Calcium supplement: Difference between revisions

'''Calcium supplements''' are [[salts]] of [[calcium]] used in a number of conditions. Supplementation is generally only required when there is not enough calcium in the diet. By mouth they are used to treat and prevent [[low blood calcium]], [[osteoporosis]], and [[rickets]].<ref name=AHFS2017/> By [[intravenous|injection into a vein]] they are used for low blood calcium that is resulting in [[muscle spasms]] and for [[high blood potassium]] or [[magnesium toxicity]].

Common side effects include [[constipation]] and nausea. When taken by mouth [[high blood calcium]] is uncommon.<ref name=AHFS2017/> Calcium supplements, unlike calcium from dietary sources, appear to increase the risk of [[kidney stones]]. Adults generally require about a gram of calcium a day. Calcium is particularly [[Calcium in biology|important]] for [[bone]]s, [[muscles]], and [[nerves]].

The medical use of calcium supplements began in the 19th century. It is on the [[WHO Model List of Essential Medicines|World Health Organization's List of Essential Medicines]]. It is available as a [[generic medication]]. In 2020, it was the 204th most commonly prescribed medication in the United States, with more than 2{{nbsp}}million prescriptions. Versions are also sold together with [[vitamin D]]. In 2020, the combination, [[calcium/vitamin D]] was the 215th most commonly prescribed medication in the United States, with more than 2{{nbsp}}million prescriptions.

In healthy people, calcium [[dietary supplement|supplementation]] is not necessary for maintaining [[bone mineral density]], and carries risks that outweigh any benefits. Calcium intake is not significantly associated with hip fracture risk in either men or women. [[United States Preventive Services Task Force|The U.S. Preventive Service Task Force]] recommends against a daily supplement of calcium or vitamin D. Although a slight increase in bone mineral density occurred in healthy children from calcium supplementation, using additional dietary calcium is not justified, according to a 2006 review.

There is good evidence that 1,000&thinsp;mg to 1,500&thinsp;mg of daily calcium supplementation can effect a modest reduction in blood pressure in adults who do not have a blood pressure condition, suggesting that achieving adequate calcium levels may have role in preventing [[high blood pressure]].

The US [[National Cancer Institute]] does not recommend the use of calcium supplements for lowering the risk of cancer. There is weak evidence calcium supplementation might have a preventative effect against developing [[colorectal]] adenomatous [[polyp (medicine)|polyp]]s, but the evidence is not sufficient to recommend such supplementation.

Excessive consumption of calcium carbonate antacids/dietary supplements (such as Tums) over a period of weeks or months can cause [[milk-alkali syndrome]], with symptoms ranging from [[hypercalcemia]] to potentially fatal kidney failure. What constitutes "excessive" consumption is not well known and, it is presumed, varies a great deal from person to person. Persons consuming more than 10&nbsp;grams/day of CaCO₃ (=4 g Ca) are at risk of developing milk-alkali syndrome, but the condition has been reported in at least one person consuming only 2.5&nbsp;grams/day of CaCO₃ (=1 g Ca), an amount usually considered moderate and safe.

A 2023 systematic review found that calcium supplementation is not associated with myocardial infarction, stroke, heart failure admission, and cardiovascular/all-cause mortality.

Calcium supplements may contribute to the development of [[kidney stones]].

Acute calcium poisoning is rare, and difficult to achieve without administering calcium intravenously. For example, the oral [[median lethal dose]] (LD⁵⁰) for rats for [[calcium carbonate]] and [[calcium chloride]] are 6.45 and 1.4&nbsp;g/kg, respectively.

Calcium supplements by mouth diminish the absorption of [[thyroxine]] when taken within four to six hours of each other. Thus, people taking both calcium and thyroxine run the risk of inadequate thyroid hormone replacement and thence [[hypothyroidism]] if they take them simultaneously or near-simultaneously.

The intravenous formulations of calcium include calcium chloride and [[calcium gluconate]].<ref name=AHFS2017/> The forms that are taken by mouth include [[calcium acetate]], calcium carbonate, [[calcium citrate]], calcium gluconate, [[calcium lactate]], and [[calcium phosphate]].

* The absorption of calcium from most food and commonly used dietary supplements is very similar. This is contrary to what many calcium supplement manufacturers claim in their promotional materials.

* [[Calcium carbonate]] is the most common and least expensive calcium supplement. It should be taken with food, and depends on low pH levels (acidic) for proper absorption in the intestine. Some studies suggests that the absorption of calcium from calcium carbonate is similar to the absorption of calcium from milk.

* [[Calcium citrate]] can be taken without food and is the supplement of choice for individuals with achlorhydria or who are taking histamine-2 blockers or proton-pump inhibitors. Calcium citrate is about 21% elemental calcium. One thousand mg will provide 210&nbsp;mg of calcium. It is more expensive than calcium carbonate and more of it must be taken to get the same amount of calcium.

* [[Calcium lactate]] has similar absorption as calcium carbonate, but is more expensive. Calcium lactate and calcium gluconate are less concentrated forms of calcium and are not practical oral supplements.

[[Vitamin D]] is added to some calcium supplements. Proper vitamin D status is important because vitamin D is converted to a hormone in the body, which then induces the synthesis of intestinal proteins responsible for calcium absorption.

For U.S. dietary supplement and food labeling purposes, the amount in a serving is expressed in milligrams and as a percent of Daily Value (%DV). The weight is for the calcium part of the compound – for example, calcium citrate – in the supplement. For calcium labeling purposes 100% of the Daily Value was 1000&nbsp;mg, but in May 2016 it was revised to 1000–1300&nbsp;mg. A table of the pre-change adult Daily Values and references for the revision are provided at [[Reference Daily Intake]]. Food and supplement companies had until July 2018 to comply with the labeling change.