Except in the cases of laboratory animals the toxicity level for manganese is unknown. But anyone considering taking ten or more milligrams of the mineral daily should consult a physician to monitor the manganese serum levels in the blood. Manganese is toxic in overdose.
Workers who have inhaled manganese dust have manifested a varied assortment of symptoms, such as ataxia (muscular incoordination), loss of strength, loss of appetite, frequent headaches, mental confusion and sometimes criminal acts. They have been known to first sleep constantly and then instead suffer from insomnia. Leukopenia (low white blood cell oount) and hypochromic anemia (reduced hemoglobin in the latter stages of manganese poisoning.
In lab tests massive feedings of manganese to rats have caused negative phosphorus balances and loss of calcium in the feces: as a result, severe rickets developed. In lambs iron absorption was diminished with a high intake of manganese, and in cows tetany (low calcium in the blood and body) developed.
One of the strangest and saddest symptoms of a deficiency of manganese is a woman's loss of love for her child after birth. Although she may feel very guilty about her feelings, she may not want to nurse or hold the infant or have anything to do with it. Along with this phenomenon her nipples may become very tender, and she may experience swelling of the lymph glands. She may want to be left completely alone and may suffer crying spells. Moreover, she may be testy, arguing easily.
Some other less noticeable symptoms of a deficiency of manganese are crackling or popping bones as a person gets up to walk or a burning or gripping sensation of the arms or legs. And the eyes may become red and swollen, although the individual has not cried recently.
With a severe deficiency in a child bone growth may be stunted. An outcome of a severe deficiency in an adult may be sterility or impotence.
In addition, one kind of diabetes is being blamed in part on a deficiency of manganese because the mineral plays a very important part in the glucose cycle by helping to remove excess sugar from the blood through either oxidation or storage.
Myasthenia Gravis (a disease that attacks muscle coordination and causes loss of strength) is felt to be related to a deficiency of manganese, too, as is multiple sclerosis (a nerve degeneration disease).
As I've indicated, the only tests with manganese have been conducted on animals. One experiment that caused some flurry among the scientific community showed that manganese inhibits iron uptake. The experimenters thought that perhaps iron and manganese share a pathway, but the general consensus since then is that there exist separate pathways for manganese and iron.
The amount of manganese in the body appears to affect cholesterol levels. The mineral has been used to bring levels of cholesterol down in cases of atherosclerosis In another test regarding fat and lipid metabolism manganese was found to increase cholesterol synthesis.
Scientists have found that administrations of estradiol (a steroid produced by the ovary and having estrogenic properties) increase the level of manganese in the blood, whereupon the thyroid gland tends to accumulate the mineral. Scientists have also found that estradiol given in sufficient amounts will depress the basal metabolic rate in a guinea pig. Women taking estrogen-hormone drugs should inquire if estradiol is in the drugs and then note if they have been experiencing hypothyroid symptoms. If hypothyroidism is suspected, the doctor should be informed so that tests can prove out the assumption.
Studies have indicated that two experimental cancers are cured or markedly inhibited by manganese malate. Furthermore, in test tube experiments manganese malate changed the respiration of these cancers from anaerobic (when a cell can exist without free oxygen taken from the body) to aerobic (when a cell needs free oxygen taken from the body to live and grow). By producing this change the mineral killed both types of cancer.
It is also thought that manganese promotes production and development of blood cells in the bone marrow.
And myasthenia gravis may be related to a deficiency of manganese. With the disease nerve endings that rely on cholin and acetic acid (acetylcholine) to transmit messages are defective. If too little manganese is available to help cholin, it is possible that the nerve impulse messages will falter or not reach their intended destinations, causing muscular weakness or incoordination. „„ u>
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