WikiBiomeThe human microbiome encyclopediaRanked matches across titles, topics, categories, and article introductions.
arsenic (As) is unique among dietary heavy metals because it exists in two fundamentally different forms with dramatically different toxicities: inorganic arsenic (iAs, the dangerous form) and organic arsenic (arsenobetaine, arsenosugars — largely non-toxic). Understand…
cadmium (Cd) enters the human body primarily through food. Unlike nickel, which has high-concentration food categories that can be avoided, cadmium contamination is diffuse — embedded in staple crops, leafy greens, and grains that form the basis of most dietary patterns…
lead (Pb) has no safe level of exposure. Unlike most dietary metals, lead does not play any known biological role — every atom absorbed represents toxic burden. While environmental lead exposure (paint, soil, air) has decreased dramatically since leaded gasoline phase-o…
A synthesis of how dietary heavy metal exposure varies across the human lifespan, highlighting that the same metals present different risks at different developmental stages due to changing absorption rates, detoxification capacity, dietary patterns, and organ vulnerabi…
Food is the primary source of nickel exposure for the general (non-occupational) population. While food nickel poses minimal risk to most adults, children and nickel-sensitized individuals are high-risk groups.
This page addresses the practical question: how do toxic metals get into people? Metal toxicology research identifies the mechanisms of harm, but understanding exposure routes -- dietary, occupational, environmental, and consumer product-mediated -- is essential for pre…
The developing infant represents a uniquely vulnerable window for heavy metal toxicity. Three factors converge to make the first years of life a critical period: an immature and rapidly assembling gut microbiome, a developing blood-brain barrier, and proportionally high…
A cluster of conditions — high blood pressure, impaired fasting glucose, insulin resistance, abdominal obesity (BMI ≥25), high triglycerides, low HDL-C — defined by the presence of ≥3 components. Emerging evidence links MetS to environmental nickel exposure, though find…
Prenatal metal exposure refers to fetal contact with essential and toxic metals during gestation, a critical developmental window when even low-dose exposures can produce lasting effects. Metals cross the placenta with varying efficiency — lead and mercury transfer read…
Research summary -- not medical advice. This page synthesizes published research on why a commonly recommended intervention requires careful consideration in the context of cadmium exposure. Consult a qualified healthcare provider before making changes to supplementatio…
A Gram-negative, aerobic, non-fermenting coccobacillus and a member of the ESKAPE group of priority pathogens (Enterococcus, Staphylococcus, Klebsiella, Acinetobacter, Pseudomonas, Enterobacter). Acinetobacter baumannii is among the most problematic nosocomial pathogens…
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that functions as a master sensor at the intersection of gut microbial metabolism, environmental chemical exposure, and immune regulation. It is expressed broadly across immune cells, intesti…
A Gram-negative, obligate anaerobic, mucin-degrading bacterium that colonizes the intestinal mucus layer and has emerged as one of the most important next-generation probiotics. A. muciniphila is consistently depleted in disease states associated with metal dyshomeostas…
An anti-aging protein that has emerged as a critical mediator between heavy metal exposure and chronic kidney disease progression. Originally discovered as a gene whose mutation caused premature aging in mice, alpha-klotho is now understood to be a multifunctional prote…
A non-essential metal and the most abundant metallic element in the Earth's crust. Unlike manganese, iron, or selenium, aluminum has no known biological function in humans. Its significance in metal toxicology stems from two major concerns: proven neurotoxicity at eleva…
The most common form of dementia, affecting an estimated 55 million people worldwide and projected to triple by 2050 zhang 2024 recent advances alzheimers mechanisms trials. Characterized by progressive memory loss, cognitive decline, amyloid-beta plaques, and neurofibr…
