Bifidobacterium (genus) Benefits Explained

Bifidobacterium (Genus) Benefits Explained A Deep Dive into Probiotic Power

The human gut microbiome is a complex ecosystem teeming with trillions of microorganisms, playing a pivotal role in our health and well-being. Among the most important residents of this inner world is the Bifidobacterium genus. These beneficial bacteria are anaerobic or microaerophilic, gram-positive bacteria that are non-motile and non-spore-forming. Found predominantly in the gastrointestinal tract, but also present in other niches like the mouth, vagina, and even breast milk, Bifidobacterium species are considered cornerstone members of a healthy microbiome, particularly abundant in infants. As our understanding of the microbiome has grown, so too has the interest in modulating its composition for health benefits. Probiotic supplements, which introduce live beneficial bacteria into the gut, have become increasingly popular. Bifidobacterium-containing probiotics are among the most widely researched and consumed, lauded for their potential to support digestive health, boost immunity, influence mood, and offer a range of other systemic benefits. This exhaustive article delves deep into the known benefits of the Bifidobacterium genus as a dietary supplement, exploring the mechanisms behind their actions and offering a comprehensive look at their impact on human health.

Exploring the Bifidobacterium Genus Species and Significance

The Bifidobacterium genus comprises numerous species, each with potentially distinct characteristics and health effects. While the genus as a whole is recognized for its benefits, it’s crucial to understand that probiotic effects are often species-specific and even strain-specific. This means the benefits observed for Bifidobacterium longum may differ from those of Bifidobacterium breve or Bifidobacterium animalis. Some of the most commonly studied and utilized species in probiotic supplements include

• Bifidobacterium longum: Often found in adult and infant guts, linked to immune modulation and digestive health.
• Bifidobacterium breve: Prominent in infant guts, associated with digestion of complex carbohydrates and immune development.
• Bifidobacterium infantis: Particularly abundant in breastfed infants, known for its ability to utilize human milk oligosaccharides (HMOs) and significant anti-inflammatory properties.
• Bifidobacterium bifidum: Found throughout life, contributes to gut barrier function and immune responses.
• Bifidobacterium animalis (often subspecies lactis): A robust species commonly used in dairy products and supplements, recognized for its resilience and benefits for digestion and immunity.
• Bifidobacterium adolescentis: More common in adolescent and adult guts, involved in carbohydrate metabolism. The significance of Bifidobacterium stems from several factors

1. Early Colonizers: They are among the first bacteria to colonize the infant gut, playing a critical role in shaping the developing immune system and metabolism.
2. Abundance: In a healthy state, especially in infancy, they can constitute a large proportion of the total gut bacteria.
3. Metabolic Capabilities: They are highly efficient at fermenting complex carbohydrates (prebiotics) that humans cannot digest, producing beneficial metabolites.
4. Interaction with Host: They have extensive interactions with the gut lining and immune cells, influencing local and systemic health. Understanding these foundational aspects is key to appreciating the diverse and profound impacts Bifidobacterium probiotics can have.

How Bifidobacterium Works Mechanisms Behind Probiotic Benefits

The benefits attributed to Bifidobacterium are not magical; they are the result of specific, well-researched mechanisms of action within the host’s body, primarily within the gut ecosystem. Going deeper than simply listing benefits requires understanding how these bacteria exert their effects.

1. Fermentation of Non-Digestible Carbohydrates (Prebiotics): This is arguably the most significant mechanism. Bifidobacterium species are expert fermenters of dietary fibers, resistant starches, and oligosaccharides (like FOS, GOS, and HMOs). This fermentation process yields Short-Chain Fatty Acids (SCFAs), primarily acetate and lactate. While butyrate is the preferred energy source for colonocytes and has significant anti-inflammatory effects, Bifidobacterium produces acetate and lactate. Other gut bacteria, like certain clostridia and Faecalibacterium prausnitzii, can then convert lactate and acetate into butyrate. Thus, Bifidobacterium acts as a crucial partner in the SCFA production pipeline. SCFAs provide energy to colon cells, lower gut pH (inhibiting pathogens), enhance mineral absorption, and have widespread systemic effects, including immune modulation and appetite regulation.
2. Lowering Intestinal pH: The production of organic acids (acetate, lactate) lowers the pH of the intestinal lumen. This acidic environment is unfavorable for many pathogens and opportunistic bacteria, helping to maintain a healthy microbial balance.
3. Competition with Pathogens: Bifidobacterium competes with harmful bacteria for adhesion sites on the intestinal epithelium and for available nutrients. By occupying these niches and consuming resources, they make it harder for pathogens to establish colonies.
4. Production of Antimicrobial Substances: Some Bifidobacterium strains produce bacteriocins (proteins that kill or inhibit the growth of related bacterial species) and other antimicrobial compounds that directly target pathogens.
5. Strengthening the Gut Barrier Function: The intestinal epithelium acts as a critical barrier preventing harmful substances (toxins, pathogens, undigested food particles) from entering the bloodstream. Bifidobacterium can enhance this barrier function

