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ingestible · for bone health & osteoporosis prevention

Calcium + Vitamin D3 Combined Supplementation

Reviewed by the Nimbera editorial team · Last updated May 2026

Liu et al. 2020 systematic review and meta-analysis of RCTs (Food Funct, PMID 33237064) - combined calcium + vitamin D supplementation significantly increased total BMD (SMD 0.537) and reduced hip fracture incidence by approximately 14% (RR 0.864) in postmenopausal women.$10-$25 per month for combined supplements.

How to use

Take 1,000-1,200 mg of elemental calcium daily (from food and supplements combined) alongside 800-1,000 IU of vitamin D3. Spread calcium doses across the day (no more than 500 mg per dose for best absorption). Calcium carbonate is best taken with food; calcium citrate can be taken anytime.

How it works

Calcium is the primary mineral in hydroxyapatite, the crystalline structure of bone. Vitamin D3 (cholecalciferol) is essential for intestinal calcium absorption and renal calcium reabsorption; without adequate D3, up to 90% of dietary calcium may be lost. Together they support bone matrix mineralisation and reduce compensatory parathyroid hormone-driven bone resorption.

Where to buy

Pharmacies and supermarkets. Common products include Caltrate Plus D, Citracal + D3, and many store brands. Look for products listing elemental calcium content, not total salt weight.

Typical cost: $10-$25 per month for combined supplements.

Safety notes

Do not exceed 2,000 mg elemental calcium daily - excess calcium increases risk of kidney stones and may be associated with cardiovascular risk. Vitamin D toxicity can occur above 4,000 IU/day chronically. People with hypercalcaemia, sarcoidosis, or primary hyperparathyroidism should not supplement without medical supervision. Calcium carbonate can cause constipation.

Drug & supplement interactions

  • Always tell your doctor or pharmacist about any supplements you take.
  • Interactions can occur with prescription medications, blood thinners, and immunosuppressants.
  • Herbal remedies can affect how the body absorbs or metabolises drugs.
  • Check drugs.com interactions checker before starting.

Clinical source

Liu et al. 2020 - Food Funct (PMID 33237064)

This information is compiled from primary clinical literature and is for informational purposes only. It is not a substitute for professional medical advice. Read our full disclaimer.