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{{cs1 config|name-list-style=vanc}}
{{expert}}
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 476999632
| Name = Calcium citrate
| ImageFile1 = Calciumcitrat V2.svg
| ImageSize1 = 300px
| ImageCaption1 = 2D structure of calcium citrate
| ImageFile2 = Ca-citrate-tetrahydrate.png
| ImageSize2 = 261
| ImageCaption2 = Calcium citrate tetrahydrate<ref name=str/>
| ImageFile3 = Calcium citrate.jpg
| ImageSize3 = 240
| ImageCaption3 = Calcium citrate tetrahydrate
| IUPACName = 2-hydroxy-1,2,3-propane-tricarboxylic acid calcium salt (2:3)
| OtherNames = E333, tricalcium dicitrate
|Section1={{Chembox Identifiers
| SMILES = [Ca+2].[Ca+2].[Ca+2].O=C([O-])CC(O)(C([O-])=O)CC(=O)[O-].[O-]C(=O)C(O)(CC([O-])=O)CC([O-])=O
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 12584
| ChEBI = 190513
| ChEMBL = 2106123
| EC_number = 212-391-7
| DrugBank = DB11093
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 86117BWO7P
| UNII1_Ref = {{fdacite|correct|FDA}}
| UNII1 = MLM29U2X85
| UNII1_Comment = (tetrahydrate)
| InChI = 1/2C6H8O7.3Ca/c2*7-3(8)1-6(13,5(11)12)2-4(9)10;;;/h2*13H,1-2H2,(H,7,8)(H,9,10)(H,11,12);;;/q;;3*+2/p-6
| InChIKey = FNAQSUUGMSOBHW-CYFPFDDLAZ
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/2C6H8O7.3Ca/c2*7-3(8)1-6(13,5(11)12)2-4(9)10;;;/h2*13H,1-2H2,(H,7,8)(H,9,10)(H,11,12);;;/q;;3*+2/p-6
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = FNAQSUUGMSOBHW-UHFFFAOYSA-H
| CASNo_Ref = {{cascite|correct|PubChem}}
| CASNo = 813-94-5
| CASNo2_Ref = {{cascite|correct|CAS}}
| CASNo2 = 5785-44-4
| CASNo2_Comment = (tetrahydrate)
| PubChem = 13136
}}
|Section2={{Chembox Properties
| Formula = Ca<sub>3</sub>(C<sub>6</sub>H<sub>5</sub>O<sub>7</sub>)<sub>2</sub>
| MolarMass = 498.4334 g/mol (anhydrous) <br> 570.4945 g/mol (tetrahydrate)
| Appearance = White powder
| Odor = odorless
| Density = 1.63 g/cm<sup>3</sup> (anhydrous)<br> 2.00 g/cm<sup>3</sup> (tetrahydrate)<ref name=str/>
| Solubility = 0.85 g/L (18&nbsp;°C) <br> 0.95 g/L (25&nbsp;°C)
| SolubleOther = insoluble in [[ethanol|alcohol]]
| MeltingPt = Decomposes
| BoilingPt = Decomposes
}}
|Section3={{Chembox Structure
| CrystalStruct = Triclinic (tetrahydrate)
| SpaceGroup = P{{overline|1}}, No. 2
| PointGroup =
| LattConst_a = 0.59466(4) nm
| LattConst_b = 1.02247(8) nm
| LattConst_c = 1.66496(13) nm
| LattConst_alpha = 72.213(7)
| LattConst_beta =79.718(7)
| LattConst_gamma =89.791(6)
| LattConst_ref =<ref name=str/>
}}
|Section7={{Chembox Hazards
| MainHazards = Irritant
| NFPA-H = 1
| NFPA-F = 1
| NFPA-R = 0
}}
|Section8={{Chembox Related
| OtherCations = [[Magnesium citrate]]<br />[[Strontium citrate]]
| OtherCompounds =
}}
}}


