Calcium is the most abundant mineral in the body. It is essential for the development and maintenance of strong bones and teeth, the location of about 99% of the body's calcium. Calcium also helps the heart, nerves, muscles, and other body systems work properly. It is probably best known for its effects in preventing osteoporosis. Your body needs several other nutrients in order for calcium to be absorbed and used properly, including magnesium, phosphorous, and especially vitamins D and K.
The best way to get calcium is through food (see Dietary Sources). But although many foods are fortified with calcium, some people may still need to take calcium supplements. In fact, according to the National Institutes of Health, many Americans consume less than half the amount of calcium recommended to build and maintain healthy bones. It is especially important to get enough calcium as you age. Postmenopausal women, people who consume large amounts of caffeine, alcohol, or soda, and those who take corticosteroid medications may need calcium supplements. Calcium deficiency can be found in people with malabsorption problems, such as Crohn's disease, celiac disease, and surgical intestinal resection.
Getting enough calcium can help prevent or treat the following conditions:
Osteoporosis
Calcium is necessary to help build and maintain healthy bones and strong teeth. Studies have shown that calcium, particularly in combination with vitamin D, can help prevent bone loss associated with menopause, as well as the bone loss experienced by older men. If you do not get enough calcium in your diet, taking a supplement may be necessary.
Hypoparathyroidism
People with this condition have underactive parathyroid glands, which are four small glands that sit on the four corners of the thyroid in the neck and produce a hormone that regulates calcium, phosphorous, and vitamin D levels in the body. People with this condition should follow a high-calcium, low-phosphorous diet as prescribed by their doctor. Most often, they will also need to take calcium supplements.
Premenstrual Syndrome (PMS)
One large, well-designed study showed that women who took 1,200 mg of calcium per day reduced their symptoms of PMS by 50%, including headache, moodiness, food cravings, and bloating. A smaller study suggested that calcium may help reduce menstrual pain.
High Blood Pressure
People who do not get enough calcium may be at higher risk for hypertension, and there is some mixed evidence that suggests increasing calcium levels may lower blood pressure slightly. However, not all studies have found that benefit; and researchers aren’t sure whether calcium supplements would have any benefit, or whether it’s the effects of a diet that includes low-fat dairy products (which contain calcium) that is responsible. If you want to try calcium supplements, do not stop taking your blood pressure medication; talk to your doctor and let the doctor determine the proper dose of calcium for you. You may need to take calcium for 6 - 8 weeks before you see any improvement in blood pressure.
Some studies suggest that calcium supplementation may play a role in the prevention of pregnancy-induced high blood pressure and preeclampsia (a combination of high blood pressure, fluid retention, and high levels of protein in the urine that some women develop in the last trimester of pregnancy). However, not all studies show the same benefit. A prenatal vitamin, which provides magnesium, folic acid, and many other nutrients, together with adequate calcium intake through the diet, may lower the risk of developing high blood pressure during pregnancy.
Obesity
Some animal and human studies have found that consuming low-fat dairy products may help you lose or maintain a proper weight. However, researchers aren’t sure whether the calcium in the dairy products affects weight, some other nutrient -- or even a combination of nutrients. In addition, not all studies have found any benefit; and there’s no sound evidence that calcium supplements (as opposed to dairy products) would help in losing weight. More research is needed.
High Cholesterol
Preliminary studies in animals and people suggest that calcium supplements, in the range of 1,500 to 2,000 mg per day, may help to lower cholesterol slightly. From these studies, it appears that calcium supplements (along with exercise and proper diet) may be better at keeping cholesterol at normal levels than at lowering them once cholesterol is already high. More research in this area is needed.
Rickets
Rickets causes softening and weakening of the bone in children. Although virtually eliminated in North America and Western Europe, where milk consumption is common, it still occurs in many parts of the world. Researchers have thought that rickets is caused by a lack of vitamin D; however, a study in 2000 showed that calcium supplementation is an effective treatment.
Other Uses
Stroke -- In a population-based study (one in which large groups of people are followed over time), women who take in more calcium, both through their diet and with supplements, were less likely to have a stroke over a 14-year period. More research is needed.
Colon Cancer -- Although not all studies agree, some show that people who consume higher amounts of calcium, vitamin D, and milk in their diets are less likely to develop colorectal cancer than those who consume low amounts of the same nutrients. But researchers are not sure whether calcium supplements would have the same effect as calcium in the diet, or even whether calcium itself is responsible for the benefit.
Dietary Sources:
The richest dietary sources of calcium include cheeses (such as parmesan, Romano, gruyere, cheddar, American, mozzarella, and feta), low-fat dairy products (milk, yogurt), tofu, and blackstrap molasses. Some other good sources of calcium include almonds, brewer's yeast, bok choy, Brazil nuts, broccoli, cabbage, dried figs, kelp, dark leafy greens (dandelion, turnip, collard, mustard, kale, Swiss chard), hazelnuts, oysters, sardines, and canned salmon,.
Foods that are fortified with calcium, such as juices, soy milk, rice milk, tofu and cereals, are also good sources of this mineral.
Available Forms:
There are a number of forms of calcium available as dietary supplements. They differ in the amount of calcium they contain, how well they are absorbed by the body, and how much they cost. The two most popular forms are calcium citrate and calcium carbonate.
- Calcium citrate: Easily absorbed and digested by the body, particularly in the elderly. It does not contain as much elemental calcium (the amount your body actually absorbs) as calcium carbonate. It is more costly than calcium carbonate, however. Also, calcium citrate should not be used with aluminum-containing antacids (see Possible Interactions).
- Calcium carbonate: Less expensive than calcium citrate and contains more elemental calcium. Requires a certain amount of stomach acid to be absorbed, so it is usually taken with a glass of orange juice. Many antacids contain calcium carbonate.
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