Manganese

What is manganese and what does it do in the body?

According to the NIH Office of Dietary Supplements, manganese is an essential trace element and a cofactor of enzymes such as manganese superoxide dismutase, arginase, and pyruvate carboxylase; through these enzymes, it takes part in amino acid, cholesterol, glucose, and carbohydrate metabolism, clearance of reactive oxygen species, bone formation, reproduction, and the immune response. It also has a role in blood clotting together with vitamin K. ^[1]

The human body carries about 10–20 mg of manganese; 25–40% of it is in bone. Tissue levels are held constant by control of absorption and excretion: more than 90% of absorbed manganese is excreted in feces via bile, and very little leaves in urine. ^[1] Only 1–5% of manganese in food is absorbed; absorption increases at low intake and decreases at high intake. Iron intake and iron stores (ferritin) are inversely related to manganese absorption; men absorbing less manganese than women has been linked to iron status generally being higher in men. ^[1]

That a mineral takes part in enzymes does not mean that taking more than the requirement would improve the functioning of those enzymes. In this guide, “role in the body,” “deficiency,” and “effect of additional supplementation” are treated as separate questions.

How much manganese is needed daily?

The US Food and Nutrition Board (FNB), on which NIH relies, found in 2001 that there were not enough data to derive an estimated average requirement (EAR) for manganese and set “adequate intake” (AI) values for all ages based on customary intakes. ^[1] The European Food Safety Authority (EFSA) also gives an AI for adults; the Türkiye Dietary Guidelines (TÜBER 2022) list the adult value as an AI. ^{[3] [2]}

The NIH table gives 2.3 mg for men and 1.8 mg for women aged 51 and over. ^[1] The values of the three documents do not arrive at the same number; all are AIs and are intended for population-level planning, not individual dose recommendations. EFSA’s summary report also states the same 3.0 mg AI for pregnancy and lactation. ^[3]

Which foods contain manganese?

NIH lists whole grains, mussels, oysters, nuts, soy and other legumes, rice, leafy vegetables, coffee, tea, and spices such as black pepper as sources of manganese. The groups contributing most in US adults are grain products, tea, and vegetables. It is found in drinking water at levels of 1–100 µg/L. ^[1] In TÜBER Table 2.2, rich sources of manganese are given as “dried legumes, oilseeds, shelled dried nuts, green leafy vegetables, and tea.” ^[2]

The table belongs to NIH’s US servings; values of products in Türkiye may differ. In the NIH table, milk, yogurt, chicken breast, ground beef, and hard-boiled egg appear as 0.0 mg. ^[1]

Does manganese deficiency occur?

According to NIH, manganese deficiency in humans is very rare and its symptoms have not been clearly determined; very limited data point to the possibility of bone mineral loss and growth retardation in children, skin rash, lightening of hair color, low serum cholesterol, and high alkaline phosphatase in men, and mood changes and increased premenstrual pain in women. There is no group known to be at risk of deficiency. ^[1] Manganese status is not measured in routine clinical practice; the normal whole-blood range is given as 4–15 µg/L, but levels are highly variable and their usefulness as a status indicator is uncertain. ^[1]

TÜBER Table 2.2 lists the symptoms of manganese inadequacy as “carbohydrate-fat metabolism problems, skin ulcers, infections, moderate intellectual disability.” ^[2] NIH, however, reports that symptoms are not clearly defined and human data are very limited; the wording of the two documents is not equally certain. ^[1]

Is manganese supplementation useful for bone health?

In animals, manganese deficiency can reduce bone formation and density, and supplementation can increase them. According to NIH, the evidence from studies looking at the relationship between circulating manganese level, bone density, and osteoporosis in humans is very limited and inconsistent: in one study, serum manganese of 10 women with osteoporosis was lower than that of 20 women without osteoporosis (20 µg/L, 40 µg/L), whereas in 77 postmenopausal women with osteoporosis and 61 without, no difference was found in erythrocyte and plasma levels. ^[1]

Manganese alone has not been examined in a clinical study for bone health. The only mixture study found is a two-year, double-blind, placebo-controlled trial in 59 healthy postmenopausal women (mean age 66): in the group given zinc (15 mg), manganese (5 mg), and copper (2.5 mg) in addition to 1,000 mg of calcium, spinal density changed by +1.48%, whereas in the placebo group it was −3.53%; the only significant group difference is between placebo and the calcium plus trace mineral group (P = 0.0099). Because manganese, zinc, and copper were given together, the share of manganese cannot be distinguished; the study is small and it is a single study. ^[9] NIH also states that the effect of manganese alone could not be determined. ^[1]

What is the relationship between manganese and type 2 diabetes?

Observational studies have reported an association between both high and low blood manganese and the frequency of diabetes; in some other studies, no association was found. In a case-control study in China with 1,614 participants with newly diagnosed type 2 diabetes and 1,614 controls, a U-shaped association was seen between plasma manganese and diabetes: compared with the middle tertile, the odds ratio was 1.89 (95% CI 1.53–2.33) in the lowest tertile and 1.56 (95% CI 1.23–1.97) in the highest tertile. ^[8] In addition to the same study, NIH reports a study in China with 122 newly diagnosed people with diabetes and 429 controls in which the odds of diabetes were 7.88 times higher in those in the highest tertile, and a study in Sardinia in which blood manganese was lower in people with diabetes. ^[1]

These studies are cross-sectional or case-control; they do not show causality and their directions conflict with one another. In animal research, it has been suggested that manganese supplementation may improve glucose tolerance; according to NIH, there is no clinical study in humans. ^[1]

Is excess manganese harmful?

