Bacteroides-Prevotella group

The Bacteroides-Prevotella group encompasses two significant genera within the Bacteroidetes phylum, playing crucial roles in the human gut microbiome. 

Originally classified together, Bacteroides and Prevotella were separated in 1990 due to their distinct characteristics. 

‍Bacteroides is more prevalent in industrialized populations with Western diets high in animal protein and saturated fats, while Prevotella is commonly found in non-Western populations consuming plant-rich diets. 

These bacteria exhibit a unique antagonistic relationship, with one typically dominating over the other in an individual's gut. 

They are involved in breaking down complex carbohydrates, producing short-chain fatty acids, and influencing immune responses and nutrient metabolism. 

The balance between these genera, often assessed by the Prevotella-to-Bacteroides (P/B) ratio, is crucial for gut health, influencing metabolic functions and potentially playing a role in various diseases. 

Despite their beneficial roles, imbalances in their levels can lead to adverse health effects, highlighting the importance of understanding their interactions and impacts on the human microbiome.

What is the Bacteroides-Prevotella Group? [3., 12.] 

Bacteroides and Prevotella are two significant genera within the phylum Bacteroidetes that play crucial roles in the human gut microbiome. 

Although historically part of the same genus, they were separated in 1990. 

Both are Gram-negative, anaerobic bacteria known for their high adaptability to various environmental conditions and diets, as well as their ability to utilize complex polysaccharides and mucins. 

Their distribution in human populations differs notably: Bacteroides is more common in industrialized populations with Western diets, while Prevotella is more prevalent in non-Westernized populations with plant-rich diets. [3., 17., 20.] 

This distribution reflects their dietary associations, with Bacteroides linked to diets high in animal protein and saturated fats, and Prevotella associated with diets rich in complex carbohydrates, fruits, and vegetables. [17., 20.] 

These genera tend to have an antagonistic relationship in the gut microbiome, with one usually dominating over the other in an individual's gut. 

Both genera are involved in important metabolic functions, including breaking down complex carbohydrates, producing short-chain fatty acids and other metabolites, and participating in vitamin synthesis and protein metabolism. 

Their impact on human health can be both beneficial and potentially harmful, depending on the context, and they significantly influence overall gut microbiome composition and function. 

These taxa are often analyzed based on their relative abundance and ratio to each other, known as the Prevotella-to-Bacteroides (P/B) ratio.

What is Bacteroides? [1., 7., 8., 15., 19., 20., 21.] 

Bacteroides spp. are essential members of the human gut microbiota, playing a crucial role in maintaining gut homeostasis. 

Along with Prevotella and Porphyromonas, they belong to the Bacteroidetes phylum. 

The proportion of Bacteroidetes varies by population, geography, age, and diet. 

Bacteroides spp. are gram-negative, non-spore forming, anaerobic, rod-shaped bacteria, with approximately 24 identified species. Among these, Bacteroides fragilis and Bacteroides thetaiotaomicron are the most studied. 

These bacteria thrive in anaerobic conditions, utilizing complex polysaccharides for energy through fermentation, and are efficient in degrading dietary fibers and carbohydrates, producing short-chain fatty acids (SCFAs) and other metabolites that impact host physiology.

Bacteroides spp. use a Type VI secretion system (T4SS) to release toxins targeting other bacteria, maintaining a competitive advantage and stabilizing the gut ecosystem. They are key contributors to the microbial community in the colon, influencing immune responses, nutrient metabolism, and intestinal barrier function. 

Primarily found in the distal gut, they ferment indigestible polysaccharides, producing SCFAs crucial for gut health, glucose homeostasis, and lipid metabolism. 

Bacteroides adapt flexibly to the gut's nutritional environment, utilizing a wide range of dietary polysaccharides and proteins, aided by numerous carbohydrate-active enzymes (CAZYmes).

Diet significantly affects Bacteroidetes levels. Traditional diets high in fiber and complex carbohydrates are associated with a higher prevalence of Bacteroides, contributing to better metabolic health. [18.] 

Conversely, modern diets high in animal products, processed and high-fat foods may reduce Bacteroides levels, potentially impacting gut homeostasis and overall health. [18.] 

Overnutrition decreases Bacteroidetes, affecting energy harvest efficiency, while undernutrition and fasting can either increase or deplete Bacteroidetes levels, depending on the conditions. 

Studies show varied associations between Bacteroidetes and type 2 diabetes, with specific species affecting host metabolism differently. 

Although some studies show a healthy amount of Bacteroides is beneficial for metabolic health, the effects on glucose metabolism can vary significantly depending on dietary context and relative levels of Bacteroides subspecies. [7.] 

