Calcium acetate

MineralCalcium saltBest with a meal

What is it

Calcium acetate is the calcium salt of acetic acid, used both as a calcium source in some supplements and as a prescription phosphate binder (PhosLo, Eliphos) in chronic kidney disease.

Evidence for 2 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Phosphate control in CKD

Strong Evidence

Calcium acetate is FDA-approved as a phosphate binder for kidney disease patients on dialysis.

Calcium supplementation

Limited Evidence

Provides elemental calcium similarly to other organic calcium salts.

How it works

When taken with meals, calcium acetate binds dietary phosphate in the GI tract, forming insoluble calcium phosphate that is excreted. This reduces phosphate absorption and is the primary mechanism for its use in chronic kidney disease patients who cannot adequately excrete phosphate. The calcium portion provides about 25% elemental calcium by weight, comparable to other calcium salts. Calcium absorption from acetate is moderate, similar to other organic salts.

Dosage

For phosphate binding (prescription use): 1334-2668 mg (calcium acetate) with each meal. For calcium supplementation: variable; typically lower doses, with elemental calcium content noted.

When and how to take it

WHEN: With meals to maximize phosphate binding (for kidney patients) or for calcium absorption. HOW: Swallow whole or chew per product form.

2 commercial forms

Compare the main delivery options and what they’re best suited for.

Calcium acetate (prescription PhosLo)

Used as phosphate binder in CKD.

25% elemental calcium

Calcium acetate (supplement)

Less common supplement form.

Same calcium content

Safety

Common side effects include constipation, hypercalcemia (especially in CKD), nausea. Risk of vascular calcification with prolonged high-dose use, particularly in CKD patients.

Who should be cautious

Risk of hypercalcemia in CKD - use only under nephrologist supervision in renal disease. Avoid in hypercalcemia. Pregnancy/lactation: stay within calcium AI when used as supplement.

Interactions

Reduces absorption of tetracyclines, fluoroquinolones, levothyroxine, bisphosphonates, iron supplements; separate by 2-4 hours. Avoid combination with other calcium-based phosphate binders.

Frequently asked questions

Is calcium acetate a drug or supplement?⌄

Both, depending on use. As a phosphate binder for CKD, it is a prescription drug. As a calcium supplement, it is sold OTC.

How much elemental calcium is in calcium acetate?⌄

About 25% by weight. So 1000 mg calcium acetate provides about 250 mg elemental calcium.

References

Calcium acetate on Wikidata — Wikidata link

Calcium acetate (ChEBI:3310) — ChEBI link

Calcium acetate (PubChem CID 6116) — PubChem link

Calcium acetate on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Calcium acetate (PubMed search) — PubMed link

Track Calcium acetate with Pilora

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.