Calcium carbonate – Uses and Side effects

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What is calcium carbonate?

Calcium carbonate is an inorganic salt that is insoluble in water. It is primarily used in the treatment of calcium deficiency. It is administered as a calcium supplement, phosphate binder and antacid.

Calcium carbonate appears as a white, odourless powder or as a crystal. Calcium carbonate is available as a tablet, capsule, chewable tablet and liquid that is administered orally.

Chemical structure of calcium carbonate

The chewable calcium carbonate tablet should be chewed thoroughly before swallowing. After taking the oral administration, always drink a full glass of water.

These calcium carbonate supplements effectively treat conditions like hypothyroidism, osteoporosis and rheumatoid arthritis.

How does it work?  

Calcium is naturally found in the human body and stored in the teeth and bones. Besides that, calcium is also present in blood, muscle, extracellular fluid and other body tissues.

Calcium in the blood is 40% bound to albumin and 13% bound to anions, like lactate and phosphate. The rest, 47%, is unbound, free and present as ionised calcium.

The homeostatic control is regulated by the calcium bound in the blood, which plays a vital role in the cellular process.

Calcium carbonate has three pharmacological effects. Calcium carbonate works as an antacid for heartburns, acid reflux, indigestion and stomach upset.

Calcium carbonate neutralises the hydrochloric acid in gastric secretions. When the pH of the stomach increases, it can inhibit the action of the pepsin enzyme.

Calcium carbonate acts as a buffer in the stomach’s acidic environment by neutralising the gastric acid.

Calcium carbonate that enters the stomach dissociates into a carbonate ion (CO32-) and ionised calcium (Ca2+). Carbonate anion will bind to the free protons in the stomach and increases the pH of the stomach by decreasing the concentration of hydrogen ions.

As a result of an increase in the pH of the stomach, bile acids, pepsin and other toxins like Helicobacter pylori activity are inhibited.

Pepsin is an enzyme that degrades tissue protein; bile acids damage the mucosal lining of the stomach and duodenum. It also injures the oesophagus, which is caused by GERD (gastroesophageal reflux disease).

Reports and evidence state that calcium carbonate can heal ulcers due to its acid-neutralising effects. It rebounds the acid by increasing the plasma gastrin levels, and this will increase the prostaglandins. However, there are other alternative mechanisms suggested for ulcer healing.

Calcium carbonate also increases gastrointestinal motility and initiates peristalsis. Peristalsis is the wave-live movement of the muscles that line the gastrointestinal tract.

The chewable calcium carbonate tablets initiate peristalsis in the oesophagus. The partially digested calcium surrounds the oesophagus as free calcium stimulates peristalsis. It promotes the movement of the acid from the oesophagus to the stomach. This will decrease any heartburn symptoms.

Calcium carbonate acts as a phosphate binder and also as a drug chelator in the small intestine. Hyperphosphatemia is high serum phosphate levels. It is a condition that results from increased phosphate intake and decreased phosphate excretion.

Calcium will bind to form an insoluble compound that blocks dietary phosphate or any excess drug absorption. It also helps to excrete the excess calcium. The calcium carbonate used as a calcium supplement acts as a chelating agent in the small intestine to prevent excess absorption and renal calculi formation.

Calcium carbonate also helps to treat negative calcium balance. In such conditions, there will be low serum calcium in the blood. Calcium absorbed in the small intestine actively diffuses with the help of vitamin D, and then the calcium circulates in the blood.

Dosage of calcium carbonate

The dosage of calcium carbonate depends on the person and their health condition. For example, an adult who has the heartburn can take up to 1 gram in a day but should not exceed 7 grams.

Calcium supplements should be in the range of 1–1.2 grams in a day for adults. This can be split and taken orally after meals.

Adults with hyperphosphatemia can take calcium supplements in the range of 1.5–3 grams daily.

If you forget a dosage, you should take the tablet when you remember it. At the same time, do not overdose. If you are near the next dosage, take only the prescribed dosage and remember to dosage regularly without skipping.