• Increasing the expression and assembly of tight junction proteins (like occludin, claudins, ZO-1) that seal the gaps between intestinal cells.
• Stimulating mucin production, which forms a protective layer over the epithelium.
• Reducing inflammation that could otherwise compromise barrier integrity (leaky gut).

6. Modulation of the Immune System: The gut is the largest immune organ, and Bifidobacterium interacts extensively with gut-associated lymphoid tissue (GALT). Their mechanisms include

• Interacting with immune cells like dendritic cells and macrophages.
• Influencing cytokine production (reducing pro-inflammatory cytokines like TNF-α and IL-6, while potentially increasing anti-inflammatory ones like IL-10).
• Promoting the development of regulatory T cells (Tregs), which help maintain immune tolerance and prevent excessive inflammation.
• Enhancing IgA production, an antibody crucial for neutralizing pathogens and toxins in the gut lumen.

7. Production of Vitamins: Certain Bifidobacterium species can synthesize B vitamins (like folate, biotin, riboflavin) and vitamin K, contributing to host nutrition.
8. Detoxification: Some strains may help detoxify harmful compounds, including certain carcinogens and heavy metals, by binding to them or enzymatic breakdown.
9. Modulation of the Gut-Brain Axis: Bifidobacterium can influence brain function and mood through various pathways

• SCFA production (acetate can cross the blood-brain barrier).
• Modulating neurotransmitter production or precursors (e.g, influencing serotonin and GABA pathways).
• Reducing systemic inflammation, which is linked to mood disorders.
• Affecting vagal nerve signaling. These mechanisms work synergistically, explaining the broad spectrum of health benefits associated with adequate levels and supplementation of Bifidobacterium.

Bifidobacterium for Digestive Wellness IBS, IBD, Constipation & More

The most well-established benefits of Bifidobacterium probiotics are centered around improving digestive health. Their role in maintaining a balanced gut ecosystem, producing beneficial metabolites, and strengthening the gut barrier makes them invaluable for managing various gastrointestinal conditions.

