Calcium Citrate, Calcium Carbonate and Calcium Phosphate

Calcium carbonate, Calcium citrate, and Calcium phosphate are three different types of calcium supplements that vary in their amount of elemental calcium, absorption, cost, and side effects. Algae Calcium is also known as a natural calcium source. All these are explained below for your clear understanding.

Types of calcium and its supplements
Types of calcium and its supplements

Calcium carbonate contains 40% elemental calcium, which means that 500 mg of calcium carbonate provides 200 mg of elemental calcium. It is cheaper and more widely available than other forms, but it requires stomach acid for optimal absorption. Therefore, it is best taken with food or a source of acid, such as vitamin C. However, calcium carbonate may cause gas, bloating, or constipation in some people.

This is also for your information; the calcium carbonate isn’t directly absorbed until gastric acid reacts with it to form a soluble form like calcium hydroxide (less absorbed form). If calcium carbonate isn’t reacted with gastric acid or acidic juices, then this will cause bloating in your abdomen which is a known common side effect of this form mentioned in side effects also.

Some good sources of calcium include:

    • Yogurt: You can take Dairy foods e.g. yogurt, yogurt is a source of calcium  (in the morning to boost your prebiotics also), 
    • Milk & Cheese: Warm Milk  (best to take at evening) cheese (in the morning for best energy source for whole day activity).
    • Egg: You must add eggs in you daily diet plan for calcium as well as albumin(carrier protein) source. 
    • Calcium fortified foods: You may add Calcium-fortified foods like soy products, cereals, and juices in your daily meal.
    • Leafy Green vegetables: By adding the Leafy green vegetables like kale, spinach, and bok choy in weekly food planner.
    • Nuts and seeds: Nuts and Seeds like almonds, sesame seeds, and chia seeds may boost you calcium.
    • Fish:  Fish with edible bones like sardines and canned salmon.

Therapeutic uses of Calcium Carbonate:

Types of calcium and its supplements
Types of calcium and its supplements

Calcium carbonate has several therapeutic uses, such as:

    • Calcium supplement along with vitamin D in case of rickets (bones softening, deformities)

    • Calcium deficiency in pregnant women due to increased body demand.

    • Peptic ulcer neutralizes acid in the stomach.

    • Adjunctive drug of choice for hyperphosphatemia in renal cases.

    • A dietary supplement to prevent or treat calcium deficiency and support bone health.

    • An antacid to relieve heartburn (along with sucralfate and menthol), acid indigestion, and upset stomach.

    • A phosphate binder to lower high phosphate levels in people with kidney disease.

Daily dose of calcium

Before recommending the dose, always keep in mind the patient’s age and body weight for dose calculation. The dosage of calcium carbonate depends on the purpose and the product you are using. Generally, the following guidelines apply:

    • For calcium supplementation, the recommended dose is 500 mg to 4,000 mg of calcium carbonate (200 mg to 1,600 mg of elemental calcium) per day, divided into smaller doses and taken with meals1

    • For antacid use, the recommended dose is 1,000 mg to 3,531 mg of calcium carbonate (400 mg to 1,417 mg of elemental calcium) per day, as needed for symptoms. The maximum dose is 6,750 mg to 7,500 mg of calcium carbonate (2,700 mg to 3,000 mg of elemental calcium) per day. Do not use for more than 2 weeks unless advised by a doctor.

Side effects due to high intake of calcium are as follows.

    • Hypercalcemia

    • Hypercalciuria

    • Renal failure

    • Abdominal Gas,

    • Bloating

    • Constipation.

    • Reduced absorption of other medications or nutrients, such as tetracycline, iron, or zinc.

    • High levels of calcium in the blood, which can cause nausea, vomiting, confusion, or muscle weakness.


It is important to take calcium carbonate as directed by your doctor or pharmacist and to inform them of any other medications or supplements you are taking. You should also avoid taking too much calcium carbonate or using it for longer than 2 weeks without medical advice

Calcium phosphate

Calcium phosphate contains 38% elemental calcium, which means that 500 mg of calcium phosphate provides 190 mg of elemental calcium depending upon the type of calcium citrate type (Calcium mono phosphate, Calcium di-phosphate, or Calcium triphosphate). It is similar to calcium carbonate in terms of cost and availability, but it has a lower risk of gastrointestinal side effects. However, calcium phosphate may increase the risk of kidney stones in some people and may interfere with the absorption of iron and zinc.

Therapeutic uses of Calcium Phosphate

Calcium phosphate is a mineral that contains both calcium and phosphorus, two elements that are essential for many functions in the body. Calcium phosphate is found naturally in bones and teeth, where it forms a large part of their structure and strength. Calcium phosphate also has other roles in the body, such as:

  • Helping blood clotting and muscle contraction.
  • Supporting nerve function and hormone secretion.
  • Regulating acid-base balance and enzyme activity.
  • Participating in DNA and protein synthesis.

Calcium phosphate can also be taken as a supplement to increase the intake of calcium and phosphorus, especially for people who have low levels of these minerals or who have certain conditions that affect their absorption or metabolism. Some examples of such conditions are:

  • Hypocalcemia, which is low calcium in the blood.
  • Osteoporosis, which is a loss of bone density and mass.
  • Hypoparathyroidism, which is a disorder of the parathyroid glands that produce a hormone that regulates calcium and phosphorus levels.
  • Vitamin D deficiency, which impairs the absorption of calcium from food.

Calcium phosphate supplements are available in different forms, such as tablets, powders, or gummies.

How can I prevent kidney stones from calcium supplements?

Kidney stones are hard deposits of minerals and salts that form in the urinary tract. Calcium supplements can increase the risk of kidney stones, especially if taken in high doses or without food. However, there are some ways to prevent kidney stones from calcium supplements, such as:

  • Drink plenty of water. Drinking at least 2 liters of water per day can help dilute the urine and flush out any excess calcium or other substances that can form stones.
  • Take calcium supplements with meals. Taking calcium supplements with food can help reduce the amount of calcium that is absorbed into the bloodstream and excreted into the urine. This can lower the risk of calcium oxalate stones, the most common type of kidney stones.
  • Avoid taking too much calcium. The recommended daily intake of calcium for adults is 1,000
  • Use a more soluble form of calcium like calcium citrate, or take vitamin C to solubilize the calcium stones.

Note: The best type of calcium supplement for you depends on your individual needs, preferences, budget, and medical conditions. You should consult your doctor or dietitian before taking any calcium supplement to determine the appropriate type and dose for you.

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