As the most plentiful mineral in the body, calcium plays a key role in the development and maintenance of bones and teeth. Calcium enables the contraction of muscles, including the function of the body's most important muscle, the heart. It is also essential for normal blood clotting, proper nerve impulse transmission, and the appropriate support of connective tissue.

Almost every segment of the population—women, children, teenagers, men, unborn babies, and the elderly—benefit from calcium in their daily diet. The mineral is an important dietary supplement for those who are undergoing significant periods of bone growth, such as in childhood, during pregnancy, and while breast-feeding.

Calcium is an effective weapon for the aging population as they combat osteoporosis. A condition that simply means "porous bones," osteoporosis attacks bones when they are their most vulnerable. As the body ages, bones lose more calcium, and it becomes vital to supplement the diet with calcium in order to encourage bone growth and prevent or slow down the process of osteoporosis.

General use

While the body relies on the presence of calcium for many of its everyday functions, the number of reasons why the mineral should be supplemented in the diet are numerous. Calcium is beneficial to everyone, but re-search has shown that women may benefit more than others. A study in the October 1999 issue of the journal Obstetrics & Gynecology found that pregnant women who do not get enough calcium in their diet can increase the bone mineral content of their fetus by about 15% by taking 1,300 mg of a calcium supplement per day during their second and third trimesters. For those women who already consume enough calcium, the additional supplements do not have this effect. Additional research shows that calcium deficiencies lead to preeclampsia during pregnancy, causing high blood pressure, swelling, and weight gain greater than 1 lb (0.5 kg) per day. The risk of preeclampsia developing lowers by 45–75% for women who receive calcium supplementation.

Premenstrual syndrome (PMS) is another condition women face that may be alleviated by the use of calcium supplements. Researchers at the National Institute of Mental Health (NIMH) concluded that those women who took 1,200 mg of calcium per day reduced their overall PMS symptoms by more than 50%. In the study, calcium supple-mentation led to the reduction of psychological PMS symptoms (such as mood swings) by 45%, food cravings by 54%, and bloating and water retention by 36%.

A 1999 study reported that researchers have found that increasing the amount of daily calcium consumed by women may reduce their risk of stroke. Those women in the Nurses' Health Study who took more than 400 mg of calcium daily were at the lowest risk for a stroke, while those who consumed more than 600 mg each day did not have an increased benefit. Researchers believe that the risk of stroke is reduced by calcium from decreased cholesterol levels, or by stopping the formation of blood clots that cause strokes.

For elderly postmenopausal women, the prevention of osteoporosis becomes critical. In order to maintain bone mass during this time, a study conducted in 1999 concluded that a low-dose hormone replacement therapy (HRT) combined with calcium and vitamin D supple-mentation is an effective therapeutic option for prevention of osteoporosis. Estriol, which is used in HRT, appears to be helpful in controlling menopausal symptoms. Results from research regarding this use of estriol on bone density have been contradictory, according to the Alternative Medicine Review, with the results showing the most effectiveness coming from Japanese studies.

Calcium alone is frequently prescribed with estrogen at the beginning of menopause to treat or prevent osteoporosis. This therapy is recommended to guard against the increased loss of calcium in the bones due to increasing age. As bones lose more calcium they become dense and brittle, and more vulnerable to the attack of osteoporosis. This condition is most common in people over 70, and in women after menopause, where it may increase the risk of broken hips, ribs, and pelvis, and the weakening of other bones. Increased physical exercise is also important for bone strengthening.

On the other hand, although calcium supplementation is useful in lowering the risk of osteoporosis in Western women, more research is needed to determine why the rates of osteoporosis are low in some Eastern societies with low-calcium diets. There is evidence that osteoporosis, like coronary artery disease, is primarily a problem in Western societies. In addition, accumulating evidence that a diet high in fruits and vegetables helps to prevent fractures suggests that the level of calcium in the diet is not the only nutritional factor involved in osteoporosis.

