Calcium is an essential mineral that is important in variety of bodily functions including regulating the heartbeat, conducting nerve impulses, clotting blood, hormone secretion, and the building and maintenance of health bones.
Calcium cannot be manufactured by the body, so it is important to get enough of this important mineral through a proper nutrition and dietary supplements. Even after adolescence, adequate calcium intake is important because your body will lose calcium through normal usage in skin, nails, hair, sweat, and other bodily fluids. If you don’t get enough calcium, your body takes calcium out of your bones so as to ensure essential bodily functions are not impaired. This makes your bones weaker.
Recommended Calcium Dosage (RDA)
Normal daily recommended intakes in milligrams (mg) for calcium:
U.S. RDA (mg)
Canada RNI (mg)
Infants and children
Birth to 3 years of age
4 to 6 years of age
7 to 10 years of age
Adolescent and adult males
Adolescent and adult females
The national Osteoporosis Foundation recommends daily calcium intake of 1000-1200 mg/day for adults, and 1500 mg/day for post menopausal women.
Types of Calcium Supplements
Calcium exists in nature only in combination with other substances. This is called a compound. There are many different calcium compounds available. When considering your options, be sure to look at the elemental calcium content supplement and not just the total pill size. The elemental calcium content is the actual amount of pure calcium in the pill.
Calcium carbonate – This is the most common and inexpensive form of calcium supplement. It requires additional acid for optimum absorption, thus it must be taken after meals.
Calcium citrate –Technically speaking, calcium citrate is the calcium salt of citric acid. Because calcium is best absorbed in an acidic environment, calcium citrate is generally considered the most absorbable form of calcium. Calcium citrate can be taken at any time of the day, irrespective of meals. One downside however is that calcium citrate supplements generally have less elemental calcium content, thus more pills need to be taken. Additionally, because of the added acidity, people with acid reflux may not be able to tolerate it.
Coral Calcium – this is a form of calcium derived from coral reefs off the coast of Okinawa, Japan. Coral calcium is similar to calcium citrate (coral reefs are just limestone which is what calcium citrate is derived from), but have an added twist. Coral calcium contains a blend of 70+ trace minerals that may potentially augment the elemental calcium. In addition, there are many reported beneficial health effects above and beyond addressing osteoporosis, but these have yet to be confirmed in western science.
Calcium Aspartate Anhydrous – This is the latest form for calcium compound on the market. Calcium aspartate anhydrous is an organic calcium compound based on L-aspartic acid. This form of calcium’s claim to fame is research showing that it has an absorption rate of 92% (far higher than other compounds).
Calcium Buying Tips
The National Institute of Health recommends you consider the following factors when choosing a calcium supplement:
Purity: Choose calcium supplements with familiar brand names. Look for labels that state “purified” or have the USP (United States Pharmacopeia) symbol. Avoid calcium from unrefined oyster shell, bone meal, or dolomite without the USP symbol, because it may contain high levels of lead or other toxic metals.
Absorbability: Most brand-name calcium products are absorbed easily in the body. If you are not sure about your product, you can find out how well it dissolves by placing it in a small amount of warm water for 30 minutes and stirring it occasionally. If it hasn’t dissolved within this time, it probably will not dissolve in your stomach. Chewable and liquid calcium supplements dissolve well because they are broken down before they enter the stomach.
Calcium, whether from food or supplements, is absorbed best by the body when it is taken several times a day in amounts of 500 mg or less, but taking it all at once is better than not taking it at all. Calcium carbonate is absorbed best when taken with food. Calcium citrate can be taken anytime.
Tolerance: For certain people, some calcium supplements may cause side effects such as gas or constipation. If simple measures (such as increasing your intake of fluids and high-fiber foods) do not solve the problem, you should try another form of calcium. Also, it is important to increase the dose of your supplement gradually: take just 500 mg a day for a week, then slowly add more calcium. Do not take more than the recommended amount of calcium without your doctor’s approval.
Calcium Interactions: It is important to talk with a doctor or pharmacist about possible interactions between your over-the-counter and prescription medications, and calcium supplements. For example, calcium supplements may reduce the absorption of the antibiotic tetracycline. Calcium also interferes with iron absorption. So you should not take a calcium supplement at the same time as an iron supplement – unless the calcium supplement is calcium citrate, or unless the iron supplement is taken with vitamin C. Any medication that you need to take on an empty stomach should not be taken with calcium supplements