RDA and TUL for Calcium (milligrams [mg] per day)

 Age
Male RDA (mg)
Female RDA (mg)
TUL (mg)

0-6 months
200
200
1,000

7-12 months
260
260
1,500

1-3 years
700
700
2,500

4-8 years
1,000
1,000
2,500

9-13 years
1,300
1,300
3,000

14-18 years
1,300
1,300
3,000

19-50 years
1,000
1,000
2,500

51-70 years
1,000
1,200
2,000

70 years +
1,200
1,200
2,000

Calcium requirements increase with age and are highest during adolescence and teenage years when bone development is crucial. Pregnancy and lactation do not change calcium requirements.

Supplements are intended to help meet calcium requirements when intake from the diet is low. You do not need to supplement calcium if you meet your calcium needs with food.

Best Dosage for Absorption

Calcium intake and calcium absorption have an inverse relationship. The lower your intake, the more calcium you absorb, and vice versa—the higher your intake, the less calcium you absorb. Therefore, calcium absorption in supplement form is best in doses of 500 mg or less.

Taking calcium supplements in excess of 2,000 mg daily can interfere with the absorption of iron and zinc.

What Are the Benefits of Calcium Supplements?
1. Prevents Calcium Deficiency

Individuals with decreased calcium absorption or insufficient intake through their diet may be at risk of calcium deficiency and may require a supplement. A calcium deficiency can lead to reduced bone strength and osteoporosis.

2. Maintains Bone Health

Calcium supplements likely have a role in maintaining bone health, particularly for those who can’t get enough calcium from food, and those who are already at a higher risk of fracture (e.g., an osteoporosis diagnosis).

Calcium and vitamin D are sometimes supplemented together due to their mutual benefits for bone health. However, research has found mixed results on this pairing. For example:

Bone mineral density (BMD): Most research supports supplementing calcium and vitamin D in older adults improves BMD. However, a 2023 systematic review does not support supplemental calcium and vitamin D for improving BMD in healthy postmenopausal people.
Fracture risk: Results of research on fracture risk are also mixed, with some reviews showing a decrease in fracture risk with supplementation and others not.

According to the U.S. Preventive Services Task Force, the current body of evidence is not sufficient to promote the supplementation of 1,000 mg of calcium and 400 international units (IU) of vitamin D for the primary prevention of fractures in postmenopausal women.

It is important to note that this does not apply to people with the following:

Although not all research supports this, the U.S. Food and Drug Administration (FDA) has approved a health claim for the use of calcium and vitamin D supplements in preventing osteoporosis.

3. Reduces Risk of Preeclampsia

Preeclampsia is high blood pressure that occurs during pregnancy and is a leading cause of maternal and neonatal morbidity and mortality. Calcium supplementation in pregnant people, particularly those with low calcium intakes, reduces the risk of preeclampsia.

It is recommended for pregnant people with low dietary intakes of calcium to take 1,500 mg to 2,000 mg of supplemental calcium.

4. Unproven Uses

Calcium supplementation may be marketed for several other conditions, but the research is not adequate to support routine supplementation for:

What Are the Risks and Safety Precautions?

Taking calcium supplements may have some unintended effects and increase the risk of:

Heart disease: Some studies found an increased risk of heart disease or heart attack with calcium supplementation, while others have not. The National Osteoporosis Foundation and the American Society for Preventive Cardiology reviewed the available research in 2016 and concluded that calcium and vitamin D do not affect heart disease or mortality.
Kidney stones: Higher intakes of calcium may increase the risk of developing kidney stones (mineral and salt deposits that form in the kidneys).
Prostate cancer: Observational studies have found that higher calcium intakes from dairy foods were associated with a higher incidence of prostate cancer. A meta-analysis of the research found that dairy increased prostate cancer risk but not nondairy calcium and supplement sources.

Like most supplements, calcium may interact with prescription medications:

Dolutegravir: The use of calcium with dolutegravir (an HIV medication) can reduce levels of the drug in the blood. Calcium should be taken separately from this medication.Levothyroxine: Calcium carbonate can interfere with the absorption of levothyroxine. Calcium should be taken four hours apart from a dose of levothyroxine.Lithium: Lithium can increase calcium blood levels. Taking calcium supplements could exacerbate this side effect.Quinolone antibiotics: Calcium supplements can reduce the absorption of quinolones (e.g., ciprofloxacin, gemifloxacin, moxifloxacin). It is recommended to take calcium two hours before and after the antibiotic dose.

How Do Different Forms of Calcium Supplements Compare?

Calcium can be supplemented in multivitamin preparations or as a single nutrient. Supplement blends promoted for bone health or for older females can include calcium with several other ingredients.

Several calcium compounds are found in supplements. Calcium carbonate and calcium citrate are the most popular, but one is not necessarily better than the other.

Calcium carbonate tends to cause more side effects like gas, bloating, and constipation, especially in older adults with low levels of stomach acid.

Over-the-counter (OTC) antacids, such as Tums and Rolaids, contain calcium carbonate. If you take these frequently, you may want to include the calcium in your total calcium intake.

Calcium gluconate and calcium lactate provide less elemental calcium. The elemental calcium dose should be listed on the supplement fact label.

When Is the Best Time to Take Calcium?

