Description
Dolomite, named for the French geologist D.G. Dolomieu, is a mineral containing calcium and magnesium carbonate, as well as trace heavy metals. It is a double salt made up of approximately 60% calcium carbonate (equivalent to 24% calcium) and 40% magnesium carbonate (equivalent to 12% magnesium). Dolomite is also known as magnesium limestone and earlier was called compound-spar, bitter-spar, rhomb-spar and pearl-spar. The Dolomites, a mountain region in the South Tyrolese Alps, are named for the presence of dolomite in the mountains.
Dolomite was at one time a popular nutritional supplement for calcium and magnesium. It is still marketed as a nutritional supplement, but is no longer popular. The reason for this is that in the early 1980s analysis of dolomite nutritional supplements revealed them to contain substantial amounts of lead, as well as other toxic elements, such as mercury, arsenic and cadmium. In addition, much better supplementary forms of calcium and magnesium are available. Dolomite is still used in several parts of the world as a liming agent, to raise the pH of the soil, and as a fertilizer to maintain soil magnesium levels. It is also used to make magnesia, which has medical applications.
Actions & Pharmacology
Actions
Dolomite is a delivery form of calcium and magnesium.
Mechanism of Action
See Calcium and Magnesium.
Pharmacokinetics
See Calcium and Magnesium. Noteworthy is that magnesium from magnesium carbonate is more poorly absorbed than it is from most other magnesium supplements.
Indications & Usage
Dolomite is no longer recommended as a calcium or magnesium source because it may be contaminated with toxic metals such as lead.
Overdosage
There are no known reports of overdosage of dolomite.
Dosage
No recommended dose.
Literature
Boulos FM, von Smolinski A. Alert to users of calcium supplements as antihypertensive agents due to trace mineral contaminants. Am J Hypterten. 1988; 1(3 Pt 3):137S-142S.Bourquin BP, Evans DR, Cornett JR, et al. Lead content of 70 brands of dietary calcium supplements. Am J Public Health. 1993; 83:1155-1160.Roberts HJ. Potential toxicity due to dolomite and bone meal. South Med J. 1983; 76:556-559.Whiting SJ. Safety of some calcium supplements questioned. Nutr Rev. 1884; 52:95-97.Research & Summary
Several studies have revealed significant toxic metal contamination of many randomly selected and analyzed dolomite supplements (the same is true of some other ""natural'' calcium sources, e.g., bonemeal and ""oyster shell'' or ""natural source'' calcium carbonate). In one study of randomly selected dolomite tablets, aluminum, arsenic, zinc, cadmium and lead were among the metals found. The researchers cautioned that ""these trace metals could pose health risks to the public such as lead poisoning, dementia and hypertension due to cadmium. Also, zinc can potentiate cadmium-hypertensive effects.''
Another researcher has pointed out that ""physicians must consider the possibility of unrecognized self-poisoning from the consumption of such substances, especially in the context of unexplained neurologic, gastrointestinal, cutaneous and hematologic disorders.''
Contraindications, Precautions & Adverse Reactions
Contraindications
Those with hypercalcemia should not take calcium supplements. Conditions that cause hypercalcemia include hyperparathyroidism, hypervitaminosis D, some granulomatous diseases, sarcoidosis and cancer.
Those with renal failure and high-grade atrioventricular blocks should not take magnesium supplements.
Precautions
Dolomite is no longer recommended as a calcium and magnesium supplement because of possible presence of toxic metals, such as lead, Children are especially sensitive to the effects of lead. Children, pregnant women and nursing mothers should absolutely avoid dolomite.
Interactions
See Calcium and Magnesium for adverse reactions of supplements containing these minerals. Prolonged use of dolomite containing toxic elements, such as lead, may cause the typical toxic effects of those substances.
