Disclosure: We earn commissions on purchases made through our links. This never influences our scores. Editorial policy
Calcium + Vitamin D3
Calcium combined with Vitamin D3 is one of the most studied supplement combinations in medicine - and one where the evidence has shifted significantly in the last decade. For fracture prevention in institutionalized elderly, the evidence is strong.
- Evidence
- Strong Evidence
- Category
- Vitamins & Minerals
- Best form
- Calcium Citrate (does not require stomach acid, well-absorbed on an empty stomach)
- Effective dose
- 1,000-1,200mg elemental calcium daily + 400-1,000 IU Vitamin D3
- Lab tested
- 2 of 10 products
- Category
- Vitamins & Minerals
- Best form
- Calcium Citrate (does not require stomach acid, well-absorbed on an empty stomach)
- Effective dose
- 1,000-1,200mg elemental calcium daily + 400-1,000 IU Vitamin D3
- Lab tested
- 2 of 10 products
What Is Calcium + Vitamin D3?
Calcium combined with Vitamin D3 is one of the most studied supplement combinations in medicine - and one where the evidence has shifted significantly in the last decade.
For fracture prevention in institutionalized elderly, the evidence is strong. The landmark Chapuy 1992 trial in 3,270 nursing home residents showed 43% fewer hip fractures over 18 months. A 2007 meta-analysis of 63,897 people confirmed a 12% overall fracture reduction and 30% hip fracture reduction when compliance was high and doses reached at least 1,200mg calcium plus 800 IU D3.
For community-dwelling healthy adults, the picture is different. The USPSTF issued a "D" grade recommendation against daily supplementation with 400 IU or less of D3 and 1,000mg or less of calcium for primary fracture prevention in postmenopausal women - meaning these lower doses showed no net benefit while still carrying kidney stone risk. For higher doses, the evidence was insufficient to make a recommendation.
Cardiovascular safety is a real concern. A 2010 meta-analysis (Bolland et al., 11,900+ participants) linked calcium supplements to a 27% increased MI risk. A more rigorous 2021 meta-analysis (Myung et al., 43,000+ participants in double-blind RCTs) confirmed a 15% increase in CVD and 16% increase in coronary heart disease. The risk appears dose-dependent: supplemental boluses at or above 1,000mg/day significantly amplified cardiovascular risk, while dietary calcium up to 1,000mg/day was safe.
One area of strong benefit: preeclampsia prevention. The WHO recommends 1.5-2.0g daily calcium for pregnant women in low-calcium populations, based on Cochrane data showing a 55% reduction in preeclampsia risk.
A Cochrane review of 18 RCTs (3,140 participants) found calcium supplementation produces small but statistically significant reductions in blood pressure: systolic -1.37 mmHg, diastolic -1.45 mmHg, at 1,000-1,500mg/day. This effect is real but too small for calcium to serve as a standalone treatment for hypertension.
Absorption is maximized when calcium is taken in doses of 500mg or less at a time. Calcium carbonate requires stomach acid and should be taken with food, while calcium citrate can be taken on an empty stomach and is better for people with low stomach acid or those taking proton pump inhibitors.
Does It Work? The Evidence
Preserves bone mineral density in postmenopausal women and older adults
SupportedWomen's Health Initiative (n=36,282, PMID: 16481635): consistently showed reduced rate of bone loss at the hip with calcium + D3 supplementation
Reduces fracture risk
ConflictedTang et al. 2007 meta-analysis (PMID: 17720017, n=63,897): 12% overall fracture reduction (SRRE 0.85, 95% CI 0.73-0.98), 30% hip fracture reduction (SRRE 0.70, 95% CI 0.56-0.87); therapeutic threshold: minimum 1,200mg calcium + 800 IU D3. Chapuy 1992 (PMID: 1331788): 43% fewer hip fractures (P=0.043) and 32% fewer nonvertebral fractures (P=0.015) in 3,270 nursing home residents (mean age 84); PTH fell 44%, serum 25(OH)D increased 162%. BUT: USPSTF 2018 (PMID: 29677309) issued a 'D' grade against low-dose supplementation (<=400 IU D3/<=1,000mg calcium) for community-dwelling postmenopausal women
Does NOT increase cardiovascular or heart attack risk
IneffectiveBolland et al. 2010 meta-analysis (PMID: 20671013): RR 1.27 (95% CI 1.01-1.59) for MI using trial-level data; HR 1.31 (95% CI 1.02-1.67) using patient-level data, with calcium supplements >=500mg/day. Myung et al. 2021 (PMID: 33530332, 43,000+ participants in double-blind RCTs): 15% increased CVD risk (RR 1.15, 95% CI 1.06-1.25) and 16% increased CHD risk (RR 1.16, 95% CI 1.05-1.28), specifically in healthy postmenopausal women at supplemental doses >=1,000mg/day. Critical dose-response finding: dietary calcium up to 1,000mg/day is safe, but supplemental boluses at or above 1,000mg/day trigger rapid serum calcium spikes that drive risk. WHI subgroup analysis: women not previously using calcium supplements who were newly randomized to calcium+D3 experienced increased cardiovascular events; women already taking supplements at baseline did not - suggesting chronic adaptation vs. bolus spike as the key mechanistic variable.
