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Calcium Carbonate vs Calcium Citrate - What is the difference?

Calcium Carbonate vs Calcium Citrate - What is the difference?

Table of Contents

  1. Introduction
  2. What is Calcium Carbonate?
  3. What is Calcium Citrate?
  4. Calcium Carbonate vs Calcium Citrate
  5. How much Calcium Carbonate or Calcium Citrate should I take?
  6. What Helps Calcium Absorption?
  7. What are the Side Effects of Calcium Supplements?
  8. Who should take Calcium Supplements?
  9. Types of calcium carbonate and calcium citrate on the market
  10. Conclusion


    Our body needs calcium in order to build and maintain strong bones. Calcium also helps in other body functions such as blood clotting and contracting muscles. Lack of calcium may result in weakened bones and osteoporosis in older women. 

    While this major mineral should be obtained from our diets, many of us are not getting the amount of calcium that we need. This is where calcium supplements can help. 

    What is calcium carbonate?

    Calcium carbonate, or CaCO3 is a mineral that is widely available throughout the world. Common forms of calcium carbonate include chalk, limestone and marble. The sedimentation of shells, shellfish, snails, and corals over millions of years produces calcium carbonate. Calcium carbonate is one of the most versatile materials and its wide availability makes it an inexpensive mineral.  

    In industrial applications, it is a mineral that is used as a filler, as well as a coating pigment in the paper, plastic, paint and coating industries. In construction, calcium carbonate is an ingredient in the making of cement, and mortar for building bricks and concrete blocks.

    The food industry also uses calcium carbonate. It can be found in dry mix dessert mixes, dough, baking powder and even plays a role in wine production. Calcium carbonate is also used as a food preservative as well as a color retainer. Besides this, it is sometimes added to calcium fortified soy milk and almond milk products.

    In the health industry, calcium carbonate is used extensively for calcium supplements, antacids and also as a base material for medicine tablets. It is also used as a phosphate binder for patients suffering from hyperphosphatemia, which is an electrolyte disorder.

    What is calcium citrate?

    Calcium citrate is the calcium salt of citric acid. Its tetrahydrate occurs in nature as Earlandite. It is produced industrially during the production of citric acid.

    It is used in the food industry as a food preservative and also for flavoring. Other than the food industry, calcium citrate is commonly used in calcium supplements.

    Calcium Carbonate vs Calcium Citrate 

    Calcium supplements come in two forms – Calcium Carbonate and Calcium Citrate. The difference between calcium carbonate and calcium citrate is the amount of elemental calcium in it. Elemental calcium refers to the amount of actual calcium in the calcium pill. 

    Calcium carbonate contains 40% elemental calcium while calcium citrate contains 20% elemental calcium.

    Calcium citrate usually works as well as calcium carbonate. One of the main differences between calcium carbonate and calcium citrate is that calcium citrate does not have any effect on stomach acid. It is easier to digest and does not encourage acid rebound. Thus, calcium citrate is a better choice for those who have sensitive stomachs, or have problems producing stomach acids.

    How much calcium carbonate or calcium citrate should I take? 

    This is where the elemental calcium comes into consideration. 

    For example, 600mg of calcium carbonate would contain 240mg of elemental calcium while 600mg of calcium citrate would contain 120mg of elemental calcium.

    The amount of calcium carbonate or calcium citrate that you should take boils down to gender and age as recommended daily intake. The recommended daily intake for calcium is as follows:

    -       Women below 50: : 1,000 mg per day

    -       Women over 50: 1,200 mg per day

    -       Men below 70: 1,000 mg per day

    -       Men 70 and over: 1,200 mg per day.

    You should also make sure not to go over the recommended upper limits of calcium intake, which is 2,500mg for adults below 50 and 2,000mg for adults over 50.

    It is also important to remember to add in the amount of calcium that you get from both your diet and your supplements when calculating your daily calcium intake.  

    What helps calcium absorption? 

