Removal of Heavy Metals from the Body

by Lauren O'Brien

Metallothionein is the body's primary defense against heavy metals entering the body. MT proteins have an affinity for mercury, copper, cadmium, silver, zinc and lead. MT-I and MT-II proteins are present in high concentration in the intestinal area of the G.I. tract and form a barrier against lead, mercury etc. Under normal conditions heavy metals are sequestered in mucosa MT and sloughed off every 5-10 days and passed out through the stool. When the MT defense is disabled toxic metals can leak from the intestinal walls and enter the bloodstream. Toxic metals left in the intestines may bind with sulfhydryl groups and disable important digestive enzymes. High concentrations of MT proteins are also found in the brain, liver and kidney and it has been proposed that they are probably present in large quantities along the blood-brain barrier. Heavy metal toxicity left unchecked in the body may result in impaired hyppocampus function, disruption of the calcium channels, altered concentrations of neurotransmitters, impairment of the myelin sheath, liver damage and kidney damage.

Copper and zinc regulation:

Metallothionein plays a key role in the regulation of copper levels throughout the body. Copper absorption is inversely related to the amount of MT-I and MT-II proteins present in the gut. (the smaller the amount of MT proteins present, the greater the amount of copper absorbed) Most copper is bound to cerloplasm, but MT proteins can serve as a temporary storage site in the presence of excessive amounts of copper. Once the MT proteins bind copper, they are unable to bind zinc and become disabled. In Wilson's disease, ( Wilson's disease is a rare inherited disease characterized by toxic deposits of copper throughout the body), researchers have shown that a persistent copper toxicity can overload and disable MT proteins. The leading Wilson's disease therapy involves removal of excessive copper followed by restoration of normal zinc levels. Dr. W. Walsh proposes that the same treatment may be affective in treating autism.

Metallothionein and the G.I. tract:

MT proteins are found in the highest concentrations in the G.I. system. MT-IV is present in high concentration on the tongue. MT deficiency may result in a zinc deficiency in the tongue contributing to abnormal sensitivity to taste and texture. MT-IV is also found in high concentrations in the stomach. The primary roles MT proteins play in the stomach include production of hydrochloric acid, donation of zinc atoms for digestive enzymes and protection against stomach inflammation. Lowered production of hydrochloric acid may result in a decreased secretin response by the pancreas due to the poorly chummed food entering from the stomach area.

MT proteins in the intestinal system donate zinc for the synthesis of the enzymes needed to breakdown casein, gluten and other proteins. Zinc deficiency may also be responsible for severe food allergies. MT proteins are the primary defense against intestinal inflammation and diarrhea. MT proteins kill candida and prevent yeast overgrowth.

Metallothionein and Immune Function:

MT proteins are the primary vehicle for delivering zinc to cells. Zinc is found in over 200 enzymes in the body, and is part of more enzymatic reactions than any other mineral. It is needed for the regulation of hormones including the sex hormones, growth hormone and thymic hormones. MT proteins perform the function of immunomodulators as well.

MT plays an important role in the regulation of humoral and cellular immunity. Individuals with an impaired MT function exhibit a decreased amount of circulating T-cells (may be due to zinc deficiency) MT proteins also act as scavengers of free radicals that are not bound.