Prevents preeclampsia in pregnant women with low calcium intake
SupportedCochrane Review (Hofmeyr et al., updated 2025, PMID: 41330480, n=18,000+): high-dose calcium (>=1g/day) reduced preeclampsia risk by 55% (RR 0.45, 95% CI 0.31-0.65); protective effect stronger in highest-risk women (average RR 0.22). Also reduced maternal death or serious morbidity (RR 0.80, 95% CI 0.66-0.98) and preterm birth (RR 0.76, 95% CI 0.60-0.97). Low-dose regimens (<1g/day) also showed benefit (RR 0.38, 95% CI 0.28-0.52). WHO 2013 guideline (PMID: 24006556) recommends 1.5-2.0g/day divided into 3-4 doses for at-risk pregnancies
Reduces colorectal cancer risk
IneffectiveWHI trial (n=36,282): 1,000mg calcium + 400 IU D3 vs placebo; 11.1-year follow-up found HR 0.95 (95% CI 0.80-1.13) - no benefit for colorectal cancer incidence
Modestly reduces blood pressure in general population
Early SignalCochrane review (Cormick et al., 18 RCTs, n=3,140): calcium supplementation reduced systolic BP by mean -1.37 mmHg and diastolic BP by mean -1.45 mmHg at 1,000-1,500mg/day. High-certainty GRADE evidence. Males showed greater reductions (systolic MD -2.14 mmHg) than females (systolic MD -1.25 mmHg). Despite the small individual effect, a population-level 2 mmHg downward shift is estimated to predict ~10% lower stroke mortality and ~7% lower ischemic heart disease mortality. Effect size is too small for calcium to serve as standalone hypertension monotherapy.
| Claimed Benefit | Key Studies | Our Verdict |
|---|---|---|
| Preserves bone mineral density in postmenopausal women and older adults | Women's Health Initiative (n=36,282, PMID: 16481635): consistently showed reduced rate of bone loss at the hip with calcium + D3 supplementation | Supported |
| Reduces fracture risk | Tang et al. 2007 meta-analysis (PMID: 17720017, n=63,897): 12% overall fracture reduction (SRRE 0.85, 95% CI 0.73-0.98), 30% hip fracture reduction (SRRE 0.70, 95% CI 0.56-0.87); therapeutic threshold: minimum 1,200mg calcium + 800 IU D3. Chapuy 1992 (PMID: 1331788): 43% fewer hip fractures (P=0.043) and 32% fewer nonvertebral fractures (P=0.015) in 3,270 nursing home residents (mean age 84); PTH fell 44%, serum 25(OH)D increased 162%. BUT: USPSTF 2018 (PMID: 29677309) issued a 'D' grade against low-dose supplementation (<=400 IU D3/<=1,000mg calcium) for community-dwelling postmenopausal women | Conflicted |
| Does NOT increase cardiovascular or heart attack risk | Bolland et al. 2010 meta-analysis (PMID: 20671013): RR 1.27 (95% CI 1.01-1.59) for MI using trial-level data; HR 1.31 (95% CI 1.02-1.67) using patient-level data, with calcium supplements >=500mg/day. Myung et al. 2021 (PMID: 33530332, 43,000+ participants in double-blind RCTs): 15% increased CVD risk (RR 1.15, 95% CI 1.06-1.25) and 16% increased CHD risk (RR 1.16, 95% CI 1.05-1.28), specifically in healthy postmenopausal women at supplemental doses >=1,000mg/day. Critical dose-response finding: dietary calcium up to 1,000mg/day is safe, but supplemental boluses at or above 1,000mg/day trigger rapid serum calcium spikes that drive risk. WHI subgroup analysis: women not previously using calcium supplements who were newly randomized to calcium+D3 experienced increased cardiovascular events; women already taking supplements at baseline did not - suggesting chronic adaptation vs. bolus spike as the key mechanistic variable. | Ineffective |
