Manganese Deficiency: Why It Is Uncommon and How Status Is Judged

Manganese deficiency is rarely seen in people who eat a varied diet, because the mineral is present in grains, legumes, nuts, and leafy vegetables at levels that easily meet daily needs. That said, understanding what manganese does in the body, how intake is measured, and what limits are considered safe helps you have a more informed conversation with your healthcare provider.

What Manganese Does in the Body

According to the NIH Office of Dietary Supplements (ODS), manganese serves as a cofactor for a range of enzymes. Three of the most studied are manganese superoxide dismutase, arginase, and pyruvate carboxylase. Through these enzymes, manganese is involved in amino acid metabolism, cholesterol metabolism, glucose metabolism, and carbohydrate metabolism. It also contributes to the body's antioxidant defense by helping neutralize reactive oxygen species.

Manganese also plays a role in bone formation as a cofactor for several bone-related enzymes. The ODS rates the evidence that manganese functions as an enzymatic cofactor supporting normal metabolism as strong. The evidence that it is involved in bone formation is also rated strong. However, the ODS rates evidence that manganese supplementation improves bone mineral density or reduces osteoporosis risk in humans as insufficient, meaning well-designed clinical trials have not yet confirmed a benefit from supplementation beyond correcting an actual deficiency.

Intake Targets Set by the NIH

Unlike many nutrients, manganese does not have a Recommended Dietary Allowance (RDA). The Food and Nutrition Board instead set an Adequate Intake (AI), which is used when evidence is not strong enough to establish a precise requirement. According to the NIH ODS, the AI for manganese is 2.3 mg per day for men aged 19 and older and 1.8 mg per day for women aged 19 and older.

The Tolerable Upper Intake Level (UL) for adults aged 19 and older is 11 mg per day from all sources combined, as reported by the NIH ODS. This limit was set by the Food and Nutrition Board based on levels associated with whole-blood manganese above the normal range and a risk of neurotoxicity. Importantly, the ODS notes that there is no evidence of toxicity from high dietary intakes alone. The UL applies to combined intake from food and supplements, but it does not apply to individuals taking supplemental manganese under medical supervision.

Why True Deficiency Is Uncommon

Manganese is widely distributed in the food supply. Rich sources include whole grains, brown rice, oatmeal, legumes, nuts, seeds, and tea. Because so many staple foods contain meaningful amounts, most people in developed countries meet the AI through diet without trying. The ODS notes that manganese deficiency has not been well characterized in humans, and the evidence that deficiency causes defined clinical signs is rated as limited. Experimental deficiency has been induced in controlled research settings, but spontaneous deficiency from diet alone is considered uncommon in otherwise healthy adults.

Who May Be at Greater Risk

Certain situations can affect manganese absorption or increase the likelihood of lower status. These include:

• People with very low dietary variety or severe malnutrition
• Individuals receiving long-term parenteral nutrition without adequate trace element supplementation
• People with low iron stores, because iron status and manganese absorption are linked (see the section on nutrient interactions below)

If you have concerns about your intake or absorption, speak with a clinician rather than self-diagnosing or starting a supplement without guidance.

How Status Is Assessed

Assessing manganese status in clinical practice is not straightforward. There is no single reliable biomarker that is universally accepted. Whole-blood manganese concentration is the most commonly used measure, and the ODS references whole-blood levels when discussing the upper limit. Serum or plasma manganese and urinary manganese are also used in research settings, but each has limitations related to the body's tight homeostatic control of the mineral. Because manganese status is difficult to pin down with one test, clinicians typically consider dietary intake history alongside any laboratory findings.

The Iron and Manganese Interaction

One of the more clinically relevant nutritional interactions involves iron. The ODS states that dietary iron intake and iron status, measured by serum ferritin, are inversely associated with manganese absorption. In practical terms, low iron status increases manganese absorption, which can be relevant in situations where manganese exposure is elevated, because higher absorption could raise the risk of manganese accumulation. Iron and manganese appear to share an intestinal transporter, which may underlie this competitive relationship. If you have been diagnosed with iron deficiency or iron overload, discuss how this may affect other trace mineral considerations with your doctor or a registered dietitian.

Medications and Supplement Interactions

The ODS states that manganese is not known to have any clinically relevant interactions with medications. Even so, if you are taking any prescription or over-the-counter medications, talk to your doctor or pharmacist before adding a manganese supplement to your routine. This is a general principle of safe supplement use, not a specific concern unique to manganese.

A Note on Supplements

Manganese is available in multivitamin and mineral products as well as standalone supplements. Supplements are not intended to diagnose, treat, cure, or prevent any disease, and these statements have not been evaluated by the FDA. For most adults eating a varied diet, supplementation is unlikely to be necessary. If a clinician has identified a specific reason to consider supplemental manganese, they can advise on an appropriate amount relative to the AI of 2.3 mg per day for men and 1.8 mg per day for women, and well below the UL of 11 mg per day. Do not exceed the UL from combined sources without medical supervision. Always consult a clinician or pharmacist for personal dosing decisions.

Bottom Line

Manganese plays well-established roles as an enzymatic cofactor in metabolism and antioxidant defense, and its involvement in bone-related enzymes is supported by strong evidence. True dietary deficiency is uncommon because the mineral is found in widely consumed foods, and the ODS rates evidence for clinically defined deficiency signs in humans as limited. Status is most often assessed through whole-blood manganese in combination with dietary history. If you have specific concerns about your manganese intake or status, a conversation with your healthcare provider is the right starting point.

References

• NIH Office of Dietary Supplements. Manganese: Health Professional Fact Sheet. https://ods.od.nih.gov/factsheets/Manganese-HealthProfessional/
• NIH Office of Dietary Supplements. Manganese: Consumer Fact Sheet. https://ods.od.nih.gov/factsheets/Manganese-Consumer/
• National Academies of Sciences, Engineering, and Medicine. Dietary Reference Intakes. https://nap.nationalacademies.org/catalog/10026