Dolomite

Dolomite as a Dietary Supplement: A Comprehensive Reference

1. Identity, Chemical Composition, and Natural Source

Dolomite is a mineral and a rock-forming mineral composed of calcium magnesium carbonate with the chemical formula CaMg(CO₃)₂. It is a double carbonate, having an alternating structural arrangement of calcium and magnesium ions. The term dolomite refers to both the calcium-magnesium carbonate mineral and to the sedimentary rock formed predominantly of this mineral.

As a supplement material, dolomite is constituted of approximately 60% calcium carbonate and 40% magnesium carbonate; however, it may also contain heavy metals such as lead. In terms of elemental yield, nutrition-grade powder is standardised to provide approximately 21% elemental calcium and 13% elemental magnesium, offering a balanced mineral profile for various food and supplement applications. The mineral dolomite contains equimolar amounts of calcium and magnesium, with a weight ratio of Ca to Mg of approximately 2:1.

The mineral dolomite crystallizes in the trigonal-rhombohedral system and forms white, tan, gray, or pink crystals. It forms in various geological settings, typically through a process called dolomitization, which involves the alteration of limestone by magnesium-rich fluids; the magnesium ions replace some of the calcium ions in the mineral structure, leading to the formation of dolomite. Most rocks rich in dolomite were originally deposited as calcium carbonate muds that were post-depositionally altered by magnesium-rich pore water.

Dolomite accounts for about ten percent of all sedimentary rock, including much that would have been produced near the surface of the Earth. It has a wide global distribution and is found in sedimentary basins across continents, including in the Dolomite Mountains of northern Italy, large deposits in the United States and Canada, deposits in Madhya Pradesh, Chhattisgarh, Odisha, and Rajasthan in India, and significant deposits in China and Australia.

1.1 Nomenclature and Terminology

The term "dolostone" was introduced in 1948 to avoid confusion between the mineral and the rock; however, its usage is controversial because the name dolomite was first applied to the rock during the late 18th century and thus has technical precedence. The use of the term dolostone is not recommended by the Glossary of Geology published by the American Geological Institute. In old United States Geological Survey (USGS) publications, dolomite was referred to as "magnesian limestone," a term now reserved for magnesium-deficient dolomites or magnesium-rich limestones.

1.2 Common Dosage Forms and Preparations

Dolomite has long been used as a source of calcium and magnesium for animal feeds, and is now available in a number of dosage forms including tablets and chewable wafers as dietary supplements. It is also sold commercially as a powder. Food-grade dolomite is also added to desalinated drinking water as a source of magnesium; while ground and surface water for drinking contains sufficient magnesium for human health, some regions depend on desalinated water for drinking, and in such cases dolomite is used as an economical and effective indirect supplement.

2. Historical Discovery and Traditional Use

2.1 Scientific Discovery

As stated by Nicolas-Théodore de Saussure, the mineral dolomite was probably first described by Carl Linnaeus in 1768. In 1791, it was described as a rock by the French naturalist and geologist Déodat Gratet de Dolomieu (1750–1801), first in buildings of the old city of Rome, and later as samples collected in the Tyrolean Alps. Nicolas-Théodore de Saussure first named the mineral (after Dolomieu) in March 1792.

2.2 Agricultural and Animal Feed Use

Dolomite has long been used as a source of calcium and magnesium for animal feeds. Its use in agriculture as a soil amendment to correct acidity also has an extended history. In horticulture, dolomite may be added to soils and potting mixes to lower their acidity.

2.3 Use as a Human Mineral Supplement

In the past, given its chemical composition, dolomite used to be prescribed as a calcium and magnesium supplement; however, due to contamination with toxic elements such as lead and mercury, and the availability of better supplementary forms of calcium and magnesium compounds, it is no longer used as a therapeutic agent. No information exists to indicate that dolomite has any other therapeutic applications in human diseases.