| Prevents preeclampsia in pregnant women with low calcium intake | Cochrane Review (Hofmeyr et al., updated 2025, PMID: 41330480, n=18,000+): high-dose calcium (>=1g/day) reduced preeclampsia risk by 55% (RR 0.45, 95% CI 0.31-0.65); protective effect stronger in highest-risk women (average RR 0.22). Also reduced maternal death or serious morbidity (RR 0.80, 95% CI 0.66-0.98) and preterm birth (RR 0.76, 95% CI 0.60-0.97). Low-dose regimens (<1g/day) also showed benefit (RR 0.38, 95% CI 0.28-0.52). WHO 2013 guideline (PMID: 24006556) recommends 1.5-2.0g/day divided into 3-4 doses for at-risk pregnancies | Supported |
| Reduces colorectal cancer risk | WHI trial (n=36,282): 1,000mg calcium + 400 IU D3 vs placebo; 11.1-year follow-up found HR 0.95 (95% CI 0.80-1.13) - no benefit for colorectal cancer incidence | Ineffective |
| Modestly reduces blood pressure in general population | Cochrane review (Cormick et al., 18 RCTs, n=3,140): calcium supplementation reduced systolic BP by mean -1.37 mmHg and diastolic BP by mean -1.45 mmHg at 1,000-1,500mg/day. High-certainty GRADE evidence. Males showed greater reductions (systolic MD -2.14 mmHg) than females (systolic MD -1.25 mmHg). Despite the small individual effect, a population-level 2 mmHg downward shift is estimated to predict ~10% lower stroke mortality and ~7% lower ischemic heart disease mortality. Effect size is too small for calcium to serve as standalone hypertension monotherapy. | Early Signal |
How to Choose: Forms, Doses & What Matters
Clinical dose: 1,000-1,200mg elemental calcium daily + 400-1,000 IU Vitamin D3; divide calcium into 500mg doses for better absorption
Best forms: Calcium Citrate (does not require stomach acid, well-absorbed on an empty stomach), Di-Calcium Malate, Calcium Bisglycinate
Calcium carbonate must be taken with food to ensure adequate stomach acid for absorption. Calcium citrate can be taken with or without food, making it the preferred form for individuals with low stomach acid, those on proton pump inhibitors, and bariatric surgery patients (calcium carbonate is poorly absorbed in achlorhydric environments). Critically, divide doses so you take no more than 500mg of elemental calcium at one time - absorption efficiency drops significantly above this amount. Take Vitamin D3 with a meal containing fat for best absorption.
Who Should Take Calcium + Vitamin D3?
Postmenopausal women with osteopenia or osteoporosis, as this population has the strongest evidence base. Individuals with diagnosed vitamin D deficiency and low dietary calcium intake. Institutionalized older adults at high risk for falls and fractures. Those who do not consume adequate dairy or calcium-rich foods in their diet. Pregnant women in populations with low dietary calcium intake, where 1.5-2.0g daily is WHO-recommended for preeclampsia prevention.
Who Should Avoid It?
Individuals with a history of calcium-oxalate kidney stones, as supplemental calcium may increase stone risk (the USPSTF identifies this as the most demonstrable harm). Note: calcium citrate is the preferred form for stone-prone individuals, as the citrate molecule inhibits calcium oxalate crystallization in the renal system. Individuals with hypercalcemia or hyperparathyroidism. Those with existing cardiovascular disease or high coronary artery calcium scores should consult their doctor - meta-analyses of 43,000+ participants found supplemental calcium at 1,000mg/day or above associated with a 15-16% increase in cardiovascular and coronary heart disease risk. Dietary calcium sources are preferred over supplements for this population.