The ability of microorganisms to survive and replicate in the presence of antimicrobial agents — antibiotics, antifungals, antivirals, antiparasitic drugs — at concentrations that would normally inhibit or kill them. Antimicrobial resistance (AMR) is designated by the W…
A metalloid that sits in the shadows of better-studied toxic metals like lead, cadmium, and mercury, yet appears with surprising consistency in metallomic studies of endocrine and inflammatory conditions. Antimony (symbol Sb, from Latin stibium; atomic number 51) exists…
Anxiety disorders are the most prevalent mental health conditions globally, affecting ~280 million people (~4.8% of the world population). They encompass generalized anxiety disorder (GAD), social anxiety, panic disorder, and phobias. In the WikiBiome context, anxiety f…
Aspirin (acetylsalicylic acid) is a non-steroidal anti-inflammatory drug (NSAID) that irreversibly inhibits cyclooxygenase (COX) enzymes, suppressing prostaglandin synthesis. While widely used as an antiplatelet and anti-inflammatory agent, aspirin carries significant i…
Atherosclerosis is a chronic inflammatory disease of arterial walls characterized by lipid-laden plaque formation, endothelial dysfunction, and progressive vascular occlusion. It is the pathological substrate underlying coronary artery disease, stroke, and peripheral ar…
A neurodevelopmental condition affecting approximately 1 in 36 children (US CDC 2023 estimate), characterized by differences in social communication, restricted interests, and repetitive behaviors. From a metallomics perspective, ASD presents a compelling convergence of…
Bacterial vaginosis (BV) is the most common vaginal infection in women of reproductive age, affecting an estimated 29% of women globally. Rather than an infection by a single pathogen, BV represents a polymicrobial dysbiotic state -- a collapse of the protective Lactoba…
Bacteroides caccae is a Gram-negative, obligate anaerobic member of the bacteroidetes phylum and a common fiber-degrading commensal in the human colon. While less individually prominent than bacteroides fragilis or bacteroides thetaiotaomicron, B. caccae has emerged as …
Barrett's esophagus (BE) is a premalignant condition in which the normal squamous epithelium of the distal esophagus is replaced by intestinal-type columnar epithelium (intestinal metaplasia). It is the primary risk factor for esophageal adenocarcinoma (EAC), a cancer w…
A class of Gram-negative bacteria within the phylum Proteobacteria that has emerged as a causal risk factor for schizophrenia and bipolar disorder through Mendelian randomization studies. Betaproteobacteria includes genera with notable metal tolerance -- particularly wi…
Bifidobacterium longum is a Gram-positive, obligate anaerobic bacterium and one of the most important commensal species in human health from infancy through old age. Its subspecies — B. longum subsp. longum (adult gut), B. longum subsp. infantis (infant gut, HMO degrade…
Measurable indicators of biological state, exposure, or disease. In the metallomics context, biomarkers span three interconnected domains: metal biomarkers (quantifying exposure and body burden), microbiome biomarkers (reflecting microbial community disruption), and met…
A heavy metal traditionally considered safe enough for over-the-counter gastrointestinal remedies (Pepto-Bismol, De-Nol), bismuth is re-emerging as a potent antimicrobial synergist. Its key property: Bi3+ competes with Fe3+ for binding sites on siderophores and bacteria…
A selective semipermeable border formed by brain endothelial cells connected by tight junctions, pericytes, and astrocytic end-feet. The BBB restricts passage of most molecules from blood to brain, protecting the CNS from toxins, pathogens, and inflammatory mediators. M…
Breast cancer is the most common cancer in women worldwide, with approximately 2.3 million new cases annually. While genetic, hormonal, and lifestyle factors are well-established risk determinants, the metallomic dimension reveals a consistent pattern of trace element d…
Butyrate is a four-carbon short-chain fatty acid produced when anaerobic gut microorganisms ferment dietary substrates. In the colon, it participates in epithelial energy metabolism, barrier maintenance, immune signaling, and gene regulation. Its effects depend on conce…