The use of dolomite as a human supplement became a notable commercial practice in the latter half of the twentieth century, when calcium supplementation gained wider medical endorsement, particularly for osteoporosis prevention. In 1981, the FDA cautioned the public to limit the intake of calcium supplements made from dolomite or bone meal because of potentially hazardous lead levels. Additional studies showed that other calcium supplements, such as carbonates and various chelates, may also contain hazardous amounts of lead.

3. Chemical Constituents and Active Compounds

3.1 Primary Mineral Constituents

The two primary active constituents of dolomite as a dietary supplement are its constituent elements: calcium and magnesium, delivered in carbonate salt form. Dolomite is a type of limestone rich in magnesium carbonate and calcium carbonate; it also contains several other minerals.

Calcium carbonate (CaCO₃) comprises the majority of the mineral by weight. In the body, the carbonate counterion is metabolized to bicarbonate, and calcium is liberated for physiological use. Calcium is a macromineral essential for skeletal mineralisation, neuromuscular transmission, hormonal secretion, vascular contraction, and intracellular signalling.

Magnesium carbonate (MgCO₃) constitutes the remainder. Magnesium is a cofactor in over 300 enzymatic systems, including those involved in protein synthesis, muscle and nerve function, blood glucose regulation, and blood pressure regulation.

3.2 Trace Contaminants

Dolomite is possibly unsafe when taken by mouth, as dolomite supplements may be contaminated with heavy metals including aluminum, arsenic, lead, mercury, and nickel. Dolomite supplements have been found to have higher rates of lead contamination than other calcium sources. Calcium supplements made from sedimentary rocks (including dolomite and chalk) have also been reported to have higher polonium levels than organic calcium compounds.

Deposits of carbonate rock like limestone and dolomite may also contain tremolite asbestos, a recognised occupational and environmental hazard.

3.3 Mechanisms of Action of the Constituent Minerals

The putative effects of dolomite as a supplement are attributable entirely to the properties of its constituent calcium and magnesium ions, not to any unique or proprietary action of the dolomite mineral matrix itself.

Calcium in the body functions primarily in the mineralisation and maintenance of bone and tooth density as hydroxyapatite [Ca₁₀(PO₄)₆(OH)₂], and in signal transduction, muscle contraction, and blood coagulation. Parathyroid hormone (PTH), calcitonin, and 1,25-dihydroxyvitamin D₃ regulate serum calcium concentrations within a tight physiological range.

Magnesium influences bone metabolism both directly and indirectly. Magnesium can directly affect bone cell function as well as influence hydroxyapatite crystal formation and growth; furthermore, epidemiological studies have provided a major link associating dietary magnesium inadequacy with osteoporosis.

Some researchers have suggested that the effects of calcium supplementation alone on bone status were weaker than when supplements were combined with other minerals and phytochemicals, making it important to identify trace elements that may augment calcium's positive effects on bone.

4. Scientific Evidence by Area of Application

4.1 Bone Metabolism and Osteoporosis

This is the primary area in which dolomite has been investigated, owing to its calcium and magnesium content. However, the evidence base is almost entirely preclinical (animal studies), with no published controlled clinical trials specifically testing dolomite supplementation in humans for bone outcomes.

Animal studies: One published animal study examined the effects of daily supplementation with dolomite on calcium metabolism in ovariectomized (OVX) rats—a standard model of post-menopausal bone loss. Dolomite was administered daily for 9 weeks, with the same amount of magnesium chloride given as a positive control. Histological examination revealed that ovariectomy decreased trabecular bone and increased adipose tissues in the femoral metaphysis; dolomite or magnesium supplementation failed to improve these bone histological features. Calcium content in the femora was decreased in OVX rats, and neither calcium nor magnesium content in the femora was significantly increased by dolomite or magnesium administration.

In a second rodent study, dolomite repaired bone damage more effectively than the negative control; however, dolomite was less effective than the positive control (bovine bone).

Clinical evidence: Research reveals no clinical data regarding the use of dolomite as a magnesium and calcium supplement, and there are no recent clinical studies of dolomite to provide a basis for dosage recommendations. The effect of magnesium supplementation on bone metabolism in patients with osteoporosis remains a matter of controversy, a debate that extends to dolomite as a magnesium vehicle.