Calcium has been shown to be beneficial to the colon. Among those people taking calcium supplements, research points to a modest reduction in the recurrence of polyps in their colons. Colon polyps are benign tumors that often turn cancerous. Researchers think that calcium binds to carcinogens, preventing abnormal cell growth.

Stemming from its active role in building bone density throughout the body, calcium may prove particularly beneficial for strengthening of the jawbone. Dental researchers at the State University of New York at Buffalo report that calcium supplementation may prevent periodontal disease as it builds a strong jawbone. Periodontal, or gum, disease is an infection caused by bacteria that deposits in pockets between the teeth and gums, and is the leading cause of tooth loss in the United States. As the infection progresses, the jawbone that holds a tooth in place is eventually destroyed, causing the tooth to loosen and fall out. The researchers contend that calcium's overall bone-building role would equal a stronger jawbone that would better fight off gum disease.

While supplements of calcium can be found in many forms, research has shown a promising benefit if it is obtained from dairy foods, rather than supplements or leafy greens—calcium in the form of dairy may actually prevent weight gain. Those in the study who consumed at least 1,000 mg of calcium a day (equaling about 3 cups, or 750 ml of skim milk), gained 6–7 lb (2.7–3.2 kg) less over two years than those with low-calcium diets. Researchers of Purdue University speculate that calcium probably prevents weight gain by increasing the breakdown of body fat and decreasing its formation. It is important to note, however, that dairy products should be consumed in moderation, as other research conducted has indicated that dairy products are not necessarily a good source of absorbable calcium. In addition, other studies indicate that women are often reluctant to increase their intake of dairy products because they dislike milk, suffer from lactose intolerance, or fear that they will gain too much weight.

Calcium is proving essential to those children around the world who are stricken by rickets. Rickets is a deficiency condition in children that affects developing cartilage and newly formed bone throughout the body, causing severe deformities. Often thought to be a result of the inadequate intake of vitamin D from dietary sources or lack of exposure to sunlight, research reported in 2000 has found that children with rickets respond well to calcium supplementation. While rickets is still rare in most developed countries, it is becoming more common in the United States due to lower milk consumption by children; and it remains a problem in many other parts of the world. Researchers conclude that effective treatment for the condition is calcium supplementation alone, or in combination with vitamin D. Osteomalacia, or the adult form of rickets, also responds to calcium supplementation.

Evidence is accumulating in the United States that women are not the only group at risk for insufficient dietary levels of calcium. Children and adolescents are also at risk, according to a 2001 report from the National Institutes of Health. Researchers found that "only 13.5% of girls and 36.3% of boys ages 12 to 19 in the United States get the recommended daily amount (RDA) of calcium, placing them at serious risk for osteoporosis and other bone diseases" in their adult years. The report listed increased consumption of soft drinks and decreased consumption of milk as contributing to the problem.


Calcium may be supplemented in the diet in a variety of ways. Numerous foods are rich in calcium, including dairy products (such as milk, yogurt, and cheese) and leafy green vegetables like turnip greens, broccoli, kale, and collards. Canned salmon, sardines, shrimp, and tofu are also high in calcium. More foods are being fortified with calcium, making it easier to ensure the proper amount of the mineral is consumed. Calcium-fortified foods range from cranberry juice cocktail, cereal and waffles, to orange juice and flour. With almost every segment of the population consuming too little calcium, researchers recommend calcium-fortified foods to increase daily calcium intake.

While the types of food calcium may be obtained from continues to increase, most people still lack enough of the essential mineral. For those who are not getting enough calcium from foods, supplements are an acceptable alternative. The chemical form of calcium supplements come in five varieties: carbonate, citrate, lactate, phosphate, chelate, and citrate malate. The supplements are available as tablets, syrup, or suspension form. Calcium supplements should be stored at room temperature and away from moisture and sunlight. It should not be stored in the bathroom, and the liquid forms should not be frozen.