NIH states that there is no evidence of toxicity from high manganese intake from food sources. Toxicity has been reported in workers who inhale manganese dust for long periods in welding and mining and, in some cases, in people who drink water containing manganese up to 28 mg per liter. Symptoms include tremor, muscle spasms, tinnitus, hearing loss, and imbalance; in advanced cases, a picture resembling Parkinson’s disease may be seen, with changes in gait and balance, tremor, and rigidity. Because iron deficiency increases manganese absorption, it can worsen toxicity symptoms; in chronic liver disease, excretion via bile is impaired, so susceptibility to nervous system toxicity increases. ^[1]

NIH’s tolerable upper intake level (UL) is based on whole-blood manganese level rising above the normal range and the risk of neurotoxicity; it is 11 mg for ages 19 and over, including pregnancy and lactation (9 mg for ages 14–18). The UL does not apply to people taking manganese supplements under medical supervision and is an upper limit for customary daily intake; it is not the limit of a single serving. ^[1] NIH reports that multivitamin-mineral products containing manganese typically contain 1.0–4.5 mg, and most products containing only manganese or a few nutrients carry 5–20 mg of manganese; the same source also states that there are no data on the relative bioavailability of different manganese compounds. ^[1]

The institutions’ approaches to upper limits differ. EFSA’s 2025 UL summary reports that there were not enough data to derive a UL for manganese (EFSA NDA Panel, 2023) and that instead an 8 mg/day “safe intake level” was set for adults, pregnant women, and breastfeeding women; the document states that this level is not a UL, that exceeding it does not mean there is a risk, and that it cannot be used to define the part of the population at risk. ^[4] TÜBER Annex 1.5.5 lists ULs of 11 mg for adult men, 9 mg for women aged 19–50, 11 mg for women aged 51–64, and 9–11 mg in pregnancy and lactation. ^[2]

What is manganese in drinking water associated with in children?

In a cross-sectional study of 362 children (aged 6–13) living in communities supplied by groundwater, the median manganese level in household tap water was found to be 34 µg/L (range 1–2,700 µg/L); a tenfold increase in water manganese was associated with a 2.4-point decrease in IQ (95% CI −3.9 to −0.9) after adjustment for factors such as maternal intelligence and income; the difference between the lowest and highest quintiles of water manganese is 6.2 points. Hair manganese increased with the amount taken in via water and did not increase with the amount taken in via food. ^[6] In the 2013 systematic review, of 41 articles examining arsenic, cadmium, and manganese, 17 are on manganese; 14 of the manganese studies reported a significant adverse effect on neurodevelopment or behavioral disorders, and in the meta-analysis a 50% increase in hair manganese was associated with a 0.7-point decrease in IQ in children aged 6–13. ^[7]

The WHO chemical fact sheet gives a provisional guideline value of 0.08 mg/L (80 µg/L) for total manganese; the value was set to be protective against neurological effects in the most sensitive subgroup, bottle-fed infants, and is “provisional” because of the high uncertainty (composite uncertainty factor of 1000); the derivation is based on observations in rats. The same document states that epidemiological studies have limited use in risk assessment because of uncertainty in exposure level, an unclear temporal relationship, and confounders, but that they provide qualitative support that the neurological effects in animal studies are relevant to humans. ^[5]

Does manganese interact with drugs?

NIH states that there are no known clinically significant drug interactions for manganese. ^[1]

How are manganese supplements and drinking water regulated in Türkiye?

Ministry of Agriculture and Forestry approval is mandatory for every food supplement to be placed on the market in Türkiye. ^[14] According to Article 5 of Communiqué 2013/49 as amended by 2015/44, in food supplements only the vitamins and minerals listed in Annex-1 are used in the forms specified in Annex-2, daily maximum limits are determined in accordance with Annex-3 on the basis of the label declaration, and in products containing vitamins and minerals the amount stated on the label is at least 15% of the nutrient reference value for ages 11 and over. ^[11] Statements claiming to prevent, treat, or cure a disease cannot appear in labeling, presentation, and advertising. ^[12]

The Ministry’s Restricted Substances List (September 21, 2026) does not carry a separate row with a daily amount limit for manganese; the list shows “chemical synthesis” as the source for “Manganese (mg)” only in the table “Sources Used Before December 31, 2025 for Vitamins and Minerals.” Because manganese is not a botanical substance, the Plant List does not apply. ^[13]

For manganese in drinking water, the published text of Türkiye’s 2005 Regulation on Waters Intended for Human Consumption contains a value of 50 µg/L as an “indicator parameter”; this is a different category from WHO’s provisional health-based value of 80 µg/L. ^{[10] [5]}

Evidence table: claim, population, and limits

A personal dose or supplementation decision for manganese is made by evaluating diet, kidney-liver status, iron level, and the total content of the products used together; this guide does not recommend personal doses.