The escalating global prevalence of obesity and its related metabolic disorders has spurred the search for effective and safe nutritional interventions. The connection between obesity and imbalances in the gut microbiota (dysbiosis) has led to the exploration of specific bacterial strains as potential probiotics for weight management and metabolic health improvement. Among these strains, Bifidobacterium animalis subsp. lactis B420 (B420) has been extensively studied for its impact on the gut microbiota, metabolic well-being, and mechanisms of action through various in vitro, pre-clinical, and clinical trials.
Understanding the Gut Microbiota and its Role in Metabolic Health
The gut microbiome plays a crucial role in regulating body weight and fat maintenance. The gastrointestinal tract harbors a vast number of bacteria (1013), which roughly equals the number of cells that make up the human body. Commensal gut bacteria are involved in many metabolic processes such as fermentation of undigested carbohydrates into short-chain fatty acids and other metabolites, digestion and absorption of nutrients, but also in the maturation of the immune system, as well as providing protection against incoming, potentially pathogenic microbes. Dysbiosis, an imbalance within the microbiome, is now recognized to have wide clinical impacts, with links established to a diverse set of adverse health conditions including obesity.
Bifidobacterium Lactis: A Key Player in Gut Health
Bifidobacteria were discovered at the turn of 18th and 19th centuries by Tissier in the feces of breast-fed infants, and since then, Bifidobacterium spp. have been shown to be comprised of Gram-positive, non-spore forming, anaerobic, pleomorphic bacteria. Bifidobacterium animalis subsp. lactis (B. lactis) is one of the most common Bifidobacterium species utilized as a probiotic in commercial products in North America and Europe. B. lactis has been used in fermented foods for decades and was scientifically classified by Meile et al. in 1997, then re-classified as B. animalis subsp. lactis in 2004.
B420: A Promising Probiotic for Metabolic Health
One of the probiotic strains that has been studied for its mechanism of action and clinical benefits is Bifidobacterium animalis subsp. lactis 420 (B420). Recently, the complete genome sequence of B420 has been published, allowing for more stringent strain identity confirmation among other genetically similar B. lactis strains. The health benefits that have been shown with B420 consumption include for example control of body fat mass gain in a human intervention trial. Preclinical data furthermore suggest enhancement of mucosal integrity and glycemic control, as well as improving host resistance to pathogens.
Impact on Gut Microbiota Composition
The effect of B420 on microbiota composition was studied as part of a placebo-controlled human intervention trial. The results indicated that B420 consumption modulated the gut microbiota-both alone, as well as in synbiotic product containing prebiotic fiber with probiotic-of an overweight study population towards the composition associated with a lean phenotype. B420 alone was shown to increase the relative levels of beneficial microbes, such as Lactobacillus spp. and Akkermansia spp. Furthermore, Bifidobacterium spp. was positively correlated with lean body mass, a finding that is in accordance with a previous publication reporting significantly less fat mass after B420 consumption compared to placebo.
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A synbiotic product consisting of B420 together with polydextrose (PDX, a water-soluble branched oligomer of glucose and sorbitol classified as dietary fiber) administered in a human clinical trial showed an increase of the relative proportion of Akkermansia spp., Christensenellaceae, and Methanobrevibacter spp. in the human fecal microbiota, while the prevalence of Paraprevotella spp. was reduced. Christensenellaceae positively correlated with the fecal branched chain fatty acids (BCFAs), which in previous studies have been indicated to inhibit de novo lipogenesis, thus potentially affecting lipid and glucose metabolism in human adipocytes. Further, in the synbiotic group where an increase in the prevalence of Christensenellaceae was seen, this negatively correlated with energy intake, waist-hip-ratio at baseline, waist-area body fat and cholesterol markers.
Effects on Body Weight and Fat Mass
Amar and colleagues demonstrated in mice that B420 supplementation was able to attenuate fat mass gain in obese and diabetic mice, concomitantly decreasing the translocation of commensal intestinal bacteria into blood and adipose tissue increased by high fat diet (HFD)-induced diabetes. In line with these results, it has also been shown in a post hoc factorial analysis of a randomized clinical study that B420 supplementation resulted in significantly less total body fat mass (−4%, p = 0.002 vs. non-B420 containing groups, per protocol (PP) population) and waist circumference (−2.4%, p = 0.004 vs. non-B420 containing groups, PP population). In addition, the effect seemed to be concentrated in the fat localized in the central region of the body and thus seen as favorable changes in trunk fat mass (p = 0.0002) and android fat mass (p = 0.004) in the PP population when compared to groups not consuming B420.