Experts state that calcium is best absorbed from the citrate malate form, or the type of calcium found in some juices, but they recommend calcium carbonate for the overall amount of calcium it offers and its affordability. Calcium carbonate can be found in antacids, and it is absorbed better when taken with meals. Food slows down the time it takes substances to travel through the gut, giving the calcium more time to be absorbed. Absorption is key for the proper functioning of calcium. Sufficient levels of vitamin D and hydrochloric acid in the stomach, and the presence of other minerals, such as magnesium and phosphorous are essential for quick absorption.

The body may also be better able to absorb calcium when taken along with ingredients extracted from chicory root. Research indicates that Raftilin inulin and Raftilose oligofructose, both extracts from chicory root, are dietary fibers that are not digested in the stomach or the small intestine. Instead, they are fermented by Bifidobacteria in the colon—beneficially leading to increased calcium absorption throughout the body, with emphasis on bone tissue. Additionally, Oligofructose improves the texture and mouthfeel while improving taste and fruit flavors in low-fat yogurts. Inulin is used for fat replacement and fiber enrichment of reduced-fat and fat-free sour cream and whipped topping.

There are many ways to ensure calcium is part of a daily diet, but it is important that the recommended daily allowance (RDA), or appropriate dosage of the mineral be followed. The RDA of calcium for adults is 800 mg; pregnant women and young adults should be certain their intake equals 1,200 mg per day. Adults over 50 should increase their intake to 1,000 mg per day with supplements that include vitamin D.

Calcium supplements may be taken with a large glass of water during or after a meal. Tablets in chewable form must be chewed thoroughly before swallowing, and effervescent tablets should be diluted in cold water or juice before taking. It is recommended that other medications be taken two hours after any calcium supplement. The simultaneous intake of calcium may interfere with the absorption of other drugs. Do not take more than 500 mg of calcium at one time for the best absorption of the mineral.


When adding calcium supplements to the diet, it is recommended that it not be taken within one to two hours of eating bran, or whole grain cereals or breads. Large amounts of alcohol or caffeine containing beverages or tobacco should be avoided. Large amounts of calcium, phosphates, magnesium, or vitamin D in medication or dietary supplements should not be taken unless directed by a physician. Those with diarrhea, stomach trouble, parathyroid disease, sarcoidosis, or kidney stones should consult with their physician before taking calcium.

Side effects

Calcium is typically well tolerated by those who add it to their diets, but if the mineral is taken in high levels it can cause several side effects, including: nausea, vomiting, loss of appetite, constipation, stomach pain, thirst, dry mouth, increased urination, and weakness. While these side effects are rare, it is even more unlikely to experience the life-threatening symptoms of an irregular or very slow heart beat. If these dangerous symptoms appear while taking calcium, use of the mineral should be discontinued and emergency treatment should be sought. An overdose of a calcium supplement may lead to confusion, irregular heartbeat, depression, bone pain, or coma.


It is important that all over-the-counter (OTC) or prescription medications are reviewed with a physician before beginning calcium supplement.

According to the Complete Guide to Prescription & Nonprescription Drugs, the following are some of the drugs that may cause possible interactions if taken with calcium:

  • alendronate
  • anticoagulants
  • calcitonin
  • calcium-containing medicines
  • chlorpromazine
  • oral contraceptives
  • corticosteroids
  • digitalis preparations
  • diuretics, thiazide
  • estrogens
  • etidronate
  • iron supplements
  • meperidine
  • mexiletine
  • nalidixic acid
  • nicardipine
  • nimodipine
  • oxyphenbutazone
  • para-aminosalicyclic acid (PAS)
  • penicillins
  • pentobarbital
  • phenylbutazone
  • phenytoin
  • pseudoephedrine
  • quinidine
  • salicylates



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Food and Drug Administration, Office of Consumer Affairs, HFE–88, Rockville, MD 20857.

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