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Calcium Carbonate Vs. Calcium Citrate

Calcium Carbonate Vs. Calcium Citrate

When it comes to calcium supplements, calcium citrate and calcium carbonate are the two popular types. This article provides a brief overview about the differences between them.
Sonia Nair
Last Updated: Jun 3, 2018
The performance of a calcium supplement can be assessed with a simple home test for measuring the level of disintegration. A good quality tablet will disintegrate within 30 minutes, if placed in room-temperature white vinegar.
Calcium is a mineral that is essential for the proper functioning of the human body. It is necessary for the healthy growth of bones and teeth in kids; and for maintaining bone health in adults. Calcium is required for expansion and contraction of blood vessels and muscles, secretion of hormones and enzymes, and transmission of impulses through the nerves. Almost 99% of the calcium absorbed in the body is stored in bones and teeth, and less than 1% is used for other functions. The body maintains the level of calcium in the blood, muscles, and intercellular fluids; in order to carry out these functions.
Calcium absorption in the body is subject to various factors. The amount of calcium absorbed may vary with the type of calcium supplement, acidic conditions of the digestive tract, levels of vitamin D and estrogen, etc. If the food you consume is deficient in calcium, or if your body does not absorb the mineral properly; you may be advised to start supplements. Such supplements are available in different types - calcium carbonate, calcium citrate, calcium phosphate, calcium gluconate, calcium lactate, etc. The main types are calcium carbonate and calcium citrate. Which one is better? Let us find out.
Differences Between Calcium Carbonate and Calcium Citrate
Elemental Calcium Content
Concentration of elemental calcium (per pill) is high in calcium carbonate. So less number of pills are required to meet the daily requirement. When compared to calcium carbonate, calcium citrate contains less elemental calcium. In that case, you need to take more pills to meet the daily requirement. While calcium carbonate has 40% elemental calcium by weight, calcium citrate has 21% only. Usually, the number in the name of the supplement indicates the amount of elemental calcium in each pill, but go through the label to confirm the same.

Level of Absorption
When it comes to absorbability, calcium citrate is said to be better, as it disintegrates and dissolves easily. Calcium carbonate needs more stomach acid for absorption, and this supplement is taken after meals. So it is not recommended for those who take acid suppressing medication. The same applies to those who produce less stomach acids. According to recent studies, no significant difference was seen in the level of absorption of both these supplements.

Side Effects
Calcium supplements are not known to cause grave side effects, but some users may experience bloating and constipation. Mostly, calcium carbonate is associated with such side effects, which can be avoided to some extent by taking the supplement along with meals. This supplement may also cause dry mouth, loss of appetite, increased urination, etc. Even those who use calcium citrate may experience such side effects. Though uncommon, allergic reactions may also develop in some users. Excessive intake of calcium supplements may lead to hypercalcemia.

Drug Interactions
Both calcium carbonate and calcium citrate may interact with drugs, like phosphate binders, diuretics, thiazides, etc. They may affect absorption of fluoroquinolones, levothyroxine, and tetracycline antibiotics. Intravenous administration of ceftriaxone and calcium-containing products is said to be harmful for the body. So it advisable to consult your physician regarding use of other medicines, along with calcium supplements.

In short, both these supplements are almost similar in all aspects, except the price. Calcium carbonate is more cost-effective than calcium citrate. Calcium carbonate has more elemental calcium, but calcium citrate is said to be easily absorbable. Usually, health experts recommend calcium carbonate that is less expensive, effective, and well tolerated. However, calcium citrate is ideal for those who are using acid suppressing medication. It is always better to use the supplement that is prescribed by your health care provider. Stick to the recommended daily dosage. The human body cannot absorb more than 500 milligrams of calcium at a time. So there is no point in taking a single, high dose. Ensure that you buy good quality supplements from reputed manufacturers. As they come under the category of nutritional supplements, these products are not well regulated. Try to get calcium supplements with the 'USP' (United States Pharmacopeia) symbol. Otherwise, get products certified by Consumer Labs International, Natural Products Association, or NSF.
While in most cases, a proper diet can satisfy the calcium requirement of a normal human being, some people may experience deficiency of this mineral, either because of insufficient intake through foods, or due to some medical conditions that inhibit calcium absorption in the body. Those who come under the latter category must treat the underlying condition. Others must either increase intake of calcium-rich foods or take calcium supplements. A normal healthy adult must have around 1000 to 1200 milligrams of calcium per day.
Disclaimer: This article is for informational purposes only and should not be used as a replacement for expert medical advice.