    There are several factors that affect calcium absorption. Having a healthy diet that has sufficient Vitamin D and Magnesium will help keep calcium deficiency at bay. Vitamin D and Magnesium will help your body absorb the calcium that you consume.

    Vitamin D

    On the other hand, Vitamin D is a nutrient that is very much needed as it will help your body to effectively absorb calcium. Good sources of Vitamin D include Vitamin D fortified milk, egg yolks, and fatty fish. Your skin will also produce Vitamin D in reaction to sunlight.

    Adults under the age of 50 need 400 to 800 international units (IU) of Vitamin D daily. Those who are above 50 need 800 to 1,000 IU of Vitamin D daily. As Vitamin D is vital for calcium absorption, the problem might not be a lack of calcium in your diet, but the lack of Vitamin D.


    Another nutrient that plays an important role in calcium absorption is magnesium. Magnesium suppresses the secretion of the parathyroid hormone (PTH). This is noteworthy as increased levels of PTH will cause calcium to be drawn out of bones.

    Therefore, one of the consequences of a magnesium deficiency is a decrease in calcium absorption. To overcome vitamin D deficiency and magnesium deficiency, you can consider taking a calcium supplement that contains Vitamin D and magnesium.

    What interferes with the absorption of calcium?

    A diet that contains high levels of salt, or sodium, will affect calcium absorption as salt breaks up calcium. A diet that is high in phytic acid will also interfere with calcium absorption. Phytic acid causes calcium to bind with other minerals. When this happens, these minerals become insoluble and will pass through your body without being absorbed.

    What are the side effects of calcium supplements? 

    Calcium supplements are safe when taken in the recommended amounts. Side effects are usually minor, such as gas and belching. 

    However, calcium can be unsafe if it is taken in high doses. Taking more than is needed can cause milk-alkali syndrome, which may result in renal stones, kidney failure and even death. 

    Some studies have also linked taking calcium that is over the recommended daily intake to increased risk of heart attack. This seems to be more prevalent in older people. However, other studies demonstrate that there is no link between calcium and heart attack.

    How to avoid these side effects? 

    In order to avoid these side effects, be sure not to exceed the recommended daily intake of calcium, which is 1,000 to 1,2000mg per day. You will need to consider calcium from your daily diet and calcium from your supplement when calculating your total daily intake. Consume adequate, and not excessive amounts of calcium. 

    Who should take calcium supplements? 

    Calcium supplements are usually taken by those who are unable to get the recommended amount of daily calcium in their diets. As older women are at a higher risk of osteoporosis, doctors will usually recommend that older women take calcium supplements.

    You should also consider taking calcium supplements if you are on a vegan diet, or have a diet that is high in protein or sodium. Calcium supplements are also recommended for those who have health conditions such as Crohn’s disease or inflammatory bowel disease as these conditions reduce your body’s calcium absorption capability. Those who have been treated with corticosteroids for a long period of time should also consider calcium supplements.

    It is also vital that women who are pregnant have sufficient calcium. This is because a woman’s body will ensure that the growing baby receives enough calcium as they develop, even if it means taking calcium from the mother’s bones or teeth.

    Types of calcium carbonate and calcium citrate on the market

    Calcium supplements are widely available on the market. There are supplements that contain just calcium carbonate or calcium citrate. 

    Some supplements also combine Vitamin D and Magnesium in their formulas to promote better calcium absorption. Holistic Way High Strength Calcium Magnesium Zinc is one of the best calcium supplements that contains both vitamin D and magnesium.


    Calcium is a much needed mineral in our bodies. The lack of it will bring about many health issues such as osteoporosis. Two main types of calcium supplements are calcium carbonate and calcium citrate. They differ from each other in terms of elemental calcium that they contain. Besides taking calcium supplements, it is also important to make sure that our bodies have sufficient Vitamin D and Magnesium as these nutrients play a big role in our bodies ability to absorb calcium. When choosing which calcium pill to take, do consider how much calcium from supplements that you need. It is always wise to check with your doctor before starting on any supplements. 


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