Apart from the age and the dosage of calcium carbonate, the absorption can be affected by the pH of the stomach, vitamin D level, oestrogen status and genetic polymorphism. The fractional absorption is highest when taken with the food and when the stomach is acidic.

The factional absorption is as high as 500 mg when consumed with meals. The fractional absorption is also affected by factors like vitamin D levels, absorption factors and body weight.

Absorption of calcium carbonate is affected when a person has achlorhydria or mucosal lining disorder. Achlorhydria is a condition where the stomach does not produce enough hydrochloric acid.

Uses of calcium carbonate  

Calcium is essential for the body. It helps in the formation of healthy bones and teeth. It also helps strengthen your muscles and regulates muscle contraction, heart rhythms and nerve functions.

The other uses of calcium carbonate are briefed below.

Healthy Bones  

 Healthy bones of osteoporosis

Calcium is mainly absorbed through our dietary sources, but as we age, calcium in our bones decreases, and there is low bone density and other bone-related problems.

Calcium is essential for healthy bones, and 99 per cent of it is absorbed and stored by the teeth and bones. The remaining calcium is used by the body to regulate other body functions.

In the human body, the bones get remodelled every day. As a result, calcium movement can be seen in the bones. In young adults and children, the bone is made faster than the breakage. So, there will be an increase in the bone mass. This process will continue till the age of 30.

As we age, new bone formation is delayed, and the old bone breakage will occur at a faster rate. This process is common in post-menopausal women, and if there is less dietary calcium intake, it can lead to osteoporosis.

It is suggested that women should consume more calcium products to avoid any health issues after the age of 30. Dairy products like milk, cheese and yoghurt contain 300 mg of calcium.

Other food sources like leafy vegetables, broccoli, kale and collards contain high calcium levels.


It is a known fact that calcium is required for healthy bones and teeth. Little did we know that calcium is required for healthy muscle?

Calcium plays an essential role in regulating muscle contraction. Your body does not produce calcium, so it is acquired from foods.

Calcium acquired is used in various processes like muscle contraction and blood circulation.

Calcium stored in the sarcoplasmic reticulum regulates skeletal muscle function.

Calcium released binds to the tropomyosin, which allows the interaction of myosin and actin in the sarcomere. This leads to muscle contraction. For healthy muscle contraction, calcium is required.

Nervous systems

The nervous system is the body’s command centre. The primary function of the nervous system is to communicate with the whole body. It sends and receives messages from the brain to other body parts.

Calcium is responsible for initiating a regulatory response when there is tissue injury. Calcium ions will enter the injured cells and activate phospholipases which disrupts the mitochondrial electron transport and releases free radicals.

Neurons contain a large reservoir of substances to bind calcium and also to scavenge free radicals.

Calcium helps to improve blood flow and strengthens the cell structure in the brain. Calcium ions build an ion bridge that gaps between nerve cells, which helps to pass the nerve impulse to specialised cell receptors.

Side Effects of calcium carbonate

Consumption of calcium carbonate can cause certain side effects. However, the side effects vary from person to person.

Little or no urinating

When you are taking calcium tablets and supplements, these are very common. You will experience little or no urination.

Swelling, rapid weight gain

Taking calcium supplements and tablets are compared to placebo, and very few cases reported swelling. However, further research is required to confirm such effects.

High levels of calcium in your blood

When you consume calcium supplements, it can increase the level of calcium in your blood. Overdose of calcium can cause significant health issues. At times, it can be fatal.

The other side effects of calcium carbonate include,  

Precautions before taking this medicine 

Calcium carbonate is administered to people who have low calcium levels. However, patients with certain diseases should be cautious before taking such tablets and supplements.

Kidney disease

Research evidence states that calcium carbonate is effective in people with chronic kidney diseases.

However, there are certain guidelines before taking these supplements. Consult your doctor before taking these supplements; do not take these medications without your doctor’s consent.