Side Effects & Safety
Constipation is the most common side effect, particularly with calcium carbonate - the poor dissociation of carbonate in low-acid environments, combined with interactions with intestinal flora, can cause bloating, flatulence, and obstinate constipation. Bloating and gas are also frequently reported. High-dose calcium supplementation may increase the risk of kidney stones in susceptible individuals; the USPSTF identifies nephrolithiasis as the most demonstrable harm of supplementation. Meta-analyses of 43,000+ participants in double-blind RCTs (Myung et al. 2021) found a 15% increased cardiovascular disease risk at supplemental doses of 1,000mg/day or above in postmenopausal women - this risk is dose-dependent and driven by rapid postprandial serum calcium spikes from bolus supplements, unlike the slow absorption from food. Dietary calcium up to 1,000mg/day does not carry this risk. Taking divided doses (500mg maximum per dose) and choosing citrate over carbonate can minimize both GI and cardiovascular side effects.
Product Scores
10 products scored on dosing accuracy, third-party testing, cost per effective dose, and label transparency.
The Scorecard: 10 Products Compared
Calcium 600 mg with Vitamin D3
Kirkland SignatureUSP Verified quality at the lowest cost per serving of any product tested - exceptional value. Lower D3 dose (400 IU) may require additional supplementation
Prices checked 2026-03-31. Cost shown is per clinically effective daily dose, not per pill.
Calcium 600 mg with Vitamin D3 Tablets
Nature MadeUSP Verified for quality at an excellent price point - uses calcium carbonate which requires taking with food
Prices checked 2026-03-31. Cost shown is per clinically effective daily dose, not per pill.
Calcium 1200mg Plus 1000IU Vitamin D3 Softgels
Nature's Bounty
Provides a full 1200mg dose in one serving, but this exceeds the optimal 500mg single-dose absorption threshold, leading to wasted calcium and higher GI distress risk
Prices checked 2026-03-31. Cost shown is per clinically effective daily dose, not per pill.
Caltrate 600+D3 Calcium and Vitamin D Supplement Tablets
Caltrate
Recognizable legacy brand with good D3 dosing (800 IU) - requires taking with food for calcium carbonate absorption
Prices checked 2026-03-31. Cost shown is per clinically effective daily dose, not per pill.
Calcium 600 mg with Vitamin D3
Spring ValleyExtremely affordable store brand option with high pill count, but lacks third-party purity testing guarantees
Prices checked 2026-03-31. Cost shown is per clinically effective daily dose, not per pill.
Calcium Citrate Plus Vitamin D3
Bluebonnet Nutrition
Provides a full 1000mg clinical dose of calcium citrate per serving, but requires 4 caplets and ideally should be split throughout the day
Prices checked 2026-03-31. Cost shown is per clinically effective daily dose, not per pill.
Calcium Citrate with Vitamin D-3
Best Naturals
Budget-friendly calcium citrate option manufactured in a GMP facility, but lower D3 amount and lacks third-party certification
Prices checked 2026-03-31. Cost shown is per clinically effective daily dose, not per pill.
Citracal Maximum Plus Calcium Citrate + D3
Citracal
Leading calcium citrate brand that does not require food for absorption - ideal for split dosing throughout the day
Prices checked 2026-03-31. Cost shown is per clinically effective daily dose, not per pill.
Calcium Vitamin D Bone Health Joint Supplement Chews
Equate
Chewable form is ideal for those with difficulty swallowing pills, but contains added sugars and lacks heavy metal testing for the cocoa blend
Prices checked 2026-03-31. Cost shown is per clinically effective daily dose, not per pill.
Calcium with Vitamin D3
Pure EncapsulationsPremium hypoallergenic formula using bioavailable forms, but extremely expensive per effective dose due to low per-capsule dosing
Prices checked 2026-03-31. Cost shown is per clinically effective daily dose, not per pill.