'''Calcium citrate''' is the [[calcium salt]] of [[citric acid]]. It is commonly used as a [[food additive]] ([[E number|E333]]), usually as a [[preservative]], but sometimes for [[Flavoring|flavor]]. In this sense, it is similar to [[Trisodium citrate|sodium citrate]]. Calcium citrate is also found in some dietary calcium supplements (e.g. [[Citracal]] or [[Caltrate]]). Calcium makes up 24.1% of calcium citrate (anhydrous) and 21.1% of calcium citrate (tetrahydrate) by mass. The tetrahydrate occurs in nature as the mineral [[Earlandite]].
{| class="toccolours" border="1" style="float: right; clear: right; margin: 0 0 1em 1em; border-collapse: collapse;"
! {{chembox header}}| '''{{PAGENAME}}''' <!-- replace if not identical with the article name -->
|-
| align="center" colspan="2" bgcolor="#ffffff" | [[Image:Calcium_citrate.PNG|242px|{{PAGENAME}}]] <!-- replace if not identical with the pagename -->
|-
| [[IUPAC nomenclature|Chemical name]]
| Tricalcium citrate
|-
| [[Chemical formula]]
| Ca<sub>3</sub>(C<sub>6</sub>H<sub>5</sub>O<sub>7</sub>)<sub>2</sub>
|-
| [[Molecular mass]]
| 498.46 g/mol
|-
| [[CAS registry number|CAS number]]
| [5785-44-4]
|-
| [[Density]]
| 1.63 g/cm<sup>3</sup>
|-
| [[Melting point]]
| unknown °C
|-
| [[Boiling point]]
| unknown °C
|-
| [[Simplified molecular input line entry specification|SMILES]]
|
C(C(=O)[O-])C(CC(=O)[O-])(C(=O)[O-])O.<br>C(C(=O)[O-])C(CC(=O)[O-])(C(=O)[O-])O.<br>[Ca+2].[Ca+2].[Ca+2]
|-
| {{chembox header}} | <small>[[wikipedia:Chemical infobox|Disclaimer and references]]</small>
|-
|}


==Chemical properties==
'''Calcium citrate''' is the [[calcium]] [[salt]] of [[citric acid]]. Calcium citrate is a form of elemental calcium found in calcium supplements, like [http://www.citracal.com/ Citracal®], the leading calcium citrate brand in the United States. Calcium citrate can be taken at any time of day or night. Stomach acid does not affect the rate of absorbtion and consequently citrate supplements need not be taken with food. Additionally, calcium citrate supplements, like Citracal®, do not increase the risk of kidney stones.
Calcium citrate is sparingly soluble in water. Needle-shaped crystals of tricalcium dicitrate tetrahydrate [Ca<sub>3</sub>(C<sub>6</sub>H<sub>5</sub>O<sub>7</sub>)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>]·2H<sub>2</sub>O were obtained by hydrothermal synthesis. The crystal structure comprises a three-dimensional network in which eightfold coordinated Ca<sup>2+</sup> cations are linked by citrate anions and hydrogen bonds between two non-coordinating crystal water molecules and two coordinating water molecules.<ref name=str>
{{cite journal
| first1= Eberhardt | last1= Herdtweck
| first2= Tobias | last2= Kornprobst
| first3 =Roland | last3=Sieber
| first4 = Leo | last4= Straver
| first5 = Johann | last5= Plank
| title= Crystal Structure, Synthesis, and Properties of tri-Calcium di-Citrate tetra-Hydrate [Ca<sub>3</sub>(C<sub>6</sub>H<sub>5</sub>O<sub>7</sub>)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>]·2H<sub>2</sub>O
| journal= Zeitschrift für anorganische und allgemeine Chemie| year = 2011| volume= 637| issue= 6| pages= 655–659| doi= 10.1002/zaac.201100088
}}</ref>


