Manganese: good, with caution

Manganese (Mn, atomic number 25) is an important chemical element for all living organisms. In plants, an adequate supply of manganese through water or fertilizers is essential to avoid yellowing or browning of the leaves, until they fall (with consequent risk of death of the entire plant), as well as to ensure a rich flowering and a good yield of crops.

In animals and humans, manganese plays key biological roles at various levels as a regulator of numerous enzymes involved in various ways in the metabolism of proteins, sugars and cholesterol. In addition, it is essential for the proper development of bones, for the functionality of the nervous system and for fertility and supports the activity of the body’s antioxidant systems.

On the other hand, this mineral is the clear demonstration of how important it is, when it comes to nutrition, to always keep in mind the recommendation of the ancient Latins “est modus in rebus” (Horace), that is to say that there is a measure in all things. If it is true, in fact, that taking too little manganese can create health problems on several fronts, it is equally true that not even exceeding is a good idea, since we expose ourselves to the risk of toxicity damage, especially neurological ones.

But let’s proceed in order and try to understand why this element is necessary, how much you need to take to stay healthy and efficient and where to find it.

What is manganese

Manganese is a metal widely distributed in nature especially in rocks and water, generally in the form of inorganic compounds with other elements, but also (to a lesser extent) in the air.

In the human body, this micronutrient is present in trace amounts, concentrated mainly in the bones, liver, kidneys and pancreas. In particular, it has been calculated that the body of an adult man of average height and weight contains about 10-40 mg: very little, out of 60-80 kg of total weight, but despite this it still performs absolutely necessary activities.

First of all, manganese participates as a cofactor in the activity of superoxide dismutase (SOD) present in the mitochondria of cells, one of the main enzymes responsible for detoxifying the body from free radicals and reactive oxygen species (ROS) produced mainly by energy metabolism, but also by stress associated with inflammatory and infectious diseases, physical activity, exposure to pollutants, taking drugs, etc.

Free radicals and ROS damage almost all tissues of the body, promoting inflammatory diseases, cardiovascular, neurodegenerative diseases and tumors (due to DNA alterations) and accelerating the aging process; It is therefore immediately evident that ensuring an adequate intake of a protective microelement such as manganese, with antioxidant properties similar to those of selenium, is a duty and advisable.

Manganese is also involved in the activity of several other fundamental enzymes, such as arginase, cholinesterase, phosphoglucomutase, pyruvate carboxylase, various phosphatases, peptidases and glycosyltransferases.

Through this varied and multiple activity of enzymatic modulation, manganese participates and is necessary for bone development (manganese also mediates calcium absorption), plays an important role in the metabolism of carbohydrates, amino acids and cholesterol, in gluconeogenesis (production of glucose from non-carbohydrate precursors), in collagen synthesis and therefore in the wound healing process.

Food sources

Manganese is found in fair quantities in many foods of plant origin, such as wheat germ, whole grains (wheat, wheat, rye, oats, sorghum, rice, bulgur etc.) and bran, while it is present in much smaller quantities in refined flours, since this mineral is concentrated mainly in the outer layers of the seeds.

Other good sources of manganese are legumes (especially soy), dried fruit (in particular, nuts and hazelnuts) and seeds of various types (pumpkin, sunflower, etc.), whose daily consumption is spreading considerably also in relation to the high content of other substances with high nutritional value and favorable properties for health typical of these foods (vitamins, omega-3 and omega-6 fatty acids, minerals, etc.)

The plant kingdom also provides manganese through green leafy vegetables (spinach, salads, radicchio, parsley etc.) and black tea, while it is found in smaller quantities in other vegetables.

The manganese content, on the other hand, is very low in foods of animal origin: the main sources, in this case, are oysters and liver, while other fish, white and red meat and dairy products have little effect on meeting daily needs.

What happens in case of shortage

A manganese deficiency can impair glucose tolerance, which manifests itself as a relative inability of cells to efficiently absorb and use blood sugar, resulting in increased blood sugar and increased risk of developing diabetes.

Other possible disorders and alterations related to insufficient manganese intake include bone depletion, muscle weakness and tendon.

Recommended doses

Manganese must never be missing in the daily diet, neither of children nor adults, but any nutritional supplements of this element, in addition to food, must be implemented with some caution and, especially in pediatric age, under medical supervision, after having ascertained the actual need with some laboratory tests.

According to the Italian Society of Human Nutrition (SINU) the levels of adequate daily intake for manganese correspond to:

From 18 years onwards the dosage remains the same unless pathologies occur that can reduce the need (mainly, liver and kidney failure).

The need for manganese can instead increase if calcium and phosphorus supplements are taken in order to support bone metabolism, since these three elements are used together. In any case, at no time in life should manganese be taken beyond the safe threshold of about 11 mg / day.

Intoxication and toxicity

Manganese poisoning is a rare occurrence. Toxicity caused by high dietary intake has never been verified. Almost exclusively those involved in the extraction and refining of this mineral, in the production of metals and metal components of various types (in particular, materials and articles made of iron, steel and other alloys including molybdenum and aluminium), electric batteries and catalysts, or used in the chemical industry (potassium permanganate) are affected. It is a powerful disinfectant used in the medical field), in glass recycling plants (where manganese is used as a bleaching) or in the production of fertilizers for agriculture.

Another possible source of manganese poisoning is environmental and linked to the consumption of water that contains excessive amounts, due to the composition of the groundwater rocks that cross before arriving at the aqueducts and being used by man. In this regard, it should be noted that, in Italy, the maximum quantity of manganese allowed by law in drinking water is 50 mg / liter (Legislative Decree no. 31 of 2 February 2001), against 200 mg / liter of sodium and 250 mg / liter of chlorine, in the form of chloride: if the water of a given geographical area contains more it must be properly treated before food use.

Symptoms of manganese toxicity observed following excessive occupational or environmental exposure include loss of appetite, memorization difficulties, headaches, neurological deficits and muscle control disorders similar to those of Parkinson’s disease (tremors, contractures, difficulty moving, etc.).

It has also been observed that prolonged exposure to manganese, interfering with iron absorption, can induce deficiency of this micronutrient and consequent iron deficiency anemia; In people with severely impaired liver or kidney function, persistent excess manganese can cause schizophrenia-like symptoms, tremors, and hypertension.

Interactions of manganese with foods, drugs and supplements

Those who take supplements containing manganese should be aware that this micronutrient can interact with certain foods, medications and nutritional supplements or be influenced by the latter in terms of absorption, metabolism and elimination.

With regard to food, it should be remembered that a low-fat diet can reduce the body’s ability to absorb manganese, whilesupplementation with milk proteins (obtained through a greater consumption of dairy products or specific protein supplements) tends to increase intestinal absorption.

Even phytic acid, contained in many foods of plant origin (such as cereals, dried fruits and legumes) can slightly reduce the absorption of manganese, which should therefore be taken at least 2 hours before consuming foods rich in phytates.

With regard to drugs, some antacids, laxatives and tetracycline can reduce the absorption of manganese.

With regard to the use of supplements containing calcium, iron and magnesium, it should be considered that these essential elements can reduce the absorption of manganese present in food, water or supplements. Even in these cases, it is advisable to take the manganese supplement at least 2 hours before ingesting supplements or foods rich in these substances.