Frequency of flatulence, bloating, abdominal pain and cramps were increased in the FOS period. The concept of stimulating endogenous microflora and intestinal organic acid production by rapid fermentation of nondigestible carbohydrates is beneficial for the intestinal barrier in humans is not supported.
Abstract
In contrast to most expectations, we showed previously that dietary fructooligosaccharides (FOS) stimulate intestinal colonization and translocation of invasive Salmonella enteritidis in rats. Even before infection, FOS increased the cytotoxicity of fecal water, mucin excretion, and intestinal permeability. In the present study, we tested whether FOS has these effects in humans. A double-blind, placebo-controlled, crossover study of 2 x 2 wk, with a washout period of 2 wk, was performed with 34 healthy men. Each day, subjects consumed lemonade containing either 20 g FOS or placebo and the intestinal permeability marker chromium EDTA (CrEDTA). On the last 2 d of each supplement period, subjects scored their gastrointestinal complaints on a visual analog scale and collected feces and urine for 24 h. Fecal lactic acid was measured using a colorimetric enzymatic kit. The cytotoxicity of fecal water was determined with an in vitro bioassay, fecal mucins were quantified fluorimetrically, and intestinal permeability was determined by measuring urinary CrEDTA excretion. In agreement with our animal studies, FOS fermentation increased fecal wet weight, bifidobacteria, lactobacilli, and lactic acid. Consumption of FOS increased flatulence and intestinal bloating. In addition, FOS consumption doubled fecal mucin excretion, indicating mucosal irritation. However, FOS did not affect the cytotoxicity of fecal water and intestinal permeability. The FOS-induced increase in mucin excretion in our human study suggests mucosal irritation in humans, but the overall effects are more moderate than those in rats.