Cadmium is a toxic non-essential heavy metal (IARC Group 1 carcinogen) with a biological half-life of 17--30 years in mammals, primarily accumulating in the renal cortex via proximal tubular reabsorption of the Cd-metallothionein complex rasin 2025 cadmium exposure heal…
An opportunistic fungal pathogen whose relationship with metals is multifaceted: C. albicans can biosorb heavy metals from its environment, heavy metal exposure promotes its virulence in immunocompromised hosts, and metal nanoparticles are being developed as antifungal …
Candida tropicalis is an opportunistic fungal pathogen and occasional gut commensal, increasingly recognized as one of the most clinically significant non-albicans Candida (NAC) species. Once considered a distant runner-up to C. albicans, it has emerged as a major drive…
Cardiovascular disease (CVD) -- encompassing atherosclerosis, coronary artery disease, hypertension, myocardial infarction, heart failure, and stroke -- is the leading cause of death globally. The gut-heart axis has emerged as a central paradigm linking microbial metabo…
Celiac disease is a chronic autoimmune condition triggered by dietary gluten (gliadin proteins from wheat, barley, and rye) in genetically susceptible individuals (HLA-DQ2/DQ8, carried by ~30-40% of Europeans but penetrant in only ~1% of carriers). Gluten exposure cause…
Cerebral palsy (CP) is the most common motor disability in childhood, affecting 2-3 per 1,000 live births allen 2021 multi organ dysfunction cerebral palsy. Characterized by non-progressive disturbances in movement and posture arising from injury to the developing brain…
Chromium is a transition metal (atomic number 24) whose toxicology is defined by a stark oxidation-state divide. Hexavalent chromium, Cr(VI), is an IARC Group 1 human carcinogen that causes DNA damage through a unique mechanism of intracellular reduction and ternary add…
A progressive loss of kidney function affecting approximately 850 million people worldwide (10–14% of adults), causing 1.2 million deaths annually. CKD is unique among diseases in this wiki because it occupies both sides of the metal-disease equation: heavy metals (Cd, …
A transition metal that is essential to human health exclusively as a component of cobalamin (vitamin B12), but toxic at higher levels of exposure. Cobalt occupies a distinctive position in metal biology: it is the only metal whose essential biological function in mamma…
A genus of Gram-positive, obligate anaerobic bacteria within the Actinobacteria phylum (family Coriobacteriaceae) that has emerged as a consistent pathobiont enriched in cardiometabolic and autoimmune diseases. C. aerofaciens is the most studied species, with establishe…
The collective ability of the resident gut microbiome to prevent colonization by exogenous pathogens and suppress expansion of resident pathobionts. Colonization resistance is not a property of any single organism but an emergent function of the whole microbial communit…
Colorectal cancer (CRC) is the third most common cancer worldwide and the second leading cause of cancer death. Over 90% of cases are sporadic, driven by a complex interplay between genetic predisposition, dietary habits, gut microbiome composition, and environmental ex…
The co-occurrence of multiple diseases in the same individual at rates exceeding chance. Comorbidity patterns are a central puzzle in medicine -- why do IBD patients develop CVD? Why does PCOS cluster with T2D? Why do neurodegenerative diseases associate with depression…
A chronic, relapsing-remitting inflammatory bowel disease (IBD) characterized by transmural inflammation of the gastrointestinal tract, most commonly affecting the terminal ileum and colon but capable of involving any segment from mouth to anus zhang 2017 intestinal mic…
Debaryomyces is a genus of ascomycetous fungi, with D. hansenii being the most clinically relevant species, that represents a prominent opportunistic pathobiont enriched in inflammatory bowel disease, particularly crohns disease. Unlike many commensal fungi, Debaryomyce…
Depression is the most prevalent mental health disorder globally, affecting over 280 million people zhu 2025 microbiota gut brain axis depression review, and one of the most metal-sensitive conditions in this wiki. It sits at the convergence of nearly every pathway cata…
