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| 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.
For example, if you know you need 1,000 mg of calcium daily but don’t eat much dairy and find that you probably only get 500 mg of calcium from foods, then supplementing another 500 mg daily would be recommended (or you could divide the dose into 250 mg twice daily).
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.
Benefits of Calcium Supplements
Prevents Calcium Deficiency
Some people cannot get enough calcium through their diet and may be at risk of calcium deficiency. This may include people who avoid dairy products for various reasons or individuals who have problems with calcium absorption.
These individuals can take calcium supplements to be sure they are getting enough and prevent developing a deficiency. A calcium deficiency can lead to reduced bone strength and osteoporosis.
Maintains Bone Health
Calcium supplements likely have a role in maintaining bone health, particularly in groups who can’t get enough calcium from food and those who are already at a higher risk of fracture (e.g., an osteoporosis diagnosis).
It is also worth noting that adequate calcium intake is crucial for proper bone development in younger people and for health in older people.
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 more recent systematic review published in the Cochrane Database does not support the use of supplemental calcium and vitamin D for improving BMD in healthy postmenopausal women.
- Fracture risk: Results of research on fracture risk are also mixed. One meta-analysis found that supplemental calcium and vitamins reduced fracture risk by 15% and hip fracture by 30%. A second found that calcium and vitamin D reduced the risk of fractures. However, not all research supports that supplemental calcium and vitamin D helps to prevent fractures in older adults. Two other systematic reviews found that calcium and vitamin D did not affect fractures.
According to the U.S. Preventive Services Task Force, the current body of evidence is not sufficient enough 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.
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.
Unproven Uses
Calcium supplementation may be marketed for several other conditions, but the research is not adequate to support routine supplementation for:
- Metabolic syndrome
- Weight loss
- Cancer prevention
- Heart disease prevention
Risks and Safety Precautions
Taking calcium supplements may have some unintended effects and increase the risk of:
- Heart disease: There are mixed results in research on calcium supplementation and heart disease. One study found that supplemental calcium increased the risk of heart disease by 15% in postmenopausal women. Another found that supplemental calcium increased the risk of heart attack. Others have found calcium supplements do not affect risk. These results led the National Osteoporosis Foundation and the American Society for Preventive Cardiology to review all of the available research in 2016, and at that time, they 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: There are mixed results in the research here as well. Observational studies have found that higher calcium intakes were associated with a higher incidence of prostate cancer. This observed correlation only appears true if calcium intake comes from dairy foods. 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.
Different Forms of Calcium Supplements
Calcium can be supplemented in multivitamin preparations or as a single nutrient. There are also supplement blends that may be promoted for bone health or for older females that include calcium with several other ingredients.
Calcium is also available as several different compounds in supplements:
Calcium carbonate and calcium citrate are the most popular forms. Calcium gluconate and calcium lactate are also available compounds but provide less elemental calcium.
When it comes to calcium carbonate versus calcium citrate, neither form is 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.
For any supplement, reading the supplement fact label is critical to ensuring all the ingredients and doses are appropriate for you. For calcium, the elemental calcium dose should be listed. For example, only 40% of calcium carbonate is elemental calcium. Manufacturers including the amount of elemental calcium eliminates the need for you to calculate the calcium dose.
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.
The Best Time to Take Calcium
The best time to take calcium supplements may differ and should be based on individualized needs. However, it is generally recommended to take calcium supplements with food. Absorption of calcium is better when it is taken with food.
This is especially true if you are taking calcium carbonate and you have low amounts of stomach acid. Calcium carbonate relies on the acidity of stomach acid for absorption. If you take it with food, it is less likely to cause gas, bloating, and constipation.
Calcium citrate does not do this and can be taken without food, but again, calcium absorption is better when taken with food. Vitamin D also helps with calcium absorption, and calcium supplements often contain vitamin D for this reason.
Other Ways to Get More Calcium
Calcium is available in many foods in the diet. 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 cheese
- Fish: Canned salmon or sardines with bones
- Tofu (made with calcium sulfate)
- Beans: Soybeans, pinto beans
- Vegetables: Spinach, turnip greens, kale, bok choy, broccoli
- Fruits: Apple, calcium-fortified orange juice
- Grains: Breakfast cereals fortified with calcium, whole wheat bread (which has small amounts of calcium)
Calcium is also present in some OTC medications, such as antacids. If you take antacids routinely, you can include this in your total calcium intake. However, antacids are not recommended as a way to supplement calcium.
Summary
Calcium is a mineral found in the body. It is also available in the diet and as a supplement. Supplementation is beneficial for people who don’t get enough calcium in their diet. If you feel you are not getting enough calcium, talk with a registered dietitian or your healthcare provider to select a supplement and dosage that works best for you.