• Irritable Bowel Syndrome (IBS): IBS is a functional gut disorder characterized by symptoms like abdominal pain, bloating, gas, constipation, and diarrhea. Dysbiosis (an imbalance in gut microbes) is often implicated. Numerous studies have shown that specific Bifidobacterium strains can significantly alleviate IBS symptoms. Bifidobacterium longum NCC3001 (also known as B. longum 1714) has shown promise in reducing depression and improving quality of life in IBS patients. Bifidobacterium infantis 35624 (now often classified as B. longum subsp. infantis) has demonstrated efficacy in reducing overall IBS symptoms, including pain, bloating, and bowel habit satisfaction. The mechanisms include reducing visceral hypersensitivity (pain), modulating gut motility, reducing inflammation, and influencing the gut-brain axis to alleviate associated anxiety and depression.
• Inflammatory Bowel Disease (IBD): Conditions like Ulcerative Colitis (UC) and Crohn’s Disease (CD) are characterized by chronic gut inflammation. While probiotics are not a cure for IBD, certain Bifidobacterium strains, often used in multi-species formulations, may help manage symptoms and maintain remission. They can contribute by strengthening the gut barrier, reducing pro-inflammatory cytokines, increasing anti-inflammatory signals (like IL-10), and restoring a healthier microbial balance. However, results are mixed, and probiotics are typically used as an adjunct therapy under medical supervision.
• Constipation: Certain Bifidobacterium species, such as Bifidobacterium animalis subsp. lactis (e.g, strain DN-173 010 or BB-12), have been shown to improve gut transit time and increase stool frequency and consistency, particularly in individuals with chronic constipation. This is likely mediated by SCFA production, which can stimulate gut motility, and by helping to restore a more favorable microbial environment.
• Diarrhea: Bifidobacterium probiotics can be helpful in managing various types of diarrhea.
• Antibiotic-Associated Diarrhea (AAD): Antibiotics disrupt the natural gut flora, often leading to diarrhea. Supplementing with Bifidobacterium (often in combination with Lactobacillus) can help restore microbial balance, reduce pathogen overgrowth (like C. difficile), and prevent or reduce the severity of AAD. Bifidobacterium lactis is a commonly used species for this purpose.
• Infectious Diarrhea: While less potent than for AAD, some Bifidobacterium strains may help reduce the duration or severity of acute infectious diarrhea by competing with pathogens and supporting immune responses.
• Lactose Intolerance: Individuals with lactose intolerance lack sufficient lactase enzyme to break down lactose sugar. Some Bifidobacterium species, particularly Bifidobacterium animalis subsp. lactis, possess beta-galactosidase activity, the enzyme needed to digest lactose. While the effect varies, consuming Bifidobacterium-fortified dairy products or supplements with meals containing lactose may help alleviate symptoms like bloating, gas, and diarrhea.
• General Gut Comfort and Regularity: Even in individuals without diagnosed conditions, Bifidobacterium supplementation can contribute to a healthier, more comfortable digestive system by supporting balanced flora, reducing bloating and gas, and promoting regular bowel movements. The effectiveness is highly dependent on the specific species and strain used, the dosage, and the individual’s baseline gut health.

Boosting Immunity with Bifidobacterium Allergies, Infections, and Autoimmunity

The profound interaction between the gut microbiome and the immune system makes Bifidobacterium a key player in immune modulation. As early colonizers, they are critical in “educating” the developing immune system in infants. Throughout life, they continue to influence immune responses, offering protection against pathogens and potentially modulating allergic and autoimmune conditions.

• Enhancing Immune Responses: Bifidobacterium interacts directly and indirectly with immune cells in the gut lining. They can stimulate the production of immune signaling molecules (cytokines) that promote a balanced immune response. They also enhance the production of secretory IgA, an antibody that coats the gut lining and helps neutralize pathogens and toxins before they can cause harm. SCFA production also plays an immune-modulatory role, influencing immune cell function both locally and systemically.
• Reducing Susceptibility to Infections: By strengthening the gut barrier, competing with pathogens, producing antimicrobial substances, and enhancing immune surveillance, Bifidobacterium can reduce the risk and severity of various infections, particularly respiratory and gastrointestinal ones. Studies, especially in children and the elderly, have shown that supplementation can decrease the incidence and duration of common colds and other respiratory tract infections.
• Modulating Allergic Responses: The “hygiene hypothesis” suggests that reduced exposure to microbes in early life contributes to the rise in allergic diseases. Bifidobacterium, particularly Bifidobacterium infantis and Bifidobacterium breve, present early in life, are thought to play a crucial role in guiding the immune system towards tolerance rather than hypersensitivity. Supplementation, especially during pregnancy and early infancy, has been researched for its potential to reduce the risk of developing allergic conditions like eczema and food allergies in high-risk infants. The mechanisms involve promoting Th1 responses over Th2 (allergic) responses, increasing regulatory T cells, and strengthening the gut barrier to prevent allergen entry.
• Influencing Autoimmunity: While research is still evolving, there is growing interest in the role of the microbiome in autoimmune diseases. By modulating immune responses, reducing systemic inflammation, and improving gut barrier function, Bifidobacterium may play a supportive role in managing or potentially reducing the risk of certain autoimmune conditions, although this area requires much more research. The immune benefits are complex and depend heavily on the specific strain and the host’s immune status and genetic predisposition.

The Gut-Brain Connection Bifidobacterium’s Impact on Mental Health and Mood

The bidirectional communication highway between the gut and the brain, known as the gut-brain axis, is a rapidly expanding area of research. The gut microbiome is a key modulator of this axis, influencing neurological function, behavior, and mood. Bifidobacterium species have emerged as important “psychobiotics,” microbes that can exert positive effects on mental health.