Disruption of the normal composition and metabolic function of microbial communities, particularly the gut microbiome. In the metallomics context, dysbiosis is both a consequence of metal toxicity and an amplifier of further disease -- creating vicious cycles where meta…
Dysmenorrhea -- painful menstruation -- is the most common gynecological complaint, affecting 50-90% of reproductive-age women. It is classified as primary (no identifiable pelvic pathology) or secondary (caused by conditions such as endometriosis, adenomyosis, or fibro…
Membrane-spanning protein complexes that actively export substrates from the bacterial cell, using energy from ATP hydrolysis or the proton motive force. In the context of metal-microbiome biology, efflux pumps serve a dual role that has profound clinical consequences: …
A Gram-positive obligate anaerobe and key estrobolome member that links metabolic dysbiosis to hormone-driven diseases, particularly endometriosis. E. lenta is remarkable for its ability to inactivate cardiac glycosides (like digoxin) and to produce beta-glucuronidase, …
Endometriosis is a chronic estrogen-dependent inflammatory condition affecting approximately 10% of reproductive-age women, characterized by the growth of endometrial-like tissue outside the uterus colonetti 2023 gut vaginal microbiota endometriosis meta analysis. The c…
A genus of Gram-positive bacteria (primarily E. faecalis and E. faecium) that exemplifies the metal-antibiotic resistance co-selection crisis. Enterococci carry diverse metal tolerance genes for mercury, arsenic, copper, and cadmium on the same mobile genetic elements a…
Enterococcus faecium is a Gram-positive, facultatively anaerobic bacterium that epitomizes the metal-antibiotic co selection problem in modern medicine. As one of the six ESKAPE pathogens (the group responsible for the majority of hospital-acquired infections that fail …
Epigenetic modifications — heritable changes in gene expression without altering the DNA sequence — are a primary mechanism through which both heavy metals and the gut microbiome influence disease across the lifespan. The three major epigenetic mechanisms (DNA methylati…
Epigenetics is the study of heritable changes in gene expression that occur without alterations to the DNA sequence itself. These changes -- primarily DNA methylation, histone modifications, and non-coding RNA regulation -- represent a molecular memory system that can b…
Epilepsy is a chronic neurological disorder characterized by recurrent unprovoked seizures, affecting ~50 million people worldwide. Approximately 30% of patients have drug-resistant epilepsy -- a population where microbiome-targeted interventions (particularly the ketog…
Erectile dysfunction (ED) affects 30-50% of men aged 40-70 Feldman et al. 1994, with prevalence increasing with age. Conventionally understood as a vascular and/or neurogenic disorder, ED is now recognized as a condition with a significant gut microbiome component -- th…
A Gram-negative bacterium that spans the commensal-pathogen spectrum, with pathogenic variants (UPEC, STEC, EHEC) deploying nickel-dependent enzymes as virulence factors. E. coli is the model organism for nickel transport biology -- the NikABCDE system was first charact…
Affects approximately 48 million women worldwide (WHO global infertility prevalence estimates). From a microbiome-metallomics perspective, female infertility sits at the intersection of the estrobolome (microbial estrogen metabolism), heavy metal reproductive toxicity (…
The Fenton reaction is the iron-catalyzed generation of hydroxyl radicals (OH.) from hydrogen peroxide -- the most reactive oxygen species in biology. Discovered by H.J.H. Fenton in 1894, this reaction is the mechanistic bridge between metal accumulation and oxidative t…
Fibromyalgia (FM) is a chronic pain syndrome affecting 2-4% of the global population Heidari et al. 2017, characterized by widespread musculoskeletal pain, fatigue, cognitive dysfunction ("fibro fog"), and sleep disturbances. Conventionally attributed to central sensiti…
Firmicutes (recently reclassified as Bacillota) is the dominant bacterial phylum in the Western adult gut, comprising the core community of short-chain fatty acid (SCFA) producers that maintain intestinal barrier integrity, regulate immune function, and influence system…
