← All supplements
Moderate evidenceJoints & skin

Bone Support Formulas

Combinations of calcium, vitamin D, vitamin K2 and trace minerals. Calcium plus vitamin D together does modestly reduce fractures; the added minerals and K2 have thinner support, and vitamin D alone does little.

Where to buy

View on iHerb

Ships to 180+ countries · welcome discount for new customers

Referral link — this site may earn a commission on purchases.

What the science says

  • Fracture prevention from calcium plus vitamin D Moderate evidence

    A 2026 BMJ systematic review and meta-analysis of randomized trials found that combined calcium and vitamin D supplementation reduced total and hip fractures, while vitamin D alone showed no clear fracture benefit. Absolute risk reductions were small and largest in older adults with low intakes or institutional care.

  • Vitamin K2 (MK-7) and bone loss Limited evidence

    A three-year randomized trial in healthy postmenopausal women found that 180 µg/day of MK-7 slowed the age-related decline in bone mineral density at the spine and femoral neck. The effect was modest, the trial was single-centre, and fracture outcomes were not measured.

Dosage & safety

Studied doseTrial-based amounts are roughly 500–1,200 mg/day of elemental calcium (from diet plus supplement) with 800–1,000 IU of vitamin D, and 180 µg/day of MK-7 where K2 is included. Split calcium into doses of 500 mg or less for absorption.
SafetyCalcium supplements can cause constipation and kidney stones, and doses above needs offer no extra benefit; the cardiovascular signal from high-dose calcium remains debated. Vitamin K2 interferes with warfarin and similar vitamin K antagonists — do not take it on those drugs without medical supervision. People with hypercalcaemia, sarcoidosis or kidney disease need medical advice before supplementing.

How to take it

TimingSplit calcium into doses of 500 mg or less, morning and evening — larger single doses are absorbed proportionally worse.
With food?Take it with meals: calcium carbonate needs stomach acid to dissolve, and the vitamin D and K2 need dietary fat.
Worth knowingCount the calcium you already eat — most people get 500 to 700 mg a day from food, and the target is total intake, not supplement intake.

Interactions

With medications

  • levothyroxine

    Calcium binds levothyroxine in the gut and can destabilise a settled thyroid dose. separate by at least 4 hours

  • tetracycline and quinolone antibiotics

    Calcium and magnesium chelate these antibiotics and sharply reduce their absorption. take the antibiotic 2 hours before or 4 to 6 hours after

  • warfarin and other vitamin K antagonists

    The vitamin K2 in these blends directly opposes the drug's mechanism. do not take a K2-containing formula without medical supervision

  • bisphosphonates

    Calcium blocks absorption of oral bisphosphonates. take the bisphosphonate on an empty stomach and separate calcium by at least 2 hours

  • thiazide diuretics

    Thiazides reduce calcium excretion, so supplemental calcium on top can push blood calcium too high. have calcium levels checked rather than supplementing blind

With other supplements

  • iron supplements

    Calcium competes with iron for absorption when taken together. separate by at least 2 hours

  • zinc supplements

    High calcium intake reduces zinc absorption. separate by at least 2 hours

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Do calcium and vitamin D supplements prevent fractures?

Yes, modestly: a 2026 BMJ meta-analysis of randomized trials found combined calcium and vitamin D reduced total and hip fractures, a moderate-grade finding. Vitamin D alone showed no clear benefit, and absolute reductions were small and largest in older adults with low intakes or in care.

Does vitamin K2 in bone supplements help bone density?

The evidence is limited: a three-year trial in postmenopausal women found 180 mcg/day of MK-7 slowed bone density loss at the spine and femoral neck, but the effect was modest and fractures were not measured.

How much calcium and vitamin D should a bone formula have?

Trial-based amounts are roughly 500–1,200 mg/day of elemental calcium from diet plus supplement, with 800–1,000 IU of vitamin D. Most people get 500 to 700 mg a day from food, so count that first, and split supplemental calcium into doses of 500 mg or less with meals.

Can I take a bone support supplement with warfarin or thyroid medication?

Not without medical supervision if the bone formula contains vitamin K2, which directly opposes warfarin. Calcium also binds levothyroxine, so separate them by at least 4 hours, and it blocks bisphosphonates and some antibiotics.

Scientific references

Related in Joints & skin