Full Comparison
| Category | Calcium 600 mg with Vitamin D3 Kirkland Signature | Calcium 600 mg with Vitamin D3 Tablets Nature Made | Calcium 1200mg Plus 1000IU Vitamin D3 Softgels Nature's Bounty | Caltrate 600+D3 Calcium and Vitamin D Supplement Tablets Caltrate | Calcium 600 mg with Vitamin D3 Spring Valley | Calcium Citrate Plus Vitamin D3 Bluebonnet Nutrition | Calcium Citrate with Vitamin D-3 Best Naturals | Citracal Maximum Plus Calcium Citrate + D3 Citracal | Calcium Vitamin D Bone Health Joint Supplement Chews Equate | Calcium with Vitamin D3 Pure Encapsulations |
|---|---|---|---|---|---|---|---|---|---|---|
| Brand Score | 83/100Winner | 83/100 | 70/100 | 69/100 | 67/100 | 64/100 | 63/100 | 63/100 | 57/100 | 48/100 |
| Dosing & Form | 18/25 | 18/25 | 25/25Winner | 18/25 | 18/25 | 25/25 | 18/25 | 18/25 | 18/25 | 14/25 |
| Purity | 23/25Winner | 23/25 | 13/25 | 13/25 | 13/25 | 13/25 | 13/25 | 13/25 | 7/25 | 13/25 |
| Value | 23/25Winner | 19/25 | 13/25 | 19/25 | 23/25 | 7/25 | 13/25 | 13/25 | 19/25 | 2/25 |
| Transparency | 19/25 | 23/25Winner | 19/25 | 19/25 | 13/25 | 19/25 | 19/25 | 19/25 | 13/25 | 19/25 |
| Cost/Day | $0.05Winner | $0.16 | $0.22 | $0.17 | $0.05 | $0.41 | $0.22 | $0.28 | $0.13 | $0.62 |
| Dose/Serving | 600mg | 600mg | 1200mg | 600mg | 600mg | 1000mg | 630mg | 630mg | 600mg | 300mg |
| Form | Calcium Carbonate, Cholecalciferol | Calcium Carbonate, Cholecalciferol | Calcium Carbonate, Cholecalciferol | Calcium Carbonate, Cholecalciferol | Calcium Carbonate, Cholecalciferol | Calcium Citrate, Cholecalciferol | Calcium Citrate, Cholecalciferol | Calcium Citrate, Cholecalciferol | Calcium Carbonate, Cholecalciferol | Di-Calcium Malate, Calcium Citrate, Cholecalciferol |
| Third-Party Tested | ✓ Yes | ✓ Yes | No | No | No | No | No | No | No | No |
| Proprietary Blend | No | No | No | No | No | No | No | No | Yes | No |
Frequently Asked Questions
What is the difference between calcium carbonate and calcium citrate?
Calcium carbonate is the cheapest and most concentrated form (40% elemental calcium) but requires stomach acid for absorption, so it must be taken with food. Calcium citrate is less concentrated (21% elemental calcium) so the tablets are larger, but it absorbs well without food and is better tolerated by people with low stomach acid or those on acid-reducing medications. Citrate is generally the preferred form for supplementation.
Should I take all my calcium at once?
No. The body can only absorb about 500mg of elemental calcium efficiently at one time. Taking more than 500mg in a single dose wastes the excess and increases the risk of GI side effects. Split your dose into 2-3 servings throughout the day for maximum absorption.
Do I need to supplement calcium if I eat dairy?
It depends on how much dairy you consume. One cup of milk or yogurt provides about 300mg of calcium. If you regularly consume 2-3 servings of dairy daily, you may be meeting the 1,000-1,200mg target through diet alone and may not need supplementation. A food diary can help determine your baseline intake.
How much Vitamin D3 should I take with calcium?
Most clinical trials used 400-1,000 IU of Vitamin D3 alongside calcium. Vitamin D is essential for calcium absorption - without adequate D3, you cannot efficiently absorb supplemental calcium regardless of the form. If you are vitamin D deficient (common in northern latitudes), your doctor may recommend higher D3 doses.
Can calcium supplements cause heart problems?