Overall evidence strength: Weak to absent. Preclinical data are mixed, and there are no human clinical trials. No clinical efficacy claims for dolomite supplementation in bone health can currently be supported by the evidence.

4.2 Calcium and Magnesium Repletion

People use dolomite as a source of calcium and magnesium, but there is no good scientific evidence to support this use. In animal models, minerals from dolomite are well absorbed, but human bioavailability data specific to dolomite (as opposed to refined calcium and magnesium salts) are not established in published clinical literature.

There are three main types of calcium supplements used clinically: calcium carbonate, calcium citrate, and other forms such as calcium gluconate and calcium lactate. Calcium carbonate and calcium citrate contain more calcium and show more benefits in the research literature than dolomite-derived preparations.

4.3 Electrolyte Balance and Alkalising Action

Dolomite has been marketed with claims related to electrolyte support and body alkalisation. These claims derive from the carbonate nature of both its calcium and magnesium salts, which can act as buffers. However, no information exists to indicate that dolomite has any therapeutic applications in human diseases beyond being a vehicle for calcium and magnesium delivery.

4.4 Antiviral Activity

One preliminary laboratory investigation cited in the literature (Yamana et al., J. Vet. Med. Sci., 2007) examined heated and hydrated dolomite for antiviral activity. This work is preliminary veterinary science and provides no basis for claims regarding human antiviral benefit.

4.5 Drinking Water Remineralisation

This is the best-supported application of dolomite in a health-relevant context. Dolomite remineralisation has a marked advantage because this mineral is a double salt composed of CaCO₃ and MgCO₃, and its dissolution can provide both calcium and magnesium ions in a single process. The Kingdom of Saudi Arabia is dependent on desalinated water which has a low magnesium content; magnesium in drinking water is considered important for cardiovascular health, and it is anticipated that the World Health Organization will introduce minimum magnesium recommendations. Replacement of limestone with dolomite in existing contactors in two commercial desalination plants was effective in raising magnesium concentrations in the produced water by 2.4 ± 0.5 ppm (Shoaibah, Multi-Stage Flash desalination) and 2.9 ± 0.2 ppm (Al Khobar, Reverse Osmosis desalination), sufficient to lift total Mg above the Saudi Arabian guideline value of 5 ppm.

In food-grade GRAS-notified contexts, dolomite is used to enhance the levels of calcium, magnesium, and carbonate in water to improve the taste of purified water beverages. Remineralisation of demineralised water using calcite contactors is achieved by passing a stream of acidified water through a bed of calcite chips; these chips are usually limestone or marble, but in some cases dolomite, chalk, precipitated calcium carbonate, or even muscle shells are used.

5. Body Systems Associated with Dolomite Supplementation

5.1 Skeletal System

As a combined source of calcium and magnesium, dolomite is primarily associated with claims of skeletal support. Calcium is the primary structural mineral of bone, while magnesium influences hydroxyapatite crystal formation and bone cell function. However, as detailed above, direct evidence from human trials is absent.

5.2 Neuromuscular System

Both calcium and magnesium are essential electrolytes for neuromuscular function. Calcium mediates neurotransmitter release and muscle contraction; magnesium acts as a physiological antagonist to calcium at numerous receptor sites and regulates nerve impulse transmission.

5.3 Cardiovascular System

People with heart block should avoid dolomite. Dolomite is a source of magnesium, and extra magnesium is not appropriate for people with heart block. The cardiovascular relevance of dolomite-derived magnesium in desalinated drinking water is an active area of public health research, though this pertains to population-level water quality rather than individual supplementation.

5.4 Renal System

Extra magnesium and calcium can harm people with kidney disease. Dolomite is a source of both of these minerals, and its use should be avoided in those with serious kidney problems.

5.5 Endocrine (Parathyroid) System

The parathyroid gland releases a hormone that regulates the amount of calcium in the blood. If this gland is either too active (hyperparathyroidism) or underactive (hypoparathyroidism), the calcium balance is disturbed; taking dolomite, as a source of calcium, can make this imbalance worse.