• Anxiety and Depression: Dysbiosis and gut inflammation are often linked to mood disorders. Bifidobacterium can influence the gut-brain axis through several pathways
• SCFA Production: SCFAs, particularly butyrate (produced indirectly), can cross the blood-brain barrier and influence brain function. Acetate can also impact appetite regulation pathways in the brain.
• Neurotransmitter Modulation: Gut microbes can produce or influence the precursors of neurotransmitters like serotonin (a key mood regulator, 90% produced in the gut) and Gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter linked to anxiety. Some Bifidobacterium strains can produce GABA.
• Reducing Inflammation: Systemic inflammation is strongly associated with depression and anxiety. By reducing gut inflammation and improving barrier function, Bifidobacterium can lower the inflammatory load on the body and brain.
• Vagal Nerve Signaling: The vagus nerve is a major communication pathway between the gut and the brain. Microbes can influence vagal nerve activity.
• Stress Hormone Modulation: Some studies suggest certain probiotics can influence the hypothalamic-pituitary-adrenal (HPA) axis, the body’s central stress response system, potentially lowering levels of stress hormones like cortisol.
• Specific strains like Bifidobacterium longum 1714 have shown promising results in clinical trials, reducing self-reported stress, anxiety, and improving cognitive function in healthy volunteers.
• Stress Response: By modulating the HPA axis and potentially influencing neurotransmitter levels, Bifidobacterium may help the body cope better with stress.
• Cognitive Function: Emerging research suggests a link between gut health, Bifidobacterium levels, and cognitive performance. While more studies are needed, the anti-inflammatory effects, SCFA production, and influence on neurotransmitters could potentially support cognitive health and protect against age-related cognitive decline. The gut-brain axis is complex, and while promising, research into psychobiotics is still relatively young. However, the potential for Bifidobacterium to positively impact mental health is significant.

Metabolic Advantages Bifidobacterium and Weight, Blood Sugar, Cholesterol

Beyond the gut and brain, Bifidobacterium can influence systemic metabolic health, impacting weight management, blood sugar control, and lipid profiles. These effects are often mediated through their influence on SCFA production, inflammation, and modulation of host metabolism.

• Weight Management: While not a magic bullet for weight loss, Bifidobacterium may play a supportive role. SCFAs, particularly acetate and propionate (which can be produced from lactate/acetate), can influence satiety signals and energy expenditure. A healthier gut microbiome with sufficient Bifidobacterium may be more efficient at extracting energy from food and influencing fat storage signals. Dysbiosis, often characterized by lower levels of beneficial bacteria like Bifidobacterium, is frequently observed in individuals with obesity.
• Blood Sugar Control: Bifidobacterium can improve insulin sensitivity and glucose metabolism. Mechanisms include
• SCFA production Butyrate has been shown to improve insulin sensitivity in various tissues.
• Reducing Inflammation Chronic low-grade inflammation is a hallmark of insulin resistance and type 2 diabetes. By reducing inflammation, Bifidobacterium can help improve metabolic function.
• Improving Gut Barrier Function A leaky gut can allow bacterial products (like LPS) to enter the bloodstream, triggering inflammation and contributing to insulin resistance. Bifidobacterium helps maintain gut barrier integrity. Studies have shown that supplementation with certain Bifidobacterium strains can improve glucose tolerance and insulin sensitivity markers, particularly in individuals with metabolic syndrome or type 2 diabetes.
• Cholesterol Levels: Some Bifidobacterium species may help modulate cholesterol levels. Possible mechanisms include
• Deconjugation of bile salts Certain strains produce enzymes that deconjugate bile salts in the gut, which may lead to increased excretion of bile acids and require the liver to use more cholesterol to synthesize new ones, thus potentially lowering blood cholesterol.
• SCFA production Propionate, derived from fermentation, may inhibit cholesterol synthesis in the liver. While the effects on cholesterol are generally modest compared to dietary or pharmaceutical interventions, they represent another facet of Bifidobacterium’s systemic metabolic influence. These metabolic benefits highlight how gut health is intimately connected to broader physiological processes.

Bifidobacterium for Women’s Health Vaginal Balance and Pregnancy

The benefits of Bifidobacterium extend to women’s specific health needs, particularly concerning vaginal health and supporting a healthy pregnancy.

