Manganese is essential mineral, which is naturally present in foods or often added to food supplements. Manganese is a cofactor for many enzymes, including manganese superoxide dismutase, arginase, and pyruvate carboxylase.
Manganese participates in the action of these enzymes:
- in the metabolism of amino acids, cholesterol, glucose and carbohydrates
- removal of reactive oxygen species
- in bone formation
- in reproduction
- in the immune response
Manganese together with vitamin K also plays an important role in blood coagulation and hemostasis.
This trace element is absorbed in the small intestine. After absorption, some manganese remains free, but most of it binds to transferrin, albumin and plasma alpha-2-macroglobulin. Manganese is absorbed by the liver and other tissues.
The human body contains about 10-20 mg of manganese, of which 25-40 % is in bones. The liver, pancreas, kidneys and brain also contain manganese. The body maintains a stable concentration of manganese in tissues by regulating manganese absorption and excretion. More than 90% of the absorbed manganese in % is excreted in the bile in the feces, and a small amount is reabsorbed. Very little is excreted in the urine.
Manganese levels are difficult to estimate and are not routinely measured in clinical practice. Normal blood manganese levels range from 4 to 15 mcg/L. Some studies that measured serum or plasma manganese concentrations in apparently healthy adults reported a mean serum concentration of 1.04 mcg/L and a mean plasma concentration of 1.28 mcg/L.
Although urinary manganese levels decrease with severe deficiency, it is not clear whether this is a good indicator of manganese status.
Recommended doses of manganese
Recommendations for the intake of manganese and other nutrients:
| Table 1. Sufficient intake of manganese | ||||
| Age | A man | A woman | During pregnancy | When feeding |
| from birth to 6 months* | 0.003 mg | 0.003 mg | ||
| 7-12 months | 0.6 mg | 0.6 mg | ||
| 1-3 years | 1.2 mg | 1.2 mg | ||
| 4-8 years | 1.5 mg | 1.5 mg | ||
| 9-13 years old | 1.9 mg | 1.6 mg | ||
| 14-18 years old | 2.2 mg | 1.6 mg | 2.0 mg | 2.6 mg |
| 19-50 years old | 2.3 mg | 1.8 mg | 2.0 mg | 2.6 mg |
| 51+ years old | 2.3 mg | 1.8 mg |
* For infants from birth to 6 months of age, the amount is based on the average manganese intake of infants fed primarily breast milk.
Manganese sources
Food
Manganese is found in a variety of foods, including whole grains, shellfish, oysters, mussels, nuts, soybeans and other legumes, rice, leafy vegetables, coffee, tea, and many spices such as black pepper.
Drinking water also contains trace amounts of manganese, ranging from 1 to 100 mcg/L.
Manganese concentrations range from 3 to 10 mcg/L in breast milk and 30 to 100 mcg/L in cow's milk infant formulas. Soy infant formula has a higher concentration of manganese, 200-300 mcg/L, than formula milk. Studies show that the absorption of manganese from breast milk (8.2 %) is much higher than from soy milk formula (0.7 %) and cow's milk formula (3.1 %).
Humans absorb only about 1-5 % of dietary manganese. Babies and children tend to absorb higher amounts of manganese than adults. In addition, manganese absorption efficiency increases with low manganese consumption and decreases with higher manganese consumption.
Dietary iron intake and iron status (as measured by serum ferritin) are inversely related to manganese absorption. A common transporter of iron and manganese in the gut may play a role. In addition, men seem to absorb dietary manganese less efficiently than women, possibly because iron levels are generally higher in men.
Selected dietary sources of manganese are presented in Table 2.
| Manganese content in food products | ||
| Food | Milligrams (mg) per serving | Dina rate in percent |
| Mussels are cooked | 5.8 | 252 |
| Hazelnuts, dry roasted | 1.6 | 70 |
| Brown rice, cooked, ½ cup | 1.1 | 48 |
| Oysters, boiled, 3 | 1.0 | 43 |
| Clams, boiled, | 0.9 | 39 |
| Chickpeas, cooked, ½ cup | 0.9 | 39 |
| Spinach, cooked, ½ cup | 0.8 | 35 |
| Pineapple, raw, diced, ½ cup | 0.8 | 35 |
| Soybeans, cooked, ½ cup | 0.7 | 30 |
| Bread, whole wheat, 1 slice | 0.7 | 30 |
| Oatmeal, cooked, ½ cup | 0.7 | 30 |
| Peanuts, roasted in oil, 1 oz | 0.5 | 22 |
| Tea, black, brewed, 1 cup | 0.5 | 22 |
| Lentils, cooked, ½ cup | 0.5 | 22 |
| Potatoes, flesh and skin, baked, 1 medium | 0.3 | 13 |
| White rice, long grain, cooked, ½ cup | 0.3 | 13 |
| Beans, canned, drained, washed, ½ cup | 0.3 | 13 |
| Blueberries, green, ½ cup | 0.3 | 13 |
| Sesame seeds, dried, 1 tablespoon | 0.2 | 9 |
| Kale, green, 1 cup | 0.2 | 9 |
| Black pepper, 1 gram (about ½ teaspoon) | 0.2 | 9 |
| Asparagus, cooked, ½ cup | 0.1 | 4 |
| Apple, green, with skin, 1 medium | 0.1 | 4 |
| Lettuce, romaine, green, chopped, 1 cup | 0.1 | 4 |
Dietary supplements containing manganese
Dietary supplements contain manganese in various forms, including amino acid chelates (eg, manganese bisglycinate chelate, manganese glycinate chelate, and manganese aspartate). Other forms include manganese gluconate, manganese picolinate, manganese sulfate, manganese citrate, and manganese chloride.