Kidney stones

People affected with kidney stones should consider taking such supplements. Without a doctor’s consultation, do not take any supplements.


Calcium consumption can reduce the risk of bone breakage in patients affected with osteoporosis and bone cancer.

According to an article published in NCBI, using calcium supplements has reduced the risk of about 30% of colorectal cancer. This was in accordance with people taking 500 mg per day.

If you are affected by other kinds of cancer, always consult your doctor before taking such supplements.

Parathyroid gland disorder

A parathyroid gland disorder can produce the parathyroid hormone in an abnormal range. It will produce in high quantity or lower quantity.

If the parathyroid hormone is produced in a high quantity, you might have hyperparathyroidism. In such cases, the calcium levels in the blood increase.

So, patients with hyperparathyroidism should consider this before taking such supplements.

High levels of calcium in your blood

Hypercalcemia is a condition where you will have high levels of calcium in the blood. Abnormal calcium levels in the blood can damage and weaken the bones, leading to kidney stones and other complications.

In such cases, you will require diuretics to treat hypercalcemia. It is advised for people affected with hypercalcemia to avoid calcium supplements.

How should I take calcium carbonate?

There are different types of calcium carbonate available. Before taking any supplements, read the instructions given on the label. They would give the dosage and directions to eat.

Calcium carbonate should be taken with the food, whereas calcium citrate can be consumed with or without food.

Calcium carbonate consumed with food helps the stomach acids to absorb the calcium effectively.  

Calcium carbonate is available in various forms like tablets, capsules and liquids. There are chewable tablets available and also capsules that can be swallowed. After consuming these tablets, make sure you drink sufficient water.

When you take calcium carbonate as a liquid, make sure you shake the bottle well before taking it. Also, ask your doctor about the dilutions. The liquid can be a concentrated form and should be diluted with water and then consumed.

Before taking any supplements, always ensure you take the correct dosage. Calcium carbonate should not be taken for more than two weeks unless your doctor prescribes it. Always consult your doctor if you have any side effects.


Calcium carbonate is used when the availability of dietary calcium is low. Calcium is required for various body functions like healthy bones, heart and nervous system.

If you have high calcium or you get enough dietary calcium, you can restrain yourself from taking such supplements. However, before taking any supplements, always consult your doctor. These supplements can be harmful to you and can be fatal.


Is calcium carbonate harmful to your body?

Calcium carbonate is not harmful to your body. It should be taken at the recommended level. A high dosage can kill a person. It can cause other health concerns like abnormal heart rhythms, kidney stones and damage to kidney functions.

Is it ok to take calcium carbonate daily?

The recommended daily intake for adults is 2500 mg per day and for adults above the age of 51 is 2000 mg per day.

Why is calcium carbonate added to formulation?

Calcium carbonate is added to the dietary formulation so that people with low calcium can benefit from these formulations. Some people will not fully absorb calcium due to certain conditions. These formulations can help people with calcium deficiency.
 Calcium carbonate is also used in various formulations like polymer formulations. It acts as a filler and, at the same time, reduces the cost and improves properties.

How does calcium carbonate affect pH?

Calcium carbonate neutralises the hydrochloric acid in gastric secretions. When the pH of the stomach increases, it can inhibit the action of the pepsin enzyme. Calcium carbonate acts as a buffer in the stomach’s acidic environment by neutralising gastric acid.
 Calcium carbonate that enters the stomach dissociates into a carbonate ion (CO32-) and ionised calcium (Ca2+). Carbonate anion will bind to the free protons in the stomach and increases the pH of the stomach by decreasing the concentration of hydrogen ions.


The Information including but not limited to text, graphics, images and other material contained on this blog are intended for education and awareness only. No material on this blog is intended to be a substitute for professional medical help including diagnosis or treatment. It is always advisable to consult medical professional before relying on the content. Neither the Author nor Star Health and Allied Insurance Co. Ltd accepts any responsibility for any potential risk to any visitor/reader.

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