• Vaginal Health: The vaginal microbiome is distinct from the gut but can be influenced by it (the “gut-vaginal axis”). A healthy vaginal microbiome is typically dominated by Lactobacillus species, which produce lactic acid, maintaining a low pH that inhibits the growth of pathogens responsible for conditions like Bacterial Vaginosis (BV) and yeast infections. However, Bifidobacterium are also present in the healthy vaginal microbiome and can contribute to its stability. Supplementation with certain Bifidobacterium strains, sometimes in combination with Lactobacillus, has been explored for its potential to help prevent or treat recurrent BV and yeast infections by helping to restore a balanced microbial environment.
• Pregnancy and Infant Health: The maternal microbiome plays a crucial role in seeding the infant’s microbiome during birth and through breastfeeding. A healthy maternal Bifidobacterium population is important for the infant’s initial colonization. Supplementation during pregnancy may influence the maternal and potentially the infant microbiome, which in turn could impact the infant’s immune development and potentially reduce the risk of allergies and other immune-related conditions later in life. Bifidobacterium infantis, in particular, is vital for processing HMOs in breast milk, which are prebiotics specifically designed to nourish infant Bifidobacterium. Supporting a healthy Bifidobacterium population is therefore relevant for women across different life stages.

Beyond the Gut Skin, Oral, Bone Health Benefits of Bifidobacterium

The systemic effects of Bifidobacterium through immune modulation, SCFA production, and inflammation reduction suggest potential benefits in areas seemingly unrelated to the gut.

• Skin Health: The gut-skin axis describes the link between gut health and skin conditions. Dysbiosis and gut inflammation can contribute to inflammatory skin conditions like acne, eczema (atopic dermatitis), and psoriasis. By improving gut barrier function, reducing inflammation, and modulating the immune system, Bifidobacterium may help alleviate symptoms of these conditions. Studies on Bifidobacterium supplementation for eczema, particularly in infants, have shown promising results, aligning with the immune-modulatory effects mentioned earlier.
• Oral Health: While the oral cavity has its own distinct microbiome, the gut microbiome can indirectly influence oral health through systemic inflammation and immune responses. Furthermore, some probiotic strains, including certain Bifidobacterium, have been studied for their ability to inhibit oral pathogens that contribute to cavities and gum disease. However, the primary probiotics for oral health often focus on Lactobacillus species specifically adapted to the oral environment.
• Bone Health: Emerging research suggests a link between the gut microbiome, SCFA production, and bone mineral density. SCFAs, particularly butyrate, may positively influence bone metabolism and mineral absorption (like calcium and magnesium). By promoting SCFA production, Bifidobacterium could potentially play a supportive role in maintaining bone health, although this area requires much more investigation.
• Anti-aging Effects: The decline in Bifidobacterium levels is a common feature of the aging gut microbiome, often associated with increased frailty and inflammation (“inflammaging”). Restoring Bifidobacterium levels through supplementation may help counteract some aspects of age-related gut changes, reduce systemic inflammation, and potentially contribute to healthier aging, although this is a complex area. These diverse potential benefits underscore the far-reaching impact of a healthy gut microbiome populated with beneficial bacteria like Bifidobacterium.

Nuances and Deeper Understanding Species, Strains, and Synergy

To truly understand the benefits of Bifidobacterium, it’s vital to move beyond the genus level and appreciate the nuances that dictate their effects.