Imbalances in gut microbiota, including alterations in Bacteroides spp. abundance, are linked to numerous diseases. 

Bacteroides have shown potential in preventing and treating non-alcoholic fatty liver disease (NAFLD) by modulating gut health, reducing liver inflammation, mitigating hepatic steatosis, and enhancing intestinal barrier function. 

Overall, modulating Bacteroides metabolism through dietary interventions holds potential for restoring gut microbiota balance and promoting metabolic health.

What is Prevotella? [17.] 

Prevotella is a diverse genus of Gram-negative anaerobic bacteria, first described in 1990 by Shar and Collins. 

The genus includes oral species with saccharolytic capabilities and bile salt sensitivity, previously classified under Bacteroides. 

Prevotella species are non-spore-forming, non-motile short rods, mostly saccharolytic, and part of the family Prevotellaceae, which also includes Paraprevotella, Alloprevotella, and Hallella.

Prevotella spp. are found in various animal hosts and free-living environments. They are common in mammal-associated microbiomes, inhabiting human skin, oral cavity, vagina, and gastrointestinal tract. 

Prevotella dominance is notable in non-Westernized populations with traditional diets, while Westernized populations see a decreased prevalence of Prevotella, often replaced by Bacteroides species. This suggests that modern lifestyles contribute to the loss of Prevotella diversity, with potential health consequences. [17.] 

Prevotella contains more than 50 characterized species, primarily associated with humans. They play significant roles in the microbiome balance between health and disease, influenced by diet, lifestyle, and geography. 

Although their exact role in health and disease is unclear, they are implicated in inflammatory autoimmune diseases, bacterial vaginosis, and oral biofilm formation. [17.] 

There are conflicting reports on whether Prevotella spp. are beneficial or detrimental to health, especially in glucose homeostasis. [17.] 

Prevotella spp. exhibit extensive diversity and are found in various human body sites. They are particularly prevalent in non-Westernized populations and non-Western diets rich in carbohydrates and fiber, suggesting a diet and lifestyle influence. [17.] 

Age and sex also affect their distribution, with some species more prevalent in elderly individuals and others linked to female hormone metabolism. [17.] 

‍Prevotella spp. are essential in microbial ecology, especially in the gut, where they help digest complex polysaccharides. Studies suggest a link between Prevotella and improved glucose metabolism and weight loss with fiber-rich diets, although some studies associate Prevotella with insulin resistance. [17.] 

Prevotella's role as potential pathogens includes associations with oral infections, autoimmune diseases, and systemic infections. However, their pathogenic potential is mainly opportunistic. 

Antibiotic resistance in Prevotella is a growing concern, particularly resistance to β-lactam antibiotics and metronidazole. [17.] 

Overall, Prevotella spp. are key players in the human microbiome, with significant implications for health and disease. Further research is needed to understand their ecological roles, interactions with the human host, and impact on health, particularly in the context of dietary and lifestyle changes associated with Westernization.

Health Implications Associated with the Bacteroides-Prevotella Group

The Bacteroides-Prevotella Group in Colorectal Cancer (CRC) [16.]

The gut microbiome plays a crucial role in the development and progression of colorectal cancer (CRC). 

Significant dysbiosis has been noted in the gut microbiota composition in colorectal cancer (CRC) patients compared to individuals with normal colonoscopies. [16.]

Analyzing stool samples from 60 CRC patients and 119 controls using pyrosequencing and qPCR, they found that the Bacteroides/Prevotella group was significantly higher in CRC patients. [16.]

This elevation correlated with increased IL17-producing cells in the mucosa, suggesting a link between microbial imbalance and mucosal immune responses. 

The Bacteroides/Prevotella ratio might serve as a potential marker for CRC and emphasizes the importance of gut microbiota in colorectal cancer pathophysiology.

Bacteroides-Prevotella Group and Weight Management [4.]

The ratio of Prevotella to Bacteroides (P/B) in the gut microbiota can predict weight loss success on different diets. 

Over 24 weeks, participants with a high P/B ratio lost significantly more body weight and fat, especially on a high-fiber diet, compared to those with a low P/B ratio. [4.] 

This suggests that individuals with a higher P/B ratio respond better to fiber-rich diets, highlighting the potential of using gut microbiota composition to personalize weight loss strategies. 

One study confirms that a high P/B ratio is associated with greater susceptibility to diet-induced weight loss, emphasizing the importance of dietary fiber in managing body weight. [4.] 

Bacteroides-Prevotella Group and Type 2 Diabetes [11.]

