Are calcium tablets safe?

Safety of Calcium Tablets

Calcium tablets are generally safe when taken within recommended dosage limits, but they should be obtained from dietary sources when possible to minimize potential side effects and cardiovascular risks.

Recommended Calcium Intake

The safety of calcium tablets depends on several factors including total daily intake, formulation, and individual health factors:

• Recommended daily intake 1, 2:

  • Women >50 years and men >70 years: 1200 mg/day
  • Adults 19-50 years and men 51-70 years: 1000 mg/day
  • Upper intake level (should not exceed): 2000-2500 mg/day

• Preferred sources of calcium 1:

  • Dietary sources are preferred over supplements
  • Aim for approximately 300 mg from non-dairy sources and 740-900 mg from dairy products
  • Supplements should only be considered when dietary intake is inadequate

Safety Considerations and Side Effects

Common Side Effects

• Gastrointestinal symptoms 1, 2:
  • Constipation (most common)
  • Bloating
  • Gas

Potential Risks

1. Kidney stones 1, 2:

   • Increased risk with supplement use but not with dietary calcium
   • Risk is dose-dependent

2. Cardiovascular concerns 1, 2, 3:

   • Some studies suggest a potential 20% increased risk of myocardial infarction with calcium supplements
   • Evidence remains inconsistent and inconclusive
   • This risk appears associated with supplements but not dietary calcium

3. Medication interactions 2:

   • Calcium can interfere with absorption of certain medications
   • Can compete with iron absorption
   • May interact with certain antibiotics and thyroid medications

Optimizing Safety of Calcium Supplements

If dietary intake is insufficient and supplements are necessary:

1. Choose appropriate formulation 1, 2, 4:

   • Calcium carbonate: 40% elemental calcium, most cost-effective, take with meals
   • Calcium citrate: 21% elemental calcium, better absorbed without food, preferred for those on acid-reducing medications

2. Proper dosing 1, 2, 4:

   • Take in divided doses of ≤500 mg elemental calcium at a time
   • Improves absorption and reduces side effects
   • Take calcium carbonate with meals to enhance absorption

3. Quality assurance 4:

   • Choose USP-verified supplements to ensure quality and purity
   • Avoid bone meal, oyster shell, or dolomite supplements (may contain lead)

4. Monitoring 2:

   • Track total calcium intake (diet plus supplements)
   • Be vigilant about side effects, especially in high-risk individuals

High-Risk Populations

Exercise additional caution with calcium supplements in:

• People with history of kidney stones
• Those with hypercalcemia or hypercalciuria
• Patients with significant cardiovascular disease
• People taking thiazide diuretics or with renal impairment (risk of milk-alkali syndrome) 5
• Those taking proton pump inhibitors (absorption concerns) 2

Bottom Line

For optimal safety:

1. Prioritize dietary sources of calcium whenever possible
2. If supplements are needed, don't exceed 500 mg elemental calcium per dose
3. Keep total daily calcium intake (diet plus supplements) below 2000 mg
4. Consider calcium citrate for those with digestive issues or on acid-reducing medications
5. Take calcium carbonate with meals to optimize absorption