Manganism: What Happens When Manganese Exposure Goes Too High

By Erin Rose · Updated July 20, 2026 · Methodology

Educational summary — not medical advice. Nothing on this page is a reason to fear ordinary dietary manganese or a modest AI-range supplement in a healthy adult with normal liver function — see the specific risk groups named below. This statement has not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease.

The occupational literature: a clean dose-response neurotoxic syndrome

Racette BA, Searles Nielsen S, Criswell SR, Sheppard L, Seixas N, Warden MN. "Dose-dependent progression of parkinsonism in manganese-exposed welders." Neurology. 2017 is a longitudinal occupational cohort. PRIMARY ENDPOINT: progression of parkinsonian motor signs (UPDRS-based) over time in relation to cumulative manganese exposure dose. FINDING: higher cumulative welding-fume manganese exposure was associated with faster progression of parkinsonian signs — a clean dose-response result in a peer-reviewed neurology journal. LIMIT: this is an occupational cohort of welders; exposure levels (chronic inhalation of fume) are far above anything relevant to dietary or oral-supplement intake, and this study does not describe or imply any risk from oral supplement dosing.

Baker MG, Criswell SR, Racette BA, Simpson CD, Sheppard L, Checkoway H. "Neurological outcomes associated with low-level manganese exposure in an inception cohort of asymptomatic welding trainees." Scandinavian Journal of Work, Environment & Health. 2015 followed previously unexposed welding trainees from the start of their careers. PRIMARY ENDPOINT: subclinical neurological and motor changes in this newly exposed cohort. FINDING: measurable neurological changes were detected even at relatively low-level, early-career exposure — useful for showing the effect isn't confined to decades of heavy exposure. LIMIT: still an occupational inhalation cohort with small effect sizes at this early stage; not evidence of harm at trivial (dietary/supplement) exposure levels.

Two review papers frame the syndrome itself. Kwakye GF, Paoliello MM, Mukhopadhyay S, Bowman AB, Aschner M. "Manganese-Induced Parkinsonism and Parkinson's Disease: Shared and Distinguishable Features." International Journal of Environmental Research and Public Health. 2015 explains that manganism and idiopathic Parkinson's disease share parkinsonian motor signs but differ in brain-distribution pattern and levodopa responsiveness — related but clinically separable conditions, cited here for synthesis and definitions, not a specific effect-size claim. Roels HA, Bowler RM, Kim Y, Claus Henn B, Mergler D, Hoet P. "Manganese exposure and cognitive deficits: a growing concern for manganese neurotoxicity." Neurotoxicology. 2012 is a broader synthesis review connecting occupational and environmental (water/air) manganese exposure to cognitive deficits, used here as an umbrella citation linking the occupational and water-exposure threads below.

Drinking water: a real, underrecognized exposure pathway

Private or unregulated wells and some groundwater sources carry naturally elevated manganese — a genuinely actionable, underrecognized exposure pathway most people have never heard of. Bouchard MF, Sauvé S, Barbeau B, Legrand M. "Intellectual impairment in school-age children exposed to manganese from drinking water." Environmental Health Perspectives. 2011 is a cross-sectional cohort study of 362 Quebec children. PRIMARY ENDPOINT: full-scale IQ (WISC-IV) in relation to water-manganese concentration. FINDING: higher water-manganese was associated with lower full-scale IQ scores — a statistically significant inverse association. LIMIT: cross-sectional and observational, so it cannot establish causation alone; residual confounding (socioeconomic status, other co-exposures) is possible despite adjustment.

Dion LA, Saint-Amour D, Sauvé S, Barbeau B, Mergler D, Bouchard MF. "Changes in water manganese levels and longitudinal assessment of intellectual function in children exposed through drinking water." Neurotoxicology. 2018 is a longitudinal follow-up of that cohort. PRIMARY ENDPOINT: change in intellectual function measures over time in relation to change in water-manganese exposure. FINDING: the longitudinal design strengthens the cross-sectional Bouchard 2011 finding by tracking the same children as their exposure changed. LIMIT: still observational, with a smaller follow-up sample than the original cohort — report the direction of association rather than a precise effect size.