==Production==
Calcium citrate supplements come in a variety of forms, including [http://www.citracal.com/ Citracal®], Creamy Bites-a dietary supplement of calcium citrate and vitamin D3 in easy-to-eat bite-sized nutritional treats. Citracal® Creamy Bites come in three flavors: Chocolate Fudge, Caramel, and Lemon Cream. Each piece provides 500 mg calcium, in the form of calcium citrate, and 200 IU of vitamin D3.
Calcium citrate is an intermediate in the isolation of [[citric acid]] from the fungal [[fermentation]] process by which citric acid is produced industrially.<ref>{{cite web|url=http://www.lime.org/ENV02/Other802.htm|title=Use of Lime in the Chemical Industry|access-date=2006-11-25|publisher=National Lime Association |archive-url = https://web.archive.org/web/20060929115254/http://www.lime.org/ENV02/Other802.htm |archive-date = 2006-09-29}}</ref> The citric acid in the broth solution is neutralized by [[limewater]], precipitating insoluble calcium citrate. This is then filtered off from the rest of the broth and washed to give clean calcium citrate.
: 3 Ca(OH)<sub>2(s)</sub> + 2 C<sub>6</sub>H<sub>8</sub>O<sub>7(l)</sub> → Ca<sub>3</sub>(C<sub>6</sub>H<sub>5</sub>O<sub>7</sub>)<sub>2(s)</sub> + 6 H<sub>2</sub>O<sub>(l)</sub>


The calcium citrate thus produced may be sold as-is, or it may be converted to citric acid using dilute sulfuric acid.


== Medical uses ==
It's primarily sold as a [[food supplement]] of calcium.


=== Bioavailability ===
It is commonly used as a [[food additive]] (E333), usually as a [[preservative]], but sometimes for [[flavor]]. In this sense, it is similar to [[sodium citrate]]. Calcium citrate is also used as a [[water softener]].
In many individuals, [[bioavailability]] of calcium citrate is found to be equal to that of the cheaper [[calcium carbonate]] (CaCO<sub>3</sub>).<ref>
{{cite journal
|vauthors=Heaney RP, Dowell MS, Bierman J, Hale CA, Bendich A | title = Absorbability and cost-effectiveness in calcium supplementation
| journal = [[Journal of the American College of Nutrition]]
| volume = 20
| issue = 3
| pages = 239–46
| date =2001
| doi =10.1080/07315724.2001.10719038
| pmid =11444420
| s2cid = 206488
}}</ref> However, alterations to the digestive tract may change how calcium is digested and absorbed. Unlike calcium carbonate, which is basic and neutralizes [[Gastric acid|stomach acid]], calcium citrate has no effect on stomach acid.<ref name="hhp">{{cite web|title=What you need to know about calcium|date=9 June 2009|url=http://www.health.harvard.edu/newsweek/What_you_need_to_know_about_calcium.htm|publisher=Harvard Health Publications|access-date=4 August 2014}}</ref>{{Better source needed|reason=The current source is insufficiently reliable ([[WP:NOTRS]]).|date=May 2023}} Calcium carbonate is harder to digest than calcium citrate,{{r|hhp}} and calcium carbonate carries a risk of "acid rebound" (the stomach overcompensates by producing more acid),{{r|hhp}} so individuals who are sensitive to antacids or who have difficulty producing adequate stomach acid may choose calcium citrate over calcium carbonate for supplementation.


According to a 2009 research into calcium absorption after gastric bypass surgery,<ref>
==Chemical properties==
{{cite journal
Like citric acid, calcium citrate has a [[sour]] taste. Like other salts, however, it also has a [[salty]] taste. For this reason, citrates such as sodium and calcium citrate are commonly known as ''sour salt''.
| vauthors=Tondapu P, Provost D, Adams-Huet B, Sims T, Chang C, Sakhaee K
| title = Comparison of the Absorption of Calcium Carbonate and Calcium Citrate after Roux-en-Y Gastric Bypass
| journal = Obesity Surgery
| volume = 19
| issue = 9
| pages = 1256–1261
| date =June 2009
| doi = 10.1007/s11695-009-9850-6
| pmid =19437082
| pmc =4469176
}}</ref> calcium citrate may have improved bioavailability over calcium carbonate in Roux-en-Y gastric bypass patients who are taking calcium citrate as a [[dietary supplement]] after surgery. This is mainly due to the changes related to where calcium absorption occurs in the digestive tract of these individuals.


