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Calcium phosphate (mineral salt, E341)

Calcium phosphate

Calcium phosphate is a calcium supplement and the food additive E341, and it does raise calcium intake, but we found no good trial showing it works better than calcium carbonate or citrate, and the bone-protection evidence for calcium supplements in general is weak (see calcium carbonate). It also delivers phosphate, which matters for people with kidney disease and for heavy eaters of processed food, because EFSA found phosphate exposure from the diet and from supplements can exceed its acceptable daily intake. A separate casein-based form of amorphous calcium phosphate (CPP-ACP) used in tooth mousse has limited, mixed evidence for remineralising early enamel lesions.

Updated
30 September 2026
White calcium tablets beside a glass of milk
At a glance
Last reviewed 30 September 2026
Evidence
Limited
Best for
Calcium supplement form
Typical form & use
Tablet; label gives elemental calcium
Onset
4+ weeks
Safety
Adds phosphate, so ask first with kidney disease. No interactions in our data.
Check with your medications →

What it's used for

Evidence is rated per use. The same ingredient can be strong for one thing and traditional for another.

UseEvidenceWhat the research shows
Calcium supplement (bone health)LimitedA 2007 review of supplement forms says calcium carbonate and citrate are the common, best-studied forms, and that research on hydroxyapatite (another calcium phosphate) as a calcium source is limited, so it does not recommend it. It gives 500 mg of elemental calcium as the most to take at one time. We found no human trial of calcium phosphate on fractures, so the bone-health rating rests on calcium supplements in general, which we rate 2 on the calcium carbonate page (fracture reduction little or none in the largest meta-analysis).2
How well the calcium is absorbed compared with carbonateTraditionalThe only head-to-head figures we opened are from a laboratory digestion model, not people: tri-calcium phosphate had lower bioaccessibility (46% against 74% for carbonate) and lower modelled bioavailability (1.85% against 3.93%). In 27 fasted women, 800 mg of calcium as phosphate was not reported to change iron absorption compared with calcium chloride, whereas calcium citrate lowered it, so the salt matters for that interaction. We cannot say from these sources how the two salts compare for absorption in people.3,4
Tooth remineralisation (CPP-ACP and other calcium phosphate pastes)LimitedCPP-ACP is casein phosphopeptide bound to amorphous calcium phosphate, sold as tooth mousse and in some toothpastes and gums. A 2014 systematic review of eight trials found a long-term remineralising effect on early lesions compared with placebo, but no clear difference from fluoride, and unclear added benefit with fluoride. A 2022 review and meta-analysis of 26 trials in children found calcium phosphate plus fluoride did better than fluoride alone for white spot lesion regression (risk ratio 1.56, 95% CI 1.27 to 1.91), but rated the evidence low certainty. A second, 2024 meta-analysis of CPP-ACP was retracted and is not used.8,9
Food additive E341 (mono-, di- and tri-calcium phosphate)TraditionalNot a remedy. Tri-calcium phosphate is named as a common calcium source for fortifying foods. EFSA's 2019 re-evaluation of phosphate additives (E338 to E341, E343, E450 to E452) found no concern for genotoxicity or carcinogenicity and set a group acceptable daily intake of 40 mg of phosphorus per kg body weight per day. It noted that exposure from the whole diet exceeded this for infants, toddlers and other children at average intake and for adolescents at high intake, and that food supplements alone can exceed it. The US lists calcium phosphate as generally recognised as safe when used in accordance with good manufacturing practice.1,10,2
Phosphate load in kidney disease (harm signal)LimitedPhosphate from additives is absorbed more fully than phosphate in natural foods, and a 2025 review says phosphate intake is worth limiting when kidney function is impaired, though there is no clear evidence to limit it in the general population. In a randomised trial of 134 people on haemodialysis, replacing additive-containing processed foods with additive-free foods cut serum phosphorus from 7.2 to 5.0 mg/dL over 3 months, against 7.1 to 6.7 in the control group. A 2017 review says evidence for restricting phosphate additives in early kidney disease is limited. These studies are about additive phosphates in food, not calcium phosphate supplements specifically; we found no trial of the supplement in kidney disease.5,6,7

How much

Ranges below are what studies used and what supplements commonly contain. They are not a recommendation for you. Start at the low end.

Most elemental calcium at one time
500 mg2
A 2007 review gives this as the maximum dose to take at one time for any calcium supplement. Check the label for elemental calcium, not the weight of the salt.
Calcium dose used in a salt comparison
800 mg elemental calcium4
This was the amount of calcium, as phosphate, carbonate, citrate and other salts, given with iron in a 27-woman trial of iron absorption. It is a research dose, not a recommendation.
EU acceptable intake, all phosphates
40 mg phosphorus per kg body weight a day1
EFSA's group acceptable daily intake for phosphate additives, expressed as phosphorus. It is a ceiling for additives across the whole diet, not a target.
Timing · We found no source on timing for calcium phosphate. A 2007 review advises taking calcium carbonate with a meal and says citrate can be taken without food; it does not give timing for phosphate.With food? · No phosphate-specific source. For CPP-ACP tooth mousse, follow the product label: we did not find a timing or frequency protocol we could cite.How long to trial · Calcium supplement effects on bone are judged over years, not weeks. For white spot lesions, the trials in the 2014 review followed people for 3 to 24 months.