Wasserman GA, Liu X, Parvez F, Factor-Litvak P, Kline J, Siddique AB. "Child Intelligence and Reductions in Water Arsenic and Manganese: A Two-Year Follow-up Study in Bangladesh." Environmental Health Perspectives. 2016 is a prospective follow-up cohort with an exposure-reduction (well-switching) component. PRIMARY ENDPOINT: change in child intelligence test scores associated with reduction in well-water arsenic and manganese over two years. FINDING: reductions in water-manganese exposure were associated with improvements in some intelligence measures — the closest thing in this evidence base to a "reducing exposure helps" signal, rather than pure cross-sectional association. LIMIT: exposure reduction happened via well-switching, not a randomized intervention; co-exposure to arsenic complicates isolating the manganese-specific effect; and the Bangladesh population differs geographically and dietarily from a US consumer audience.

Liver disease and long-term parenteral nutrition: the single most important carve-out

Manganese is cleared from the body primarily via bile. When that excretion pathway is impaired (liver disease) or bypassed entirely (long-term parenteral or enteral nutrition), manganese accumulates measurably in the brain — this is the single most clinically important safety carve-out in this cluster.

Spahr L, Butterworth RF, Fontaine S, Bui L, Therrien G, Milette PC. "Increased blood manganese in cirrhotic patients: relationship to pallidal magnetic resonance signal hyperintensity and neurological symptoms." Hepatology. 1996 is a clinical cohort of cirrhotic patients. PRIMARY ENDPOINT: correlation between blood manganese, pallidal MRI T1 hyperintensity, and neurological/extrapyramidal symptoms in cirrhosis. FINDING: cirrhotic patients had elevated blood manganese that correlated with pallidal MRI signal changes and neurological symptoms — the foundational paper establishing that impaired hepatic/biliary excretion causes manganese accumulation with a visible imaging correlate and clinical symptoms. LIMIT: cirrhosis-specific population; correlational — cannot isolate manganese as the sole cause of neurological symptoms in liver disease (hepatic encephalopathy has multiple contributors), but the imaging/blood-level correlation itself is well-established.

Jin J, Saqui O, Allard JP. "Effect of Discontinuation of Manganese Supplementation From Home Parenteral Nutrition Solutions on Whole-Blood Levels and Magnetic Resonance Imaging of the Brain: A 5-Year Cohort Study." JPEN Journal of Parenteral and Enteral Nutrition. 2018 is a prospective cohort of home parenteral nutrition (PN) patients. PRIMARY ENDPOINT: change in whole-blood manganese and brain MRI signal (T1-weighted pallidal signal) after removing supplemental manganese from PN solutions. FINDING: discontinuing manganese supplementation in PN solutions reduced whole-blood manganese and improved/normalized the MRI signal changes over 5 years of follow-up — direct evidence that PN-route manganese accumulates, and that removing it reverses the imaging finding. LIMIT: small, specific clinical population (home PN patients) — not generalizable to oral supplement use in people with normal liver/biliary function.

Abdalian R, Saqui O, Fernandes G, Allard JP. "Effects of manganese from a commercial multi-trace element supplement in a population sample of Canadian patients on long-term parenteral nutrition." JPEN Journal of Parenteral and Enteral Nutrition. 2013 is a cross-sectional/cohort study of long-term PN patients. PRIMARY ENDPOINT: blood manganese levels in relation to the manganese content of the multi-trace-element PN additive product used. FINDING: patients receiving standard commercial multi-trace-element PN additives (which include manganese) showed elevated blood manganese levels — supporting the clinical practice shift toward reducing or removing manganese from PN formulations in long-term patients. LIMIT: specific PN population; observational, establishing association rather than a randomized dose-response result.

Iinuma Y, Kubota M, Uchiyama M, Yagi M, Kanada S, Yamazaki S. "Whole-blood manganese levels and brain manganese accumulation in children receiving long-term home parenteral nutrition." Pediatric Surgery International. 2003 is a clinical cohort of pediatric long-term home PN patients. PRIMARY ENDPOINT: whole-blood manganese and brain MRI manganese-accumulation signal in children on long-term home PN. FINDING: children on long-term home PN accumulated measurable brain manganese, paralleling the adult PN findings above — reinforcing that this is a route-of-administration/excretion-capacity issue, not unique to adults. LIMIT: small pediatric clinical cohort, specific to a medically fragile PN-dependent population — not relevant to healthy children's dietary or supplement intake.

What this evidence does not support

Frequently asked questions

Related

• Manganese: what it is & who actually might need it
• Manganese dosage guide — AI vs UL, and why the UL is neurotoxicity-based
• Best manganese — the specific over-UL products named directly
• Manganese in bone & calcium formulas

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