• Species and Strain Specificity: As repeatedly emphasized, probiotic benefits are often strain-specific. Bifidobacterium longum NCC3001 has evidence for improving psychological symptoms in IBS, while Bifidobacterium animalis subsp. lactis BB-12 is known for improving constipation. These are distinct strains with distinct effects. A high-quality probiotic supplement will list the specific species and strain (e.g, Bifidobacterium longum 1714™ or Bifidobacterium animalis subsp. lactis BB-12®). The benefits demonstrated in research for one strain cannot be assumed for another, even within the same species.
• Importance of Viable Counts (CFUs): Probiotics must be live and in sufficient numbers to exert their effects. Products are typically measured in Colony Forming Units (CFUs). While higher CFU counts aren’t always better, a dose supported by research for the specific strain is crucial. Furthermore, the CFUs listed should ideally be guaranteed at the end of the product’s shelf life, not just at the time of manufacture.
• Delivery Systems: Getting the bacteria through the acidic stomach and bile-rich small intestine to the large intestine where many Bifidobacterium species reside is challenging. Enteric-coated capsules or formulations designed for stability can improve viability.
• Synergy with Other Microbes (Multi-Species Formulations): In the gut, Bifidobacterium doesn’t work alone. It interacts synergistically with other bacteria. For example, they produce lactate and acetate, which feed butyrate producers. Multi-species probiotic formulations, including Bifidobacterium alongside various Lactobacillus species and others, may offer broader or enhanced benefits compared to single-species products, mimicking the natural diversity of a healthy gut.
• The Role of Prebiotics: Bifidobacterium species thrive on prebiotics (non-digestible fibers and oligosaccharides). Consuming a diet rich in prebiotics (like inulin, FOS, GOS found in onions, garlic, bananas, chicory root, etc.) or taking a synbiotic supplement (combining probiotics and prebiotics) can significantly enhance the survival, growth, and activity of Bifidobacterium in the gut, amplifying their benefits.
• Individual Variability: The response to probiotic supplementation varies greatly among individuals due to differences in their baseline microbiome composition, genetics, diet, lifestyle, and health status. What works for one person may not work the same way for another.
• Transient vs. Resident Effects: Most probiotic strains are transient; they pass through the gut and are eliminated unless regularly consumed. Their benefits occur while they are present and metabolically active. While they may influence the resident microbial community, they don’t typically permanently colonize the gut in large numbers. Recognizing these nuances is essential for making informed decisions about probiotic use and having realistic expectations about their effects.

Choosing Your Bifidobacterium Probiotic What to Look For

Given the species and strain specificity, choosing the right Bifidobacterium probiotic requires careful consideration

1. Identify Your Goal: Are you targeting IBS symptoms, constipation, immune support, or general wellness? Look for products containing species and strains that have been specifically researched for that indication.
2. Check the Specific Strains: Don’t just look for “Bifidobacterium longum”; look for Bifidobacterium longum with a specific strain designation (e.g, 35624, 1714, BB536, etc.). Research the specific benefits associated with that strain.
3. Verify CFU Count: Ensure the product provides a dose (CFUs) that aligns with research demonstrating benefits for the target condition. Look for guarantees of CFU count at the end of shelf life.
4. Consider Viability and Delivery: Does the product have features to ensure the bacteria survive the journey to the gut (e.g, delayed-release capsules, specific packaging)?
5. Look for Quality and Transparency: Choose reputable brands that provide clear labeling of species and strains, CFU counts, and potentially third-party testing for purity and potency.
6. Consider Synbiotics: A product that includes prebiotics known to nourish Bifidobacterium (like FOS or GOS) may be more effective.
7. Consult a Healthcare Professional: Especially if you have underlying health conditions, are pregnant, breastfeeding, or taking medications, consult with a doctor or registered dietitian before starting probiotic supplementation. They can help you choose an appropriate product and integrate it into your overall health plan. Selecting a probiotic based on specific strains and research evidence is key to maximizing the potential benefits of the Bifidobacterium genus.

Conclusion The Enduring Power of Bifidobacterium for Holistic Health

The Bifidobacterium genus represents a cornerstone of a healthy human microbiome, particularly critical in early life but maintaining importance throughout adulthood. As dietary supplements, Bifidobacterium probiotics offer a wide array of potential health benefits, primarily by modulating the gut ecosystem. From their fundamental role in fermenting prebiotics into vital SCFAs and strengthening the gut barrier to their sophisticated interactions with the immune system and the gut-brain axis, Bifidobacterium species exert profound effects on digestive health, immune function, mental well-being, and metabolic processes. They offer therapeutic potential for conditions ranging from IBS and constipation to allergies, anxiety, and even metabolic disorders. However, harnessing the full power of Bifidobacterium requires an appreciation for the scientific nuances – the critical importance of species and strain specificity, adequate dosage, and the synergistic relationship with prebiotics and other beneficial microbes. Probiotic supplementation is not a standalone solution but rather a valuable tool that can support health when integrated into a holistic approach encompassing a balanced diet rich in fiber, a healthy lifestyle, and appropriate medical care. As research continues to unveil the intricate complexities of the microbiome and the specific capabilities of different Bifidobacterium strains, their role in promoting and maintaining human health is only likely to grow, solidifying their status as true powerhouses of the gut.