Combining B420 with other probiotics, or prebiotics-as synbiotic combination products-offers further possibilities regarding metabolic health. In the previously mentioned clinical trial, a synbiotic consisting of B420 with PDX was able to control body fat mass accumulation after a six month intervention with an average difference of 1.4 kg in total body fat mass (p = 0.02) between the synbiotic group and placebo group in the PP population. The difference in body fat mass was most evident in the trunk region where there was 6.7% less fat mass (p = 0.008) and a 2.7% (2.6 cm) smaller waist circumference (p = 0.047) in the synbiotic group compared to the placebo group at the end of the intervention. As trunk fat accumulation is associated with ectopic fat accumulation, controlling this inner organ fat is crucial for metabolic health.
Impact on Energy Intake and Satiety
Furthermore, in the human intervention trial, B420 significantly reduced energy intake by approximately 210 kcal/day (p = 0.037) compared to the non-B420 containing group. This finding was supported by the earlier in vitro findings, in which the expression of satiety marker peptide YY (PYY) was shown to be increased by B420. The role of the intestinal microbiota in host appetite and food intake has been suggested to be conveyed through both regulation of eating-related behavior, possibly via the microbiota gut-brain axis, as well as via directly acting on molecules regulating appetite and satiety. Therefore, some of the effects on metabolic health observed in clinical trials with B420 might be a result of changes in satiety and appetite hormone levels affecting food intake. However, this hypothesis requires further validation.
Potential Mechanisms of Action
Current research supports the hypothesis that gut dysbiosis leads to an imbalance in the inflammatory processes and loss of epithelial integrity. Bacterial components, like endotoxins, that leak out of the gut can invoke low-grade, chronic, and systemic inflammation. This imbalanced state is often referred to as metabolic endotoxemia. Scientific evidence indicates that B420 can slow down many of these detrimental processes via multiple signaling pathways, as supported by mechanistic in vitro and in vivo studies. The research further indicates that B420 may improve the epithelial integrity by rebalancing a dysbiotic state induced by an obesogenic diet, for example by increasing the prevalence of lean phenotype microbes such as Akkermansia muciniphila.
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B420 Alleviates Liver Injury in Experimental Autoimmune Hepatitis (EAH) Mice
In a study, B420 alleviated liver injury in EAH mice, partly by modulating gut microbiota and RIP3 signaling of liver macrophages, and these effects were accompanied by the increase of cecal SCFA production, upregulation of intestinal tight junction proteins, repression of liver pro-inflammatory cytokines and a decrease of Th17 cells in liver and spleen. Collectively, these findings revealed that probiotics supplement might exhibit potential efficacy against AIH through targeting gut-liver axis.
Safety and Technological Aspects of B420
The safety and technological aspects of B420 are crucial for delivering its health benefits. These include genomic characterization, antibiotic resistance profiling, stability in the product, and survival of the live probiotic in the intestine.
Safety
When taken by mouth: B. lactis is likely safe. It's been used safely alone and together with other probiotics for up to one month. Some people might experience gas and bloating from probiotics, but B. lactis seems to be well-tolerated.
Special Precautions and Warnings
When taken by mouth: B. lactis is likely safe. It's been used safely alone and together with other probiotics for up to one month. Some people might experience gas and bloating from probiotics, but B. lactis seems to be well-tolerated.
Pregnancy and breast-feeding: There isn't enough reliable information to know if B. lactis is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.
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Children: B. lactis likely safe for most children when taken by mouth for up to 8 months. It might cause diarrhea in some children. However, there isn't enough reliable information to know if B. lactis is safe for very small premature infants.
Weakened immune system: Some probiotics have caused blood infections in a small number of people with weakened immune systems. If you have a weakened immune system, talk with your healthcare provider before taking B. lactis.
Interactions
Moderate Interaction Be cautious with this combination B. lactis is a type of friendly bacteria. Antibiotics are used to reduce harmful bacteria in the body. Taking antibiotics along with B. lactis might reduce the effects of B. lactis. To avoid this interaction, take B. lactis products at least two hours before or after antibiotics.
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