Absorption of calcium is better when it is taken with food. Calcium carbonate relies on the acidity of stomach acid for absorption. If you take it with food, it is also less likely to cause gas, bloating, and constipation.

What Are Other Ways to Get More Calcium?

Food sources providing the most calcium include dairy products and canned fish. To be sure you are getting calcium in your diet, include the following foods:

Dairy: Yogurt, milk, soy milk, cheese and cottage cheeseFish: Canned salmon or sardines with bonesTofu (made with calcium sulfate)Beans: Soybeans, pinto beansVegetables: Spinach, turnip greens, kale, bok choy, broccoliFruits: Apple, calcium-fortified orange juiceGrains: Breakfast cereals fortified with calcium, whole wheat bread (which has small amounts of calcium)

In the United States, the Food and Drug Administration (FDA) does not regulate dietary supplements the way it regulates prescription medications. As a result, some supplement products may not contain the ingredients listed on the label. 

When choosing a supplement, look for products independently tested or certified by organizations such as NSF, U.S. Pharmacopeia, or ConsumerLab.com. For personalized guidance, consult your healthcare provider, registered dietitian nutritionist (RD or RDN), or pharmacist.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

National Institutes of Health Office of Dietary Supplements. Calcium: fact sheet for health professionals.

Humphrey MB, Russell L, Danila MI, et al. 2022 American College of Rheumatology Guideline for the Prevention and Treatment of Glucocorticoid-Induced Osteoporosis. Arthritis Rheumatol. 2023;75(12):2088-2102. doi:10.1002/art.42646

National Institutes of Health Office of Dietary Supplements. Dietary supplements for weight loss: fact sheet for professionals.

Méndez-Sánchez L, Clark P, Winzenberg TM, et al. Calcium and vitamin D for increasing bone mineral density in premenopausal women. Cochrane Database Syst Rev. 2023;1(1):CD012664. doi:10.1002/14651858.CD012664.pub2

Weaver CM, Alexander DD, Boushey CJ, et al. Calcium plus vitamin D supplementation and risk of fractures: an updated meta-analysis from the National Osteoporosis Foundation [published correction appears in Osteoporos Int. 2016 Aug;27(8):2643-2646. doi: 10.1007/s00198-016-3699-z.]. Osteoporos Int. 2016;27(1):367-376. doi:10.1007/s00198-015-3386-5

Chakhtoura M, Bacha DS, Gharios C, et al. Vitamin D supplementation and fractures in adults: a systematic umbrella review of meta-analyses of controlled trials. J Clin Endocrinol Metab. 2022;107(3):882-898. doi:10.1210/clinem/dgab742

Kahwati LC, Weber RP, Pan H, et al. Vitamin D, calcium, or combined supplementation for the primary prevention of fractures in community-dwelling adults: evidence report and systematic review for the US Preventive Services Task Force. JAMA. 2018;319(15):1600-1612. doi:10.1001/jama.2017.21640

Zhao JG, Zeng XT, Wang J, Liu L. Association between calcium or vitamin D supplementation and fracture incidence in community-dwelling older adults: a systematic review and meta-analysis. JAMA. 2017;318(24):2466-2482. doi:10.1001/jama.2017.19344

Grossman DC, Curry SJ, Owens DK, et al. Vitamin D, calcium, or combined supplementation for the primary prevention of fractures in community-dwelling adults: US Preventive Services Task Force Recommendation Statement. JAMA. 2018;319(15):1592-1599. doi:10.1001/jama.2018.3185

Hofmeyr GJ, Lawrie TA, Atallah ÁN, Torloni MR. Calcium supplementation during pregnancy for preventing hypertensive disorders and related problems. Cochrane Database Syst Rev. 2018;10(10):CD001059. doi:10.1002/14651858.CD001059.pub5

Gomes F, Ashorn P, Askari S, et al. Calcium supplementation for the prevention of hypertensive disorders of pregnancy: current evidence and programmatic considerations. Ann N Y Acad Sci. 2022;1510(1):52-67. doi:10.1111/nyas.14733

Myung SK, Kim HB, Lee YJ, et al. Calcium supplements and risk of cardiovascular disease: a meta-analysis of clinical trials. Nutrients. 2021;13(2):368. doi:10.3390/nu13020368

Yang C, Shi X, Xia H, et al. The evidence and controversy between dietary calcium intake and calcium supplementation and the risk of cardiovascular disease: a systematic review and meta-analysis of cohort studies and randomized controlled trials. J Am Coll Nutr. 2020;39(4):352-370. doi:10.1080/07315724.2019.1649219

Paik JM, Curhan GC, Sun Q, et al. Calcium supplement intake and risk of cardiovascular disease in women. Osteoporos Int. 2014;25(8):2047-2056. doi:10.1007/s00198-014-2732-3

Kopecky SL, Bauer DC, Gulati M, et al. Lack of evidence linking calcium with or without vitamin D supplementation to cardiovascular disease in generally healthy adults: a clinical guideline from the National Osteoporosis Foundation and the American Society for Preventive Cardiology. Ann Intern Med. 2016;165(12):867-868. doi:10.7326/M16-1743

Aune D, Navarro Rosenblatt DA, Chan DS, et al. Dairy products, calcium, and prostate cancer risk: a systematic review and meta-analysis of cohort studies. Am J Clin Nutr. 2015;101(1):87-117. doi:10.3945/ajcn.113.067157

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