Recent research highlights the critical role of gut dysbiosis in obesity and type 2 diabetes (T2D), emphasizing how shifts in gut microbial diversity and abundance of pathogenic bacteria can disrupt metabolic homeostasis, worsen triglyceride and cholesterol levels, and instigate chronic inflammation. [11.] 

This dysbiosis impacts the gut-brain axis, leading to insulin resistance, and also influences visceral adipose tissue function in obese individuals with T2D. 

A particular focus is on the Bacteroides and Prevotella groups. An increased ratio of Prevotella to Bacteroides has been associated with diets high in carbohydrates and fibers and linked to improved glucose homeostasis and weight management. 

Conversely, shifts favoring Bacteroides over Prevotella are often observed in high-fat diets and linked to metabolic disturbances.

The complex interaction between diet, gut microbiota, and microbial metabolites plays a significant role in T2D pathogenesis. Gut-derived metabolites such as short-chain fatty acids (SCFAs) and bile acids can influence lipid metabolism, inflammation, and insulin sensitivity. 

Specific microbial alterations, including an increase in Firmicutes and a reduction in Bacteroidetes, to which Prevotella and Bacteroides belong, have been associated with obesity and its metabolic complications. [11.] 

Therapeutic strategies targeting gut microbiota, such as probiotics, prebiotics, and fecal microbial transplantation, show promise in managing T2D by modulating the gut microbiome, improving gut barrier function, and reducing systemic inflammation. [11.] 

Bacteroides-Prevotella Group and Sarcopenia [9.]

The gut microbiome significantly influences sarcopenia, a condition characterized by muscle mass loss and functional decline. [9.] 

One study showed that non-sarcopenia participants had enriched branched-chain amino acid (BCAA) metabolism, with lower levels of BCAA-related metabolites in sarcopenia patients. [9.] 

In a mouse model, gavaging with live P. copri (LPC) resulted in higher blood BCAA levels, improved muscle function, and increased muscle mass. 

These findings suggest that P. copri can mitigate muscle mass and function decline, indicating its therapeutic potential for managing sarcopenia. 

Research highlights the gut-muscle axis's crucial role, mediated by the gut microbiome, in muscle health.

Overall, targeting the gut microbiota, particularly through enhancing levels of P. copri and BCAA, could be an effective strategy for treating sarcopenia.

Laboratory Testing for Bacteroides-Prevotella Group

Test Information, Sample Collection and Preparation

Bacteroides-Prevotella Group levels are assessed in stool samples.  Stool samples may be collected from the comfort of home.  

Testing may require avoidance of certain medications and/or supplements including probiotics prior to sample collection.  It is important to consult with the ordering provider for full test preparation instructions.  

Interpretation of Test Results

Optimal Levels of Bacteroides-Prevotella Group

It is important to consult with the laboratory company used for test interpretation. 

One lab company provides the following reference range for Bacteroides spp. levels alongside Prevotella spp., and reports this on a scale from -3 (low prevalence of these organisms) to +3 (high prevalence of these organisms).  [13.]

Another company provides the following range for the Bacteroides-Prevotella Group: 3.4E6  - 1.5E9 CFU/g stool. [14.] 

Optimal levels are recommended to fall within this range, as excessively high or low levels may be associated with health conditions.

Clinical Significance of Elevated Bacteroides-Prevotella Group

An elevated Bacteroides-Prevotella group indicates an increased presence of these organisms in an individual’s microbiome.  

The clinical significance of an elevated Bacteroides-Prevotella group is multifaceted and closely tied to dietary patterns and metabolic functions. 

This group is generally associated with a Western diet high in animal protein and saturated fats, with a Bacteroides-dominated microbiome positively correlated with long-term consumption of such diets. Metabolically, these bacteria play important roles. 

Elevated levels of Bacteroides-Prevotella are associated with reduced bacterial gene richness in the gut microbiome, potentially impacting overall microbial diversity. [6.] Altered levels may also have clinical implications regarding metabolic health and weight management.  

While these bacteria are normally part of the gut microbiota, they can become opportunistic pathogens under certain conditions. Bacteroides species, in particular, are significant clinical pathogens present in most anaerobic infections and can be associated with mortality. [2.] 

Clinical Significance of Decreased Levels of Bacteroides-Prevotella Group

As members of the Bacteroidetes phylum, decreased levels of Bacteroides-Prevotella signify a decrease in Bacteroidetes levels.  

When assessing overall microbial balance, the Bacteroidetes/Firmicutes ratio holds clinical significance, as a decreased Bacteroidetes/Firmicutes ratio has been associated with poorer metabolic health and increased weight gain. 

Several studies have found an association between high Bacteroidetes levels and a lean phenotype or healthy weight.  A higher Bacteroidetes/Firmicutes ratio was associated with a lower body mass index (BMI). [7., 10.]

