Which statement about calcium supplements is correct regarding absorption, dosing, and total daily intake?

• A. Calcium carbonate requires stomach acid and should be taken with meals; calcium citrate can be taken with or without meals; total daily elemental calcium about 1000-1200 mg.
• B. Calcium citrate requires stomach acid for absorption.
• C. Calcium carbonate should be taken on an empty stomach for best absorption.
• D. Total daily calcium should be 2000-3000 mg.

Answer: (A)

Absorption of calcium supplements depends on the salt form and the presence of stomach acid. Calcium carbonate dissolves best when there is stomach acid, so it should be taken with meals when acid production is higher. Calcium citrate does not rely on stomach acid, so it can be taken with or without meals, which is helpful for people with reduced gastric acidity or those on acid-suppressing medications. For most adults, aiming for about 1000–1200 mg of elemental calcium per day from all sources and spreading that amount in divided doses improves absorption. Going up to 2000–3000 mg daily isn’t necessary and can increase the risk of side effects like GI upset or kidney stones.