Calcium Supplements: Benefits, Dosage and Safety
Calcium supplements fill a gap when you don't get enough calcium from dairy, fortified foods or leafy greens. Together with vitamin D, they may modestly lower fracture risk in older adults at risk. Get as much as you can from food, and keep supplement doses to 500 mg or less at a time.
Evidence at a glance
| Use | Grade | What the research shows |
|---|---|---|
| Bone health with vitamin D in older adults | B | Modest fracture reduction in people at risk. |
| Preventing fractures in healthy adults | C | Benefit is small or unclear when diet is adequate. |
A: strong, consistent human evidence · B: moderate · C: limited or mixed · D: good evidence of no benefit.
About 99% of your body's calcium is in bones and teeth. Your body takes it from bone when intake is low.
How to take it
Calcium carbonate is cheapest and best taken with food; calcium citrate absorbs well with or without food. Count calcium from food first, then supplement only the gap. See bone health supplements.
Safety and interactions
High intakes can cause constipation and may raise kidney stone risk. Calcium blocks absorption of iron, levothyroxine and some antibiotics, so space them apart.
Always tell your doctor and pharmacist about the supplements you take. Check combinations with our interaction checker.
Sources
This page is for education and is not a substitute for advice from your doctor. Read our medical disclaimer.