== See also ==


* [[Calcium gluconate]]
Solubility in water 25C is 0.095 g/100 ml
* [[Glucono delta-lactone]]


==References==
Melt Point:120C (loses water)
{{Reflist|2}}


==External links==
Boiling Point: Decomposes
*[http://www.cancer.gov/drugdictionary/?CdrID=41817 National Cancer Institute]


{{Calcium compounds}}
==Biological role==
{{citrus}}
Calcium citrate supplements may increase aluminium toxicity. Patients with renal disease are at an increased risk of toxicity.

[[Bioavailability]] is 2.5 times higher than [[calcium carbonate]]. For this reason, patients who have undergone the [[Roux-en-Y]] variety of weight-loss surgery (also known as [[gastric bypass]]) are usually instructed to take calcium citrate as a dietary supplement.

==[[Organometallic]] importance==
Calcium citrate is used as a water softener because the citrate [[chelate]]s unwanted metal ions.


{{DEFAULTSORT:Calcium Citrate}}
[[Category:Citrates]]
[[Category:Citrates]]
[[Category:Calcium compounds]]
[[Category:Calcium compounds]]
[[Category:E-number additives]]

[[es:Citrato de calcio]]

Latest revision as of 13:08, 24 January 2024

Calcium citrate

2D structure of calcium citrate

Calcium citrate tetrahydrate[1]

Calcium citrate tetrahydrate
Names
IUPAC name
2-hydroxy-1,2,3-propane-tricarboxylic acid calcium salt (2:3)
Other names
E333, tricalcium dicitrate
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.011.265 Edit this at Wikidata
EC Number
  • 212-391-7
E number E333 (antioxidants, ...)
UNII
  • InChI=1S/2C6H8O7.3Ca/c2*7-3(8)1-6(13,5(11)12)2-4(9)10;;;/h2*13H,1-2H2,(H,7,8)(H,9,10)(H,11,12);;;/q;;3*+2/p-6 checkY
    Key: FNAQSUUGMSOBHW-UHFFFAOYSA-H checkY
  • InChI=1/2C6H8O7.3Ca/c2*7-3(8)1-6(13,5(11)12)2-4(9)10;;;/h2*13H,1-2H2,(H,7,8)(H,9,10)(H,11,12);;;/q;;3*+2/p-6
    Key: FNAQSUUGMSOBHW-CYFPFDDLAZ
  • [Ca+2].[Ca+2].[Ca+2].O=C([O-])CC(O)(C([O-])=O)CC(=O)[O-].[O-]C(=O)C(O)(CC([O-])=O)CC([O-])=O
Properties
Ca3(C6H5O7)2
Molar mass 498.4334 g/mol (anhydrous)
570.4945 g/mol (tetrahydrate)
Appearance White powder
Odor odorless
Density 1.63 g/cm3 (anhydrous)
2.00 g/cm3 (tetrahydrate)[1]
Melting point Decomposes
Boiling point Decomposes
0.85 g/L (18 °C)
0.95 g/L (25 °C)
Solubility insoluble in alcohol
Structure
Triclinic (tetrahydrate)
P1, No. 2
a = 0.59466(4) nm, b = 1.02247(8) nm, c = 1.66496(13) nm
α = 72.213(7)°, β = 79.718(7)°, γ = 89.791(6)°[1]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Irritant
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
1
0
Related compounds
Other cations
 Magnesium citrate
Strontium citrate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Calcium citrate is the calcium salt of citric acid. It is commonly used as a food additive (E333), usually as a preservative, but sometimes for flavor. In this sense, it is similar to sodium citrate. Calcium citrate is also found in some dietary calcium supplements (e.g. Citracal or Caltrate). Calcium makes up 24.1% of calcium citrate (anhydrous) and 21.1% of calcium citrate (tetrahydrate) by mass. The tetrahydrate occurs in nature as the mineral Earlandite.

