Remedy · nutrient

Calcium

Also: calcium carbonate, calcium citrate

The main bone mineral — most useful for fractures alongside vitamin D in older or deficient people.

Evidence by condition

Each grade reflects the research for Calcium and that condition specifically.

B
Osteoporosis
With vitamin D, calcium reduces hip (~30%) and total fractures in older or institutionalized adults, though the benefit is small or absent in healthy community-dwellers; calcium alone raises bone density only ~1–2%.
3 citation s
- Calcium plus vitamin D supplementation and risk of fractures: an updated meta-analysis from the National Osteoporosis Foundation
  Meta-analysis 2016 · n=30,970 · Osteoporosis International · PMID 26510847 · DOI 10.1007/s00198-015-3386-5
- Association Between Calcium or Vitamin D Supplementation and Fracture Incidence in Community-Dwelling Older Adults: A Systematic Review and Meta-analysis
  Meta-analysis 2017 · n=51,145 · JAMA · PMID 29279934 · DOI 10.1001/jama.2017.19344
- Calcium intake and bone mineral density: systematic review and meta-analysis
  Meta-analysis 2015 · BMJ · PMID 26420598 · DOI 10.1136/bmj.h4183

Dietary calcium is preferable where possible. As a supplement it earns its keep mainly with vitamin D in older or deficient people; on its own it nudges bone density only slightly and is not adequate osteoporosis therapy.

What researchers studied

These describe how the remedy was used in studies — not a dose or a recommendation.

Form studied: calcium carbonate or citrate (with vitamin D)
Amounts in trials: ~1,000–1,200 mg/day total intake in trials
Notes: Total intake from diet plus supplements is generally kept under ~2,000–2,500 mg/day.

Safety

Likely safe in pregnancy

Interactions: reduces absorption of tetracycline/quinolone antibiotics and levothyroxine (separate dosing)
Contraindications: history of calcium kidney stones or hypercalcemia (seek advice first)
Side effects: constipation
bloating
a debated cardiovascular signal at high supplemental doses

Safety data is not exhaustive. Always check with a clinician or pharmacist before combining remedies or medications.

Known interactions

Levothyroxine (moderate)
Calcium binds levothyroxine in the gut and reduces its absorption — separate doses by several hours.
Ciprofloxacin (moderate)
Calcium binds fluoroquinolone antibiotics and reduces their absorption — separate dosing.
Doxycycline (moderate)
Calcium binds tetracycline antibiotics and reduces their absorption — separate dosing.