Maganese
Also known as: Manganese, Mn
Overview
Manganese (Mn) is an essential trace mineral, atomic number 25, naturally found in various foods like nuts, legumes, whole grains, leafy green vegetables, and tea, as well as in drinking water and dietary supplements. It functions as a crucial cofactor for numerous enzymes involved in vital physiological processes, including metabolism, antioxidant defense (notably as part of manganese superoxide dismutase, MnSOD), bone formation, and wound healing. While essential for normal bodily functions, manganese has a narrow therapeutic window, meaning there's a fine line between adequate intake and potential toxicity. Supplements are sometimes marketed for bone and joint health or metabolic support, but evidence for independent benefits beyond dietary intake is limited. Research on manganese is moderately mature, with findings often derived from observational studies, some randomized controlled trials (RCTs), and systematic reviews, though large-scale RCTs specifically isolating manganese's effects are scarce.
Benefits
Manganese offers several potential benefits, primarily through its role as an enzymatic cofactor. A meta-analysis of observational studies suggests that higher dietary manganese intake is significantly associated with a reduced risk of depression, particularly in females (Relative Risk (RR) = 0.71; 95% CI: 0.58–0.86; p < 0.001). This indicates a moderate and statistically significant association, though causality is not definitively established. For osteoarthritis, two RCTs using combination supplements containing manganese ascorbate (30-40 mg elemental Mn/day) alongside glucosamine and chondroitin showed benefits in reducing knee pain compared to placebo. However, manganese's independent contribution to these effects was not isolated. Manganese is also critical for the function of manganese superoxide dismutase (MnSOD), a powerful antioxidant enzyme that helps protect cells from oxidative stress. Conversely, systematic reviews and meta-analyses have found no significant overall association between manganese exposure and the risk of metabolic syndrome, with evidence being inconclusive.
How it works
Manganese primarily functions as an essential cofactor for several key enzymes in the body. Its most notable role is as a component of manganese superoxide dismutase (MnSOD), a potent antioxidant enzyme located in the mitochondria. MnSOD plays a critical role in protecting cells from oxidative damage by converting harmful superoxide radicals into less reactive molecules. Beyond antioxidant defense, manganese is involved in various metabolic pathways, including the metabolism of amino acids, cholesterol, and glucose, through enzymes like arginase and pyruvate carboxylase. It is also required for enzymes crucial for bone formation. Manganese is absorbed in the small intestine, with its bioavailability influenced by dietary factors such as phytates and iron intake. Excess manganese is primarily excreted via bile, with its actions concentrated in the mitochondria, liver, brain, and bone tissue.
Side effects
Manganese is generally safe at dietary intake levels. However, there is a significant risk of toxicity with excessive intake or impaired excretion, particularly in individuals with liver disease. At typical dietary or supplemental doses, common side effects are not reported. Rare but severe side effects, primarily associated with chronic high exposure (e.g., occupational or environmental), include manganism, a neurological disorder resembling Parkinson's disease. There are potential interactions with other minerals; for instance, iron, calcium, and phosphorus can affect manganese absorption. No major drug interactions have been reported. Contraindications include liver disease or any condition that impairs biliary excretion, as these can lead to manganese accumulation and increased toxicity risk. Older adults may also be at an increased risk of manganese accumulation due to potentially decreased clearance mechanisms, necessitating caution with supplementation.
Dosage
The adequate intake (AI) for manganese is 2.3 mg/day for adult men and 1.8 mg/day for adult women. There is no established optimal dosage range beyond these AI levels, and supplementation beyond these amounts is generally not recommended due to potential toxicity concerns. The Tolerable Upper Intake Level (UL) for adults is typically around 11 mg/day, though the European Food Safety Authority (EFSA) is currently reviewing these limits. Specific timing for manganese intake is not required. In studies for osteoarthritis, manganese ascorbate was used at doses of 30-40 mg elemental manganese per day, but these were in combination supplements, and manganese's independent effect was not isolated. Absorption of manganese can be reduced by dietary factors such as phytates and high iron intake. No specific cofactors are required for manganese absorption, but a balanced diet is always recommended.
FAQs
Is manganese supplementation necessary?
Manganese supplementation is generally not needed if your diet is adequate. Supplementation beyond the recommended adequate intake is not typically advised due to potential toxicity concerns.
Is manganese safe long-term?
Manganese is safe at dietary levels. However, high doses or impaired excretion, especially with liver issues, can lead to toxicity over the long term, causing neurological problems.
Can manganese improve mood?
Observational studies suggest a link between higher dietary manganese intake and a lower risk of depression, particularly in women. However, this is an association, and causality is not yet definitively established.
Does manganese help metabolic syndrome?
Current evidence is inconclusive regarding manganese's effect on metabolic syndrome. Systematic reviews have not found a strong association, and more research is needed.
Does manganese help joint pain?
Some studies show benefits for joint pain when manganese is part of combination supplements with glucosamine and chondroitin. However, manganese's independent effect on joint pain is not clear.
Research Sources
- https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2022.854774/full – This meta-analysis of observational studies found a significant inverse association between dietary manganese intake and depression risk, particularly in females. The study reported a Relative Risk of 0.71, suggesting a moderate reduction in risk, but acknowledged limitations inherent to observational designs.
- https://pmc.ncbi.nlm.nih.gov/articles/PMC8876230/ – This systematic review and meta-analysis, which included 12 studies, investigated the association between manganese exposure and metabolic syndrome risk. The findings indicated no statistically significant overall association between various forms of manganese exposure (dietary, serum, urine, whole blood) and metabolic syndrome risk, highlighting study heterogeneity as a limitation.
- https://lpi.oregonstate.edu/mic/minerals/manganese – This review summarizes two randomized controlled trials where combination supplements containing manganese ascorbate (30-40 mg/day) along with glucosamine and chondroitin reduced knee osteoarthritis pain. It notes that manganese's independent contribution to these effects was not isolated and emphasizes safety and dosing guidelines, particularly regarding avoiding excessive intake.
- https://pubmed.ncbi.nlm.nih.gov/35215474/ – This PubMed entry corresponds to the Wong et al. (2022) systematic review and meta-analysis on metabolic syndrome. It confirms the finding of no significant overall association between manganese exposure and metabolic syndrome risk, reinforcing the inconclusive nature of the evidence.
- https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2023.8413 – This EFSA Scientific Opinion indicates that systematic reviews of human and animal data are ongoing to assess tolerable upper intake levels for manganese. It suggests a current UL around 11 mg/day for adults but advises caution due to potential neurotoxicity at high exposures, reflecting an ongoing evaluation of safety limits.