This is a legitimate concern, not just theoretical. A 2010 meta-analysis of RCTs found calcium supplements associated with a 27% increased MI risk (RR 1.27). A more rigorous 2021 meta-analysis of 43,000+ participants in double-blind RCTs confirmed a 15% increased CVD risk and 16% increased coronary heart disease risk. The risk appears dose-dependent: supplemental boluses of 1,000mg/day or more significantly amplified cardiovascular risk, while dietary calcium up to 1,000mg/day appeared safe. The working hypothesis is that supplement boluses cause rapid serum calcium spikes that promote arterial calcification, unlike slow absorption from food. If you supplement, keep total intake (diet + supplements) at or below 1,200mg/day and prioritize food sources first.
Didn't the USPSTF recommend against calcium + D3 supplementation?
Partially. In 2018, the USPSTF issued a 'D' grade (recommend against) specifically for low-dose supplementation - 400 IU or less of D3 and 1,000mg or less of calcium - for fracture prevention in community-dwelling postmenopausal women. At these doses, they found no net fracture prevention benefit but a real increase in kidney stone risk. For higher doses, the evidence was insufficient to make a recommendation. The USPSTF recommendation does not apply to institutionalized elderly, people with diagnosed osteoporosis, or those with confirmed deficiencies - populations where the evidence for supplementation remains stronger.
Can calcium supplements help prevent preeclampsia during pregnancy?
Yes - this is one of the strongest evidence-backed uses for calcium supplementation. The WHO recommends 1.5-2.0g of elemental calcium daily for pregnant women in populations with low dietary calcium intake. Cochrane reviews of over 15,000 women found high-dose calcium reduced preeclampsia risk by 55%, with even stronger effects in high-risk women. Always consult your OB-GYN before starting supplementation during pregnancy.
Why are some calcium supplements so much cheaper than others?
The main cost drivers are the calcium form (carbonate is cheapest, citrate and malate cost more), whether USP or third-party testing is included, and the amount of Vitamin D3. Budget store brands using calcium carbonate can cost as little as $0.03-0.05 per day, while premium calcium citrate products from practitioner brands can cost $0.40-0.60 per day.
Related Articles
Supplement Scorecard Newsletter
Research worth reading.
New supplement scores and evidence summaries delivered to your inbox.
Sources
- Jackson RD, et al. Calcium plus vitamin D supplementation and the risk of fractures. N Engl J Med. 2006;354(7):669-83. (Women's Health Initiative)
- US Preventive Services Task Force. Vitamin D, Calcium, or Combined Supplementation for the Primary Prevention of Fractures in Community-Dwelling Adults. JAMA. 2018;319(15):1592-1599.
- Bolland MJ, et al. Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. BMJ. 2010;341:c3691.
- Ross AC, et al. The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know. J Clin Endocrinol Metab. 2011;96(1):53-8.
- Myung SK, et al. Calcium Supplements and Risk of Cardiovascular Disease: A Meta-Analysis of Clinical Trials. Nutrients. 2021;13(2):368.
- Tang BM, et al. Use of calcium or calcium in combination with vitamin D supplementation to prevent fractures and bone loss in people aged 50 years and older: a meta-analysis. Lancet. 2007;370(9588):657-666.
- Chapuy MC, et al. Vitamin D3 and calcium to prevent hip fractures in elderly women. N Engl J Med. 1992;327(23):1637-42.
- US Preventive Services Task Force. Vitamin D, Calcium, or Combined Supplementation for the Primary Prevention of Fractures in Community-Dwelling Adults: Recommendation Statement. JAMA. 2018;319(15):1592-1599.
- World Health Organization. Guideline: Calcium Supplementation in Pregnant Women. Geneva: WHO; 2013.
- Hofmeyr GJ, et al. Calcium supplementation during pregnancy for preventing hypertensive disorders and related problems. Cochrane Database Syst Rev. 2018;10:CD001059.
- Hofmeyr GJ, et al. Calcium supplementation during pregnancy for preventing hypertensive disorders and related problems. Cochrane Database Syst Rev. 2025 (updated).
- Cormick G, et al. Calcium supplementation for prevention of primary hypertension. Cochrane Database Syst Rev. 2022.
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. The products discussed on this page are not intended to diagnose, treat, cure, or prevent any disease. Always consult with a qualified healthcare professional before starting any supplement regimen.