Gardnerella vaginalis is a Gram-variable, facultatively anaerobic bacterium that is the key organism in bacterial vaginosis (BV), the most common vaginal infection in women of reproductive age. Its sialidase production, biofilm-forming capacity, and associations with he…
The fifth most common cancer worldwide and third leading cause of cancer death, with over 1 million new cases annually. Gastric cancer stands unique in this wiki as the disease where a single microorganism -- helicobacter pylori -- provides the dominant causal pathway, …
Gastroesophageal reflux disease (GERD) is a chronic condition in which stomach acid or bile flows back into the esophagus, causing mucosal damage and symptoms such as heartburn and regurgitation. Affecting approximately 20% of Western populations, GERD is conventionally…
Alphabetical definitions of specialist terms used throughout this wiki. Where a full concept page exists, the term links to it. --- AhR (aryl hydrocarbon receptor) -- A ligand-activated transcription factor that senses microbial metabolites (especially indoles from tryp…
Graves' disease (GD) is an autoimmune thyroid disorder characterized by TSH receptor antibodies (TRAb) that stimulate the thyroid gland, causing hyperthyroidism kahaly 2022 graves disease targeted therapy review. It is the most common cause of hyperthyroidism, with conc…
The community of trillions of microorganisms — bacteria, archaea, fungi (mycobiome), viruses, and bacteriophages — inhabiting the human gastrointestinal tract, with the highest density in the colon (~10¹¹ cells/g). The gut microbiome encodes 100–150 times more genes tha…
Bidirectional communication between the gut microbiota and the central nervous system, mediated by neural (vagus nerve, enteric nervous system), immune (cytokines, microglia), endocrine (HPA axis), and metabolic (SCFAs, neurotransmitter precursors, tryptophan metabolite…
The relationship between heavy metals and the gut microbiota is bidirectional: metals reshape microbial community composition and metabolic output, while the microbiota modulates metal absorption, speciation, and toxicity. The gut microbiota serves as the first line of …
Hashimoto's thyroiditis (HT) is the most common autoimmune disease globally and the leading cause of hypothyroidism. Chronic lymphocytic infiltration of the thyroid gland progressively destroys follicular architecture, reducing thyroid hormone output. Prevalence is 5-10…
Heavy metals is a widely used but chemically imprecise umbrella term for elements discussed because of their density, persistence, environmental occurrence, or toxicity. One common convention uses density above 5 g/cm3, but density alone does not determine biological ha…
The 6-24 month developmental window — when infants transition from breast milk to solid foods — represents a convergence of maximum vulnerability and maximum exposure. Immature detoxification systems, rapid organ development, and high food-to-body-weight ratios mean tha…
Hyperaccumulator plants are species that concentrate heavy metals in their tissues at 10–100× the levels found in non-accumulating species growing in the same soil. Over 700 plant species are known hyperaccumulators — primarily for nickel (~530 species), but also zinc, …
Hyperparathyroidism is the overproduction of parathyroid hormone (PTH), a master regulator of calcium homeostasis. While primary hyperparathyroidism (from parathyroid adenoma) is well described, the WikiBiome framework highlights secondary hyperparathyroidism -- the com…
Sustained elevation of systemic blood pressure, affecting an estimated 1.3 billion adults worldwide and the leading modifiable risk factor for cardiovascular disease, stroke, and chronic kidney disease. The gut microbiome-blood pressure axis has emerged as a major resea…
An umbrella term for chronic relapsing-remitting inflammatory conditions of the gastrointestinal tract, principally crohns disease (CD; transmural, any GI segment) and ulcerative colitis (UC; mucosal, colon only). Approximately 6 million patients worldwide. IBD represen…
A condition in which cells fail to respond normally to insulin, requiring progressively higher insulin levels to maintain glucose homeostasis. Insulin resistance is central to PCOS, type 2 diabetes, and metabolic syndrome, and has extensive but complex connections to me…