In typical western countries, many people have diets too low in calcium. In the United States, over half the people in most age groups don’t consume enough calcium.
US Percent Not Meeting Recommended Calcium Intake
- 6 to 11 years old: ...Males 44% , Females 58%;
- 12 to 19 years:....... Males 64%, Females 87%;
- Over age 19: ...........Males 55%, Females 78%
Information from the US National Institutes of Health (NIH) and an independent reference publication, Pharmacist’s Letter, help the consumer decide what to do.
Calcium and Health
Bone Health
Inadequate calcium intake can weaken bones and increase the risk of fractures—broken bones. Broken bones, such as hip fractures, can be devastating to health in older people, and carry a substantial risk of further complications, including death.
Blood Pressure
Higher levels of calcium intake through vegetables have been associated with less high blood pressure.
Cancer
Studies of the potential benefit of calcium in reducing colon cancer are indeterminate. On the negative side, some studies suggest high calcium intake increases the risk of prostate cancer. Because of this, the current recommendation for men over 19 years old is to consume a “modest amount” of calcium each day, about 1000 to 1200 mg.
Kidney Stones
It used to be thought that high calcium consumption led to kidney stones. However, studies now suggest that calcium consumption actually lowers the risk of stones. Instead, not drinking adequate water and consuming a high amount of foods containing oxalates are bigger risks for most people.
Weight management
Several observational studies have found an association of high calcium intake with better weight control. However, these studies are not “powerful,” since they are not randomized or prospective. A possible mechanism is that calcium might bind to fat molecules in the intestines and decrease fat absorption. Recent studies have not been encouraging.
Recommended Intake (from the US Institute of Medicine, National Academies of Science)
Age, years ------ Mg Calcium each day
- 1-3: ____500
- 4-8: ____800
- 9-18: __1300
- 19-50: _1000
- 51+:___1200
(For infants and pregnancy, the recommendations are different. Other sources, including Canadian professional societies, have slightly different recommendations.)
The Scoop On Dietary Supplements
Many products are available. They differ by the chemical form of calcium, which is always stated on the product label. Pharmacist’s Letter offers a summary.
(Key: chemical name [percent elemental calcium by weight] comments).
Calcium acetate [25%] Often used in kidney failure.
Calcium carbonate [40%] Provides the highest amount of calcium by weight; easily absorbed especially when taken with a meal, but not in a low acid stomach. People taking medications to lower acid such as Prilosec or Zantac may absorb less.
Calcium citrate [21%] Absorbed better than carbonate in people taking medications to reduce stomach acid, or who have other absorption problems; it is better absorbed on an empty stomach than carbonate.
Calcium gluconate [9% ] More soluble than citrate, but less calcium by weight, so multiple doses usually needed to achieve target amount of calcium.
Calcium phosphates [31-38%] Not as soluble as carbonate.
Calcium lactate [13%] Multiple doses needed to achieve target amount of calcium. About as soluble as gluconate.
Calcium glucarate [12%] Multiple doses needed to achieve target amount of calcium; may decrease estrogen level; “...there is not enough evidence to support its use...” (to prevent estrogen-related cancers).
Calcium glubionate [6.5%] Multiple doses needed to achieve target amount of calcium.
Note: Some products may also contain other ingredients such as vitamin D and vitamin K. Vitamin D may be useful to help absorb calcium in people who have inadequate D levels. Similarly, low vitamin K levels may increase the risk of fractures, so supplemental K may be useful in those people. Preliminary research suggests magnesium may help improve bone density.
How Much Is Too Much?
The Tolerable Upper Limit (UL) of calcium is 2500 mg a day.
Learn More About Calcium and Health, including medical conditions that involve calcium.
Sources
NIH paper updated 12/4/2008
Pharmacist's Letter 2008;24(10):241008.
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