Calcium

What it is

Calcium is the most abundant mineral in the body. Almost all calcium in the body is stored in bones and teeth, giving them structure and hardness.

Sources: NIH Office of Dietary Supplements: Calcium - Health Professional Fact Sheet ↗ · NIH Office of Dietary Supplements: Calcium - Consumer ↗

How it's thought to work

• Your body needs calcium for muscles to move and for nerves to carry messages.
• Vitamin D helps your body absorb calcium.
• Calcium can attach to fats and reduce the amount of fat that your body absorbs.

Source: NIH Office of Dietary Supplements: Calcium - Consumer ↗

What the research has found so far

• Some studies found calcium supplements raise bone density in older adults, but others did not.
• A review of 8 trials in adults over 50 found calcium plus vitamin D lowered total fractures by 15% and hip fractures by 30%.
• Another review found calcium alone had no effect on hip fracture risk.
• Some research shows high calcium intake from food and supplements goes with lower colon and rectal cancer risk, but other studies do not.
• Some studies show men with high calcium intake from dairy foods have more prostate cancer.
• Calcium supplements might lower the risk of preeclampsia in some pregnant women who consume too little calcium.
• Research has not clearly shown whether calcium helps with weight loss or prevents weight gain.

Sources: NIH Office of Dietary Supplements: Calcium - Consumer ↗ · NIH Office of Dietary Supplements: Calcium - Health Professional Fact Sheet ↗

On Calcium and aging, PubMed lists 377 trials in people, 504 studies that watched people over time, 7 animal and lab studies. See the counts and searches

Side effects and risks

• Calcium supplements might cause gas, bloating, and constipation in some people.
• Calcium carbonate appears to cause more of these effects than calcium citrate, especially in older adults with low stomach acid.
• High calcium in blood and urine can cause poor muscle tone, poor kidney function, nausea, weight loss, and abnormal heart rhythms.

Sources: NIH Office of Dietary Supplements: Calcium - Consumer ↗ · NIH Office of Dietary Supplements: Calcium - Health Professional Fact Sheet ↗

Who should be careful, and drug interactions

• Taking calcium supplements with dolutegravir, an HIV medicine, can lower blood levels of the medicine.
• Levothyroxine is not absorbed well within 4 hours of a calcium carbonate supplement.
• Long-term lithium use, or lithium taken with calcium supplements, can lead to abnormally high blood calcium.
• Quinolone antibiotics are not absorbed well within 2 hours of a calcium supplement.

Source: NIH Office of Dietary Supplements: Calcium - Consumer ↗

Approval and legal status

FDA has approved a health claim for supplements with calcium and vitamin D to reduce the risk of osteoporosis.

Source: NIH Office of Dietary Supplements: Calcium - Health Professional Fact Sheet ↗

Amounts used in studies

What studies or labels describe, not a recommendation.

• Recommended daily calcium for adults ranges from 1,000 to 1,200 mg, depending on age and sex.
• Calcium or calcium plus vitamin D supplements commonly contain 500 or 600 mg.
• The upper daily limit for adults 51 and older, from all sources, is 2,000 mg.
• The body absorbs calcium best at doses of 500 mg or less at one time.

Sources: NIH Office of Dietary Supplements: Calcium - Health Professional Fact Sheet ↗ · NIH Office of Dietary Supplements: Calcium - Consumer ↗

Roughly what it costs

The 5 products we list that contain Calcium cost from $8.59 to $19.99, as read from the makers' pages. See the products

Questions to ask your doctor

• Is Calcium a sensible option for me, given my health and the medicines I take?
• Could Calcium interact with any medicine or supplement I already take?
• What side effects should I watch for, and when should I stop or call you?
• Supplements aren't checked by the FDA before sale. Is there a brand or a third-party test seal you would trust?
• How would we tell whether it is helping, and when should we review it?