Is calcium citrate similar to Tums (calcium carbonate) as an antacid?

Is Calcium Citrate an Antacid Like Tums?

No, calcium citrate is not primarily an antacid like Tums (calcium carbonate), though both contain calcium and calcium carbonate does have antacid properties that calcium citrate lacks.

Key Differences Between Calcium Citrate and Calcium Carbonate

Antacid Properties

• Calcium carbonate (Tums) neutralizes stomach acid through its alkaline properties, making it effective for treating heartburn and indigestion 1
• Calcium citrate does not function as an antacid and will not relieve heartburn or acid reflux symptoms 1, 2

Absorption Characteristics

• Calcium citrate absorption is independent of stomach acid, making it the preferred supplement for individuals taking acid-suppressing medications (H2-blockers, proton pump inhibitors) or those with achlorhydria 3, 1
• Calcium carbonate requires stomach acid for optimal absorption and should be taken with meals 1
• Calcium citrate demonstrates superior absorption (39.2%) compared to calcium carbonate (31.2%) when taken on an empty stomach 4

Clinical Applications

• Calcium carbonate is used as:

  • An antacid for symptomatic relief of heartburn 1
  • A phosphate binder in chronic kidney disease 3, 5
  • A calcium supplement (contains 40% elemental calcium) 5

• Calcium citrate is used as:

  • A calcium supplement only (contains 25% elemental calcium) 5
  • The preferred form for patients with reduced stomach acid 3, 1
  • The preferred form for osteoporosis treatment when taken between meals 2

Important Clinical Considerations

• Calcium citrate can be taken without food, which may improve compliance and reduce gastrointestinal side effects like bloating 2
• Calcium carbonate must be taken with meals for optimal absorption 1
• In chronic kidney disease patients, calcium citrate should be avoided as it enhances calcium absorption more than other calcium salts, increasing the risk of hypercalcemia and vascular calcification 5, 6
• The maximum single dose of elemental calcium that should be taken at one time is 500 mg, regardless of the calcium salt used 1

Common Pitfall

Do not assume calcium citrate will provide antacid relief simply because it contains calcium—only calcium carbonate has acid-neutralizing properties 1. If a patient needs both calcium supplementation and antacid relief, calcium carbonate taken with meals serves both purposes, whereas calcium citrate addresses only supplementation needs 1, 2.