Calcium carbonate

What is Calcium Carbonate

Calcium carbonate is a well-known food supplement containing 40% calcium, a precious bone-friendly mineral; it is also used as an antacid drug to relieve heartburn and acid juice regurgitation.

Still in the field of food supplements, calcium carbonate is used as an anti-aggregating agent capable of giving compactness to tablets.

Use as a calcium supplement

One of the main advantages of calcium carbonate is undoubtedly the particularly low cost, especially when compared to other calcium salts.

In every gram of product we find 400 mg of calcium, while in a similar quantity of calcium citrate only 210 are present. The bioavailability of these two salts is superimposable on a full stomach, while citrate is more easily absorbed on an empty stomach. Therefore calcium carbonate supplements should be taken at the same time as meals or shortly after their end. To learn more, we recommend reading the article dedicated to calcium citrate, with bibliographical references when stated in this chapter.

Use as an antacid

CaCO ₃ + 2HCl -> CaCl ₂ + H ₂ O + CO ₂ . As underlined by this formula, after ingestion, calcium carbonate acts quickly as an antacid, reacting with hydrochloric acid and releasing carbon dioxide. The gas released ends up stretching the gastric walls, triggering a reflex mechanism that - mediated by the gastrin - increases the release of gastric juices (a bit like the dog biting its tail).

In pharmaceutical preparations with an antacid action, calcium carbonate is sometimes associated with dimethicone, which acts as a carminative reducing the size of the CO ₂ bubbles that form in the stomach, thus attenuating the phenomena of flatulence and belching.

Side effects

Vomiting, nausea, regurgitation, constipation, dry mouth, increased thirst and urination, loss of appetite and metallic aftertaste. When used as an antacid, the combined intake of magnesium hydrate solves the problem of constipation associated with the use of calcium carbonate alone.

In large doses, taken together with large quantities of milk, calcium carbonate becomes responsible for the so-called milk-alkali syndrome, characterized by hypercalcaemia, metabolic alkalosis and hypophosphatemia.

Rarely, ingestion of calcium carbonate can cause allergic reactions, with rapid onset of breathing difficulties, hives, swelling of the face, lips or throat.

Precautions for use

Spontaneous use of any supplement or over-the-counter drug should always obtain the prior medical consent; the use of calcium carbonate, for example, may interfere with other ongoing drug therapies. For this reason, doctor and pharmacist must be informed in advance about any supplement or drug taken at the same time, especially if it is digoxin, antacids, other calcium or vitamin D supplements, or tetracycline antibiotics (tetracycline, demeclocicline, doxycycline, minocycline or oxytetracycline). ). The doctor must also be informed in advance about the possible predisposition to kidney stones and about the presence of gastric, renal or parathyroid diseases.

It is advisable to take calcium carbonate at least a couple of hours away from other drugs, which could diminish their effect.

Do not exceed the recommended intake doses; in case of forgetfulness, take the missed dose as soon as possible, unless it is too close to the next one (never take a double dose to repair the previous forgetfulness).

Intake doses

Recalling the importance of full compliance with medical indications regarding duration, dosages and methods of use, we report the doses normally indicated:

Condition	Calcium carbonate dose **
Osteoporosis	2500 - 7500 mg / day orally, divided into 2-4 daily intakes
Hypocalcemia	900 - 2500 mg / day orally, divided into 2-4 daily intakes; the dose can be adjusted as needed to maintain an optimal level of calcium in the blood.
Dyspepsia	300 - 8000 mg / day orally, divided into 2-4 daily intakes.
Duodenal ulcer *	1250 - 3750 mg / day orally, in 2-4 daily intakes.
Gastric ulcer*	1250 - 3750 mg / day orally, divided into 2-4 daily intakes.
Erosive esophagitis *	1250 - 3750 mg / day orally, divided into 2-4 daily intakes.
Gastroesophageal reflux*	1250 - 3750 mg / day orally, divided into 2-4 daily intakes.

* As mentioned, the biggest limit to the use of calcium carbonate as an antacid, like sodium bicarbonate, is reflex gastric hypersecretion.

** Remember that each gram of calcium carbonate contains 400 mg of elemental calcium. The word "calcium carbonate 2500 mg" is therefore equivalent to "calcium (carbonate) 1000 mg". In the table reference is made to the grams of calcium carbonate (therefore full wording without brackets) and not to those of elementary calcium (wording with the adjective "carbonate" placed in brackets).