Chemical properties

[edit]

Calcium citrate is sparingly soluble in water. Needle-shaped crystals of tricalcium dicitrate tetrahydrate [Ca3(C6H5O7)2(H2O)2]·2H2O were obtained by hydrothermal synthesis. The crystal structure comprises a three-dimensional network in which eightfold coordinated Ca2+ cations are linked by citrate anions and hydrogen bonds between two non-coordinating crystal water molecules and two coordinating water molecules.[1]

Production

[edit]

Calcium citrate is an intermediate in the isolation of citric acid from the fungal fermentation process by which citric acid is produced industrially.[2] The citric acid in the broth solution is neutralized by limewater, precipitating insoluble calcium citrate. This is then filtered off from the rest of the broth and washed to give clean calcium citrate.

3 Ca(OH)2(s) + 2 C6H8O7(l) → Ca3(C6H5O7)2(s) + 6 H2O(l)

The calcium citrate thus produced may be sold as-is, or it may be converted to citric acid using dilute sulfuric acid.

Medical uses

[edit]

It's primarily sold as a food supplement of calcium.

Bioavailability

[edit]

In many individuals, bioavailability of calcium citrate is found to be equal to that of the cheaper calcium carbonate (CaCO3).[3] However, alterations to the digestive tract may change how calcium is digested and absorbed. Unlike calcium carbonate, which is basic and neutralizes stomach acid, calcium citrate has no effect on stomach acid.[4][better source needed] Calcium carbonate is harder to digest than calcium citrate,[4] and calcium carbonate carries a risk of "acid rebound" (the stomach overcompensates by producing more acid),[4] so individuals who are sensitive to antacids or who have difficulty producing adequate stomach acid may choose calcium citrate over calcium carbonate for supplementation.

According to a 2009 research into calcium absorption after gastric bypass surgery,[5] calcium citrate may have improved bioavailability over calcium carbonate in Roux-en-Y gastric bypass patients who are taking calcium citrate as a dietary supplement after surgery. This is mainly due to the changes related to where calcium absorption occurs in the digestive tract of these individuals.

See also

[edit]

References

[edit]
  1. ^ a b c d Herdtweck E, Kornprobst T, Sieber R, Straver L, Plank J (2011). "Crystal Structure, Synthesis, and Properties of tri-Calcium di-Citrate tetra-Hydrate [Ca3(C6H5O7)2(H2O)2]·2H2O". Zeitschrift für anorganische und allgemeine Chemie. 637 (6): 655–659. doi:10.1002/zaac.201100088.
  2. ^ "Use of Lime in the Chemical Industry". National Lime Association. Archived from the original on 2006-09-29. Retrieved 2006-11-25.
  3. ^ Heaney RP, Dowell MS, Bierman J, Hale CA, Bendich A (2001). "Absorbability and cost-effectiveness in calcium supplementation". Journal of the American College of Nutrition. 20 (3): 239–46. doi:10.1080/07315724.2001.10719038. PMID 11444420. S2CID 206488.
  4. ^ a b c "What you need to know about calcium". Harvard Health Publications. 9 June 2009. Retrieved 4 August 2014.
  5. ^ Tondapu P, Provost D, Adams-Huet B, Sims T, Chang C, Sakhaee K (June 2009). "Comparison of the Absorption of Calcium Carbonate and Calcium Citrate after Roux-en-Y Gastric Bypass". Obesity Surgery. 19 (9): 1256–1261. doi:10.1007/s11695-009-9850-6. PMC 4469176. PMID 19437082.
[edit]
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