Premise
In the previous article we described the main characteristics of manganese, analyzing its beneficial effects within the organism and the different fields of technological and biological application. In this concluding discussion we will study the importance of manganese and its potential toxicity when taken in excessive doses. Finally, a mention must be made of foods rich in this precious mineral and interactions with other natural and synthetic substances.
Deficiency symptoms
Fortunately, manganese deficiency symptoms, not so pronounced, are rarely found in man; when present, man can complain of myasthenia gravis and ataxia. It is hypothesized that a deficiency of this trace element can cause damage to reproductive capacity, development, bone and cartilage formation, fat and carbohydrate metabolism, with possible consequences on diabetes and hypercholestrolemia. [adapted from Nutrition in naturopathy, by L. Pennisi]
Manganese toxicity
If on the one hand the lack of manganese in the body does not trigger unquestionably proven serious effects, on the other hand the excess of this mineral can have serious repercussions on human health. Tant "is that we are talking about real chronic manganese poisoning: generally, intoxication occurs by prolonged inhalation of smoke and / or dust of the trace element. The maximum limit beyond which manganese is defined as toxic is estimated to be around 5mg / m3-1 mg / m3.
The damage deriving from manganese poisoning mostly involves the central nervous system: poisoning can generate permanent damage. Furthermore, it is believed that manganese and its derivatives are potentially carcinogenic substances.
Following frequent and prolonged exposure to manganese fumes (typical danger of the metalworking industry) numerous cases of Parkinson's disease have been highlighted: in this regard, manganese is included in the list of toxic and dangerous substances, drawn up by OSHA (Occupational Safety and Health Administration).
A variety of symptoms have been recorded following manganese poisoning, including weakness, leg cramps, drowsiness, paralysis, languor, impotence, emotional disturbances and irritability.
Effects such as hallucinations, tendency to violence, irritability are not uncommon in miners: for this reason the intoxication is also known by the term "manganese madness"
Manganese and dosages
The recommended daily requirements (RDA) of manganese are estimated between 2 and 4 mg: this quantity has caused great confusion among scholars, since for some - given that the real (and not hypothetical) absorption of the mineral is rather poor - the dosage appears to be too low. For some, the RDA for manganese should be around 20 mg / day, or even 50 mg on therapy; in any case, 2 or 3 mg per day of manganese does not seem to trigger effects of deficiency or excess and the value 0.74 mg / day constitutes the minimum daily requirement.
It should be remembered that manganese is almost completely eliminated through the biliary tract, although the entero-hepatic circulation reduces its losses.
In the urine, manganese is found only in very low percentages.
Before we mentioned a poor absorption of the mineral: it is believed possible that the manganese coming from the diet is absorbed in a variable percentage from 5 to 10%, even if - it must be emphasized - the "efficiency of absorption" is considered greater in the case of poor nutritional intake. [taken from www.valori-alimenti.com]
Food sources of manganese include (doses referred to 100 grams of food):
- Tea 133 mg
- Ginger 33.3 mg
- Cloves 30 mg
- Saffron 28.4 mg
- Mint (dried drug) 11.4 mg
Interactions
It is thought possible that the intake of iron-containing foods or supplements may hinder the absorption of manganese, since both use transferrin as an ideal blood transport molecule. The same goes for calcium and phosphorus, minerals that can interact with manganese limiting its absorption.
The absorption of manganese in subjects suffering from severe hypertension can be hindered, since the trace element in question is considered a hypertensive mineral.
The use of the contraceptive pill can also limit the absorption of manganese.
Other articles on "Manganese: deficiency, excess and intake doses"
- Manganese
- Manganese in brief: summary scheme