5.6 Respiratory System (Occupational Exposure)

This is an area where dolomite has documented risks, albeit from inhalation rather than ingestion. Although dolomite is classified as a relatively non-toxic, nuisance dust, little information exists as to its potential to produce respiratory disorders following occupational exposure; one study aimed to evaluate the possible effects of heavy inhalation exposure on the prevalence of respiratory symptoms, functional impairments, and radiographic abnormalities of the lungs. The study population consisted of 39 exposed subjects engaged in digging and excavating activities for building a local dam, and 40 healthy non-exposed employees as a referent group. Atmospheric concentrations of dolomite dust exceeded current permissible levels, and exposed workers had significantly higher prevalence rates of respiratory symptoms than their referent counterparts (p<0.05). Decrements were also noted in most parameters of pulmonary function in exposed workers, although the difference was only significant for the FEV1/FVC ratio (p<0.05); no significant differences were noted between exposed and referent subjects as regards chest radiographs.

A separate study in Swedish dolomite workers examined tremolite asbestos co-contamination. Deposits of carbonate rock like limestone and dolomite may contain tremolite asbestos; that study assessed the exposure to tremolite asbestos and the respiratory health of Swedish dolomite workers. Dolomite dust concentrations were moderate (median 2.8 mg/m³) and tremolite asbestos concentrations were generally below the limit of detection (<0.03 fibres/ml) at that particular site.

6. Dosage Forms and Reported Dosages

Dolomite is available in a number of dosage forms including tablets and chewable wafers as dietary supplements. It is also marketed as a bulk powder.

Research reveals no clinical data regarding the use of dolomite as a magnesium and calcium supplement, and there are no recent clinical studies of dolomite to provide a basis for dosage recommendations. There is not enough reliable information to know what an appropriate dose of dolomite might be. Natural products are not always necessarily safe, and dosages can be important.

The following dosage information comes from product and preclinical study contexts only, not from established clinical guidelines:

• One commercial capsule product delivers 500 mg of dolomite per capsule, providing 110 mg of calcium and 60 mg of magnesium.
• Population-level intake data from Bailey et al. (2011) reported average total intakes from foods and supplements of magnesium to be 449 mg for men and 387 mg for women, and average total intakes of calcium to be 1,319 mg for men and 1,331 mg for women.
• Animal studies (Mizoguchi et al., 2005, J. Bone Miner. Metab.) administered dolomite daily to ovariectomized rats for 9 weeks; the dosing parameters are not directly translatable to human supplementation guidance.

Excessive magnesium intake from the intended use of dolomite is difficult if not impossible to achieve through food use, and too much magnesium from food does not pose a safety risk in healthy individuals because the kidneys eliminate excess amounts in the urine. However, high doses of magnesium from dietary supplements or medications often result in diarrhea that can be accompanied by nausea and abdominal discomfort.

7. Safety Considerations

7.1 Heavy Metal Contamination: The Principal Safety Concern

The dominant, well-documented safety concern for dolomite as a supplement is heavy metal contamination, particularly lead. This concern predates and supersedes questions about efficacy.

In 1981, the FDA cautioned the public to limit the intake of calcium supplements made from dolomite or bone meal because of potentially hazardous lead levels. This concern prompted a series of subsequent analytical studies.

In a peer-reviewed study published in Environmental Health Perspectives in 2000, Scelfo and Flegal analysed 136 brands of calcium supplements purchased in 1996. The lead content of 136 brands of supplements was determined; the calcium in the products was derived from natural sources (bonemeal, dolomite, or oyster shell) or was synthesised and/or refined (chelated and nonchelated calcium). The lead levels measured in the supplements ranged from 0.03 µg/g to 8.83 µg/g; daily lead ingestion rates revealed that about 25% of the products exceeded the FDA's "provisional" total tolerable daily intake of lead for children aged 6 years and under.

A separate JAMA study (Ross et al., 2000) found that substantial quantities of lead have been reported in some over-the-counter calcium supplement preparations, including not only bonemeal and dolomite, but also over-the-counter natural and refined calcium carbonate formulations; despite increasingly stringent limits of lead exposure, many calcium supplement formulations contain lead and thereby may pose an easily avoidable public health concern.