How people take it

Tri-calcium phosphate supplementCheck elemental calcium on the labelSold as tablets or capsules, sometimes with vitamin D. The most-studied calcium supplements are carbonate and citrate, so there is less evidence for this form.
Hydroxyapatite (microcrystalline) supplementVaries by productA calcium phosphate form. A 2007 review found research limited and did not recommend it.
CPP-ACP tooth mousse or pasteTopical, per product labelCasein phosphopeptide with amorphous calcium phosphate, applied to teeth. Not the same as swallowing a calcium phosphate tablet.
Food additive E341 and fortified foodsEU group limit 40 mg phosphorus per kg a dayNot a remedy. See the food additive use above.

Safety

Who should avoid
  • Kidney disease — phosphate intake matters; ask your kidney team before supplements
  • Heavy processed-food diets or other phosphate supplements — EFSA found intakes can exceed the limit
  • Children and adolescents — EFSA found additive phosphate exposure above its limit
Known interactions
No interactions in our data. Absence of a flag is not clearance.

Questions people ask

What are the side effects of calcium phosphate?

We found no trial reporting side effects of calcium phosphate supplements specifically. A 2007 review lists gastrointestinal complaints as the usual adverse effect of calcium supplements. The added concern is phosphate: EFSA found that supplements can push phosphate intake above its acceptable daily intake, and a 2025 review says phosphate intake is worth limiting when kidney function is impaired.

Is calcium phosphate better than calcium carbonate?

We could not show it is. A 2007 review names carbonate and citrate as the standard supplement forms and did not recommend hydroxyapatite because research is limited. The one head-to-head comparison we opened was a laboratory digestion model in which tri-calcium phosphate was absorbed less well than carbonate. Calcium carbonate also has far more trial evidence; see the calcium carbonate entry.

What is calcium phosphate used for?

As a calcium supplement, as the food additive E341 (used in fortified foods), and in the form CPP-ACP in tooth mousse for early enamel lesions. The tooth use has mixed evidence: one review found an effect against placebo but no clear edge over fluoride, and a larger review rated the evidence low certainty.

Is E341 safe to eat?

EFSA re-evaluated it in 2019 and found no concern about genotoxicity or cancer, and set an acceptable intake of 40 mg phosphorus per kg body weight a day for all phosphate additives combined. Its concern was that children's average intake can exceed that, and that supplements can too. The Panel did not address kidney disease in the abstract we read.

Sources

  1. Regulator opinion EFSA Panel on Food Additives and Flavourings (FAF). Re-evaluation of phosphoric acid-phosphates - di-, tri- and polyphosphates (E 338-341, E 343, E 450-452) as food additives and the safety of proposed extension of use. EFSA Journal. 2019.
  2. Review Straub DA. Calcium supplementation in clinical practice: a review of forms, doses, and indications. Nutr Clin Pract. 2007.
  3. Laboratory study Nieto JA, Soriano-Romani L, Tomas-Cobos L, Sharma L, Budde T. Improved in vitro bioavailability of a newly developed functionalized calcium carbonate salt as a food ingredient and its comparison with available commercial calcium salts. Food Chem. 2021.
  4. Randomised trial Candia V, Rios-Castillo I, Carrera-Gil F, et al. Effect of various calcium salts on non-heme iron bioavailability in fasted women of childbearing age. J Trace Elem Med Biol. 2018.
  5. Review Cupisti A, Giannese D, Cozzolino M, Panichi V, D'Alessandro C, Gallieni M. Dietary Phosphorus and Metabolic Health in CKD and ESKD. Clin J Am Soc Nephrol. 2025.
  6. Review St-Jules DE, Goldfarb DS, Pompeii ML, Sevick MA. Phosphate Additive Avoidance in Chronic Kidney Disease. Diabetes Spectr. 2017.
  7. Randomised controlled trial de Fornasari ML, Dos Santos Sens YA. Replacing Phosphorus-Containing Food Additives With Foods Without Additives Reduces Phosphatemia in End-Stage Renal Disease Patients: A Randomized Clinical Trial. J Ren Nutr. 2017.
  8. Systematic review Li J, Xie X, Wang Y, et al. Long-term remineralizing effect of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on early caries lesions in vivo: a systematic review. J Dent. 2014.
  9. Systematic review and meta-analysis Singal K, Sharda S, Gupta A, et al. Effectiveness of Calcium Phosphate derivative agents on the prevention and remineralization of caries among children: a systematic review and meta-analysis of randomized controlled trials. J Evid Based Dent Pract. 2022.
  10. Regulation US Code of Federal Regulations. 21 CFR 182.1217 Calcium phosphate. Substances generally recognized as safe.

Reader notes

Experiences and questions from readers, read by an editor before they appear. They are personal accounts, not evidence, and are not medical advice.

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Last reviewed 30 September 2026 · Next review March 2027 · How we rate evidence