Not all multivitamin/mineral supplements contain manganese, but those that do usually provide between 1.0 and 4.5 mg of manganese. There are also supplements that contain only manganese or manganese with several other nutrients, and most contain between 5 and 20 mg of manganese.
Manganese intake and status
Data on manganese intake are very limited, but they suggest that most people get adequate amounts of manganese.
Manganese deficiency
Manganese deficiency is very rare in humans, and the signs and symptoms of deficiency are not well defined. Information shows that manganese deficiency can cause bone demineralization and poor growth in children; skin rashes, hair depigmentation, decreased serum cholesterol and increased alkaline phosphatase activity in men; and mood swings and increased premenstrual pain in women. Manganese deficiency can also alter lipid and carbohydrate metabolism and lead to abnormal glucose tolerance.
Manganese and health
Since manganese is a cofactor for several enzymes, low levels in the body can increase the risk of disease.
Manganese for bone health
Manganese deficiency can impair bone formation and decrease bone mineral density, while manganese supplements can increase bone mineral density and bone formation.
Scientists have investigated whether there is a link between circulating manganese levels, bone mineral density and osteoporosis in humans, but conclusive evidence is still lacking.
In one study, 10 women with osteoporosis (mean age 69.3 years) had lower serum manganese levels (20 mcg/L) than 20 women (mean age 64.5 years) who did not have osteoporosis (40 mcg/L) .
In another study of 40 postmenopausal women, serum manganese levels were positively associated with bone mineral density and negatively associated with fracture rates. Conversely, a study of 77 postmenopausal women with osteoporosis (median age 61 years) and 61 postmenopausal women without osteoporosis (median age 60 years) found no difference in red blood cell manganese levels (14.76 mcg/L in women , with osteoporosis compared to 15.54 mcg). /L in non-osteoporotic women) or plasma manganese (5.34 mcg/L in osteoporotic women vs. 5.09 mcg/L in non-osteoporotic women).
The relationship between diabetes and manganese
As a cofactor for several enzymes, manganese is involved in glucose, carbohydrate and lipid metabolism, and manganese deficiency can affect carbohydrate metabolism and lead to impaired glucose tolerance. Therefore, the researchers investigated whether manganese status affects the risk of diabetes.
Several studies have shown an association between both increased and decreased blood manganese levels and the prevalence of type 2 diabetes.
For example, in a case-control study in China of 122 adults with newly diagnosed type 2 diabetes and 429 adults without diabetes (all participants were aged 40–92 years), those with the highest plasma manganese levels (>2, 42 micrograms). /l) were 7.88 times more likely to develop diabetes than those with the third lowest level (<1.67 mcg/l).
A large case-control study in China showed a U-shaped relationship between plasma manganese levels and type 2 diabetes. This study included 1,614 adults with type 2 diabetes (mean age 52.5 years) and 1,614 adults without diabetes (mean age 54.7 years).
Compared with the average tertile of plasma manganese concentration (4.21–6.84 mcg/L), the lowest tertile (≤4.21 mcg/L) was 1.89 times more likely to be in the highest tertile (≥6.84 mcg/L l). 1.56 times more likely to develop type 2 diabetes. Other studies have found no link between blood manganese levels and the prevalence of diabetes.
Animal studies show that manganese supplements can improve glucose tolerance, reduce oxidative stress and improve endothelial dysfunction in diabetes.
Health hazards due to excessive manganese content
There is no evidence that manganese toxicity can occur from the daily diet. However, manganese toxicity has occurred in people working in occupations such as welding and mining, who were exposed to high levels of manganese due to continuous inhalation of manganese dust.
People consuming water with high levels of manganese (in some cases as high as 28 mg/L) have also developed manganese toxicity.
Manganese toxicity mainly affects the central nervous system and can cause muscle spasms, tinnitus, hearing loss and feeling unsteady when standing. Additional symptoms include insomnia, depression, delusions, anorexia, headaches, irritability, lower limb weakness, changes in mood and short-term memory, altered reaction time, and decreased hand-eye coordination.
These signs and symptoms may progress to neuromotor disturbances similar to those associated with Parkinson's disease, including gait and balance changes, tremors, and rigidity.
Iron deficiency increases the absorption of manganese, which may worsen the symptoms of toxic manganese. People with chronic liver disease have impaired biliary excretion of manganese and are more susceptible to manganese neurotoxicity and other adverse effects of excess manganese intake.
Interactions with drugs
Manganese is not known to have clinically significant drug interactions.
Manganese and healthy nutrition
Since food provides many nutrients and other health-promoting components, nutritional needs should be primarily met by high-quality, minimally processed foods. In some cases, fortified foods and nutritional supplements are helpful when one or more nutrient requirements cannot be met otherwise.
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Dietary Guidelines for Healthy Eating:
- Includes a variety of vegetables; fruits; cereals (at least half whole grains); low-fat and low-fat milk, yogurt and cheese; and oils.
Whole grains are a rich source of manganese. Some vegetables and fruits also contain manganese.
- Include a variety of protein foods, such as lean meats; poultry; eggs; seafood; beans, peas and lentils; nuts and seeds; and soy products.
Nuts, legumes and shellfish contain manganese.
- Limit foods and beverages high in added sugar, saturated fat, and sodium.
- Limits the consumption of alcoholic beverages.
- Do not exceed your daily calorie needs.
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