Natural Ways to Optimize Microbiome Health [5.] 

A healthy diet and lifestyle are foundational for microbiome health.  

Diet and Nutrition

• Consume Diverse Foods: increase the variety of fruits, vegetables, whole grains, nuts, seeds, and legumes to promote microbial diversity.

• High-Fiber Diet: focus on fiber-rich foods to support the growth of beneficial bacteria.

• Fermented Foods: include yogurt, kefir, sauerkraut, kimchi, and other fermented foods to introduce probiotics.

• Polyphenol-Rich Foods: consume foods high in polyphenols such as berries, green tea, dark chocolate, and red wine to stimulate beneficial bacteria growth.

• Prebiotics: incorporate prebiotic-rich foods like garlic, onions, asparagus, and bananas to nourish beneficial bacteria.

Lifestyle

• Regular Exercise: engage in consistent physical activity to enhance gut microbiota diversity and composition.

• Stress Management: practice stress-reducing activities such as yoga, meditation, and mindfulness to prevent microbiota dysbiosis.

Medications and Supplements

• Probiotics: consider probiotic supplements to increase beneficial bacteria in the gut.

• Avoid Unnecessary Antibiotics: use antibiotics only when necessary to avoid disrupting the gut microbiome.

Environmental Factors

• Limit Artificial Sweeteners: avoid artificial sweeteners that can negatively affect gut microbiota.

• Healthy Sleep Patterns: maintain regular sleep patterns to support a balanced gut microbiome.

Hygiene Practices

• Avoid Over-Sanitization: limit the use of antibacterial soaps and sanitizers to maintain a healthy microbiota balance.

FAQ: Understanding the Bacteroides-Prevotella Group

The Bacteroides-Prevotella group comprises two prominent genera of bacteria that play significant roles in the human gut microbiome. This FAQ section addresses common questions about the Bacteroides-Prevotella group, their functions, and their impact on health.

What Is the Bacteroides-Prevotella Group?

The Bacteroides-Prevotella group includes two genera of Gram-negative, anaerobic bacteria: Bacteroides and Prevotella. These bacteria are prevalent in the human gut microbiome and are essential for the digestion of complex carbohydrates and maintaining gut health.

What Roles Do Bacteroides and Prevotella Play in the Gut Microbiome?

Bacteroides and Prevotella bacteria help break down complex carbohydrates, producing short-chain fatty acids and other metabolites that support gut health. 

Bacteroides are more involved in the digestion of proteins and animal fats, while Prevotella is associated with the breakdown of plant-based fibers and carbohydrates.

How Are Bacteroides and Prevotella Detected?

Bacteroides and Prevotella can be detected using microbiological and molecular techniques such as stool culture, 16S rRNA gene sequencing, and metagenomic analysis. These methods allow for the identification and quantification of these bacteria in the gut microbiome.

What Are the Benefits of Bacteroides and Prevotella?

The benefits of Bacteroides and Prevotella include:

• Aiding in the digestion of complex carbohydrates and fibers

• Producing beneficial short-chain fatty acids

• Supporting the gut barrier function

• Helping to maintain a balanced gut microbiome

• Modulating the immune system

Can Bacteroides and Prevotella Be Harmful?

While Bacteroides and Prevotella are generally beneficial, an imbalance in the gut microbiome (dysbiosis) can lead to overgrowth of these bacteria, potentially contributing to gastrointestinal disorders such as irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and other metabolic conditions.

How Do Bacteroides and Prevotella Interact With Each Other and Other Gut Bacteria?

Bacteroides and Prevotella interact with each other and other gut bacteria through competitive and cooperative relationships. These interactions help maintain a balanced gut microbiome, where beneficial bacteria support each other's growth and function while keeping pathogenic bacteria in check.

How Can I Support a Healthy Balance of Bacteroides and Prevotella in My Gut?

Supporting a healthy balance of Bacteroides and Prevotella involves:

• Eating a balanced diet rich in dietary fiber, particularly from fruits, vegetables, and whole grains

• Consuming fermented foods such as yogurt, kefir, and sauerkraut

• Avoiding excessive use of antibiotics, which can disrupt the gut microbiome

• Maintaining a healthy lifestyle with regular exercise and stress management

When Should I Consult a Healthcare Provider About My Gut Microbiome?

You should consult a healthcare provider if you experience persistent digestive issues such as abdominal pain, bloating, diarrhea, or constipation. A healthcare provider can evaluate your symptoms, potentially recommend microbiome testing, and suggest appropriate treatments or dietary changes to improve gut health.

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