The ongoing use of contaminated products, especially dolomite and bonemeal, can have serious neurologic, gastrointestinal, cutaneous, and other systemic consequences. Dolomite preparations contaminated with heavy metals may lead to toxicities with long-term use.

A 2006 study by Mattos et al. (Food Additives and Contaminants) found that dolomite supplements had higher rates of lead contamination than other calcium sources.

When purchasing calcium supplements, products marked as purified (especially those made from dolomite, bone meal, or oyster shells) or those containing the USP (United States Pharmacopoeia) symbol are considered the safest.

7.2 Gastrointestinal Effects

Dolomite may cause stomach irritation, constipation, nausea, vomiting, and diarrhea. Dolomite should not be taken in large amounts for long periods, or in combination with other calcium or magnesium supplements.

7.3 Specific Vulnerable Populations

Pregnancy and lactation: Dolomite is possibly unsafe to use while pregnant or breast-feeding because of the risk of heavy metal contamination.

Children: Dolomite is possibly unsafe for children when taken by mouth. Children are more sensitive than adults to contaminants such as lead.

Individuals with heart block: Dolomite should be avoided in people with heart block, as it is a source of magnesium and extra magnesium is not appropriate for people with this condition.

Individuals with kidney disease: Extra magnesium and calcium can harm people with kidney disease; dolomite is a source of both of these minerals, and use should be avoided in those with serious kidney problems.

Sarcoidosis: Sarcoidosis increases the risk of absorbing too much calcium; dolomite should not be taken in this condition.

Parathyroid disorders: If the parathyroid gland is either too active (hyperparathyroidism) or underactive (hypoparathyroidism), the calcium balance is disturbed, and taking dolomite as a source of calcium can make the balance even worse.

7.4 Occupational Respiratory Risk

Dolomite dust may cause respiratory symptoms including cough, phlegm, wheezing, productive cough, and shortness of breath, especially among exposed workers. The main occupational hazard in dolomite processing is dust; the chemical is classified as a relatively harmless, nuisance dust with a threshold limit value of 10 mg/m³ (ACGIH) or 15 mg/m³ (OSHA).

7.5 Regulatory Standing

In the United States, dolomite is the subject of FDA GRAS Notice 806, submitted for the specific use of remineralising purified water beverages. In this context, dolomite is used to enhance the levels of calcium, magnesium, and carbonate in water to improve the taste of purified water beverages, as part of a remineralisation process. This GRAS status is specific to the water-treatment application and does not constitute a general endorsement of dolomite as a direct dietary supplement.

8. Drug Interactions

The interactions associated with dolomite are those of its constituent calcium and magnesium ions. The following are reported in clinical pharmacology references:

• Tetracycline antibiotics: Tetracycline interacts with divalent ions such as calcium and magnesium, forming a relatively stable and poorly absorbed chelate, preventing absorption of the antibiotic; this interaction may reduce or even abolish the therapeutic effect of the antibiotic. To avoid this interaction, these drugs should be taken at least 2 hours before or 4 to 6 hours after dolomite.
• Quinolone (fluoroquinolone) antibiotics: The minerals in dolomite can bind to quinolone antibiotics in the gut, decreasing how much quinolones the body absorbs. To avoid this interaction, these drugs should be taken at least 2 hours before or 4 to 6 hours after dolomite.
• Bisphosphonates: Dolomite can decrease how much bisphosphonate the body absorbs; taking dolomite along with bisphosphonates can decrease the effects of bisphosphonates. To avoid this interaction, bisphosphonates should be taken at least 30 minutes before dolomite or later in the day.
• Levothyroxine: Dolomite can decrease how much levothyroxine the body absorbs. This interaction is attributed to calcium's ability to bind levothyroxine in the gastrointestinal tract.
• Potassium-sparing diuretics: Dolomite contains magnesium, and some water pills (potassium-sparing diuretics) can increase magnesium levels in the body; taking such diuretics along with dolomite might increase magnesium levels too much.
• Estrogen: Estrogen helps the body absorb calcium; taking estrogen in combination with large amounts of calcium could increase the amount of calcium in the body too much.
• Thiazide diuretics: Thiazide diuretics can cause increased calcium reabsorption in the distal tubules of the kidneys, which contributes to hypercalcaemia. An additional cause of hypercalcaemia is excess vitamin D intake, which increases calcium absorption in the gut; due to the retention of calcium in the body, metabolic alkalosis may develop.

