Recommended Dosage of Calcium Carbonate and Citrate-Vitamin D3 Tablet
For optimal calcium and vitamin D3 supplementation, the recommended dosage is 600 mg of calcium (as calcium carbonate or citrate) and 500 IU (12.5 mcg) of vitamin D3 per tablet, taken twice daily for a total daily intake of 1200 mg calcium and 1000 IU vitamin D3.
Calcium Supplementation Guidelines
- The National Osteoporosis Foundation (NOF) recommends a total daily calcium intake of at least 1000 mg for individuals under 50 years without major osteoporosis risk factors, and at least 1200 mg daily for those older than 50 years 1
- For optimal absorption, calcium supplements should be taken in divided doses of no more than 600 mg at a time 1
- The safe upper limit of calcium set by the National Academy of Sciences is 2500 mg per day 1
- Calcium carbonate requires gastric acid for optimal absorption and should be taken with food 1
- Calcium citrate does not require gastric acid for absorption and can be taken between meals, making it the preferred option for patients receiving proton pump inhibitors 1
- Calcium citrate has approximately 24% better absorption than calcium carbonate, independent of intake with meals 2
Vitamin D3 Supplementation Guidelines
- The NOF recommends 800 to 1000 IU of vitamin D per day for adults aged 50 and older 1
- Vitamin D plays a major role in gastrointestinal calcium absorption and is essential for maintaining normal bone mineralization 1
- Vitamin D supplementation increases bone mineral density and reduces the risk of falls (possibly by improving balance) 1
- For bone health, vitamin D should ideally be supplemented in amounts sufficient to bring serum 25(OH)D levels to 30 ng/ml (75 nmol/L) or higher 1
- Vitamin D3 (cholecalciferol) is more effective than vitamin D2 (ergocalciferol) in raising and maintaining 25(OH)D concentrations when longer dosing intervals are employed 1
Specific Populations and Considerations
- For postmenopausal women, the U.S. Preventive Services Task Force (USPSTF) concludes that there is insufficient evidence to assess the balance of benefits and harms of daily supplementation with greater than 400 IU of vitamin D3 and greater than 1000 mg of calcium for the primary prevention of fractures 1
- The USPSTF recommends against daily supplementation with 400 IU or less of vitamin D3 and 1000 mg or less of calcium for the primary prevention of fractures in noninstitutionalized postmenopausal women 1
- For bariatric surgery patients, higher doses of vitamin D3 supplementation (2000-4000 IU daily) may be required 1
- For patients with vitamin D deficiency (serum 25(OH)D levels below 30 ng/mL), a common regimen is prescription vitamin D 50,000 IU weekly for 8 weeks, followed by maintenance therapy 1
Clinical Efficacy and Outcomes
- Studies have shown that combined calcium and vitamin D supplementation moderately reduces bone loss measured in the femoral neck, spine, and total body over a three-year period and reduces the incidence of nonvertebral fractures 3
- Splitting the daily calcium and vitamin D dose provides a more prolonged decrease in serum parathyroid hormone levels than administering the same total amount as a single morning dose 4
- In older patients, vitamin D alone appears as effective as combined calcium/vitamin D treatment in restoring serum vitamin D levels 5
Potential Adverse Effects and Precautions
- Calcium supplementation may increase the risk of kidney stones in susceptible individuals 1
- For patients at risk for nephrolithiasis, increasing dietary calcium from food has been associated with lower risk compared with calcium supplements 1
- Do not exceed 5 chewable calcium carbonate tablets in a 24-hour period, or use the maximum dosage for more than 2 weeks, except under medical supervision 6
- Constipation may occur with calcium supplementation 6
- Iron and calcium supplements should be taken 1-2 hours apart to avoid affecting absorption of each 1