9. Summary of Evidence Strength

People use dolomite as a source of calcium and magnesium, but there is no good scientific evidence to support this use, and it might be unsafe. The overall evidence profile for dolomite as a dietary supplement is as follows:

• Mineral delivery (calcium/magnesium): Dolomite is a chemically valid source of both minerals; animal absorption data are acceptable, but human clinical trials comparing dolomite to purified calcium or magnesium preparations are absent.
• Bone health: Animal studies show inconsistent, largely negative results for bone histological outcomes. No human trials exist.
• Safety: Well-documented concerns about heavy metal contamination, particularly lead, from multiple independent peer-reviewed studies and an FDA advisory (1981), represent a substantiated risk. The occupational respiratory hazard from dust inhalation is also supported by peer-reviewed evidence.
• Water remineralisation: The application of food-grade dolomite in desalinated drinking water treatment is technically validated and commercially deployed, with FDA GRAS notification and published pilot data.

References

• Neghab M, et al. Respiratory disorders associated with heavy inhalation exposure to dolomite dust. Iran Red Crescent Med J. 2012;14(9):549–57. PMC3482327
• Selden AI, et al. Exposure to tremolite asbestos and respiratory health in Swedish dolomite workers. Occup Environ Med. 2001;58(10):670–677. PMC1740050
• Bourgoin BP, et al. Lead content in 70 brands of dietary calcium supplements. Am J Public Health. 1993;83(8):1155–60. PMC1695147
• Scelfo GM, Flegal AR. Lead in calcium supplements. Environ Health Perspect. 2000;108(4):309–319. PMC1638001
• Ross EA, et al. Lead content of calcium supplements. JAMA. 2000;284(11):1425–1429. PubMed 10989406
• Mizoguchi T, et al. Dolomite supplementation improves bone metabolism through modulation of calcium-regulating hormone secretion in ovariectomized rats. J Bone Miner Metab. 2005;23(2):140–146.
• Drugs.com Natural Product Database: Dolomite. Uses, Benefits & Dosage (updated January 2026).
• WebMD Natural Medicines Database: Dolomite — Overview, Uses, Side Effects, Precautions, Interactions, Dosing.
• RxList: Dolomite Health Benefits, Side Effects, Uses, Dose & Precautions.
• U.S. Food and Drug Administration. GRAS Notice No. GRN 806 for Dolomite (December 2019).
• Go Ask Alice! (Columbia University): Can I use dolomite as a nutritional supplement? (2015).
• Discover Water (Springer Nature): Dolomite for supplementation of desalinated drinking water in Saudi Arabia with magnesium, calcium, and hydrogen carbonate ions (2025).
• ScienceDirect: Theoretical and experimental study of micronized dolomite dissolution (2024).
• PubMed 26680713: Improving Drinking Water Quality by Remineralisation (2015).
• Wikipedia: Dolomite (mineral) — historical discovery, chemical composition, and geological properties.
• Encyclopaedia Britannica: Dolomite — Formation, Structure, Properties, Uses, & Facts.
• Geology.com: Dolomite Mineral — Uses and Properties.
• Encyclopedia.com: Dolomites — including section on calcium supplement lead contamination and FDA advisory.
• PMC6835757: Prevalence of Medication-Dietary Supplement Combined Use and Associated Factors — mineral-drug interactions including calcium, magnesium, and tetracycline.
• JAMA Network (2000): Lead in Calcium Supplements — Roberts HJ letter re: dolomite and bonemeal contamination. JAMA. 2000;284(24):3126–7.