Calcium is the most abundant mineral in your body. It is essential for the development and maintenance of strong bones and teeth, where about 99% of the body's calcium is found. Calcium also helps the heart, nerves, muscles, and other body systems work properly. It is probably best known for helping prevent 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. Many factors, including age, disease states, and medications, can affect calcium absorption. Carbohydrates may enhance calcium absorption while coffee and cigarette smoke may impede it.
The best way to get calcium is through food. Many foods are fortified with calcium. But some people may need to take calcium supplements to get the recommended amount. It is especially important for children to get enough calcium in their diets as they are growing and forming bone, and for older people as they start to lose bone.
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 who don't absorb enough calcium, as can happen with Crohn's disease, celiac disease, and some intestinal surgeries.
Getting enough calcium may help prevent or treat the following conditions:
Your body needs calcium to build and maintain healthy bones and strong teeth. People start to lose more bone than their bodies make in their 30s, and the process speeds up as they get older. Studies have shown that calcium, particularly in combination with vitamin D, may help prevent bone loss associated with menopause. It may also help prevent bone loss in older men. If you do not get enough calcium in your diet, your doctor may recommend a supplement.
People with this condition have underactive parathyroid glands. These four small glands 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 doctors. 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 or high blood pressure. Some studies suggest that increasing calcium levels may lower blood pressure slightly. However, not all studies have been positive. 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. Instead, talk to your doctor about the right amount of calcium for you. You may need to take calcium for 6 to 8 weeks before you see any improvement in blood pressure.
Some studies suggest that calcium supplements may play a role in the prevention of high blood pressure during pregnancy and preeclampsia, a combination of high blood pressure, fluid retention, and high levels of protein in the urine that some women develop during the last trimester of pregnancy. However, not all studies show the same benefit. Taking a prenatal vitamin, with magnesium, folic acid, and many other nutrients, and getting enough calcium in food, may lower the risk of developing high blood pressure during pregnancy.
Obesity and Weight Loss
Animal and human studies have found that eating low-fat dairy products may help you lose weight or stay at a healthy weight. However, researchers aren't sure whether the calcium in the dairy products affects weight, or whether it's some other nutrient -- or even a combination of nutrients. In addition, not all studies have been positive. Plus there's no sound evidence that taking calcium supplements, as opposed to eating low-fat dairy products, would help with weight loss. More research is needed.
Preliminary studies in animals and people suggest that calcium supplements, in the range of 1,500 to 2,000 mg per day, may help lower cholesterol slightly. From these studies, it seems that calcium supplements, along with exercise and a healthy diet, may be better at keeping cholesterol at normal levels than at lowering already high cholesterol. More research is needed.
Rickets causes softening and weakening of the bone in children. Although very rare in North America and Western Europe, where children drink a lot of milk, it still happens in many parts of the world. Researchers thought rickets was caused by a vitamin D deficiency. But studies suggest that taking calcium supplements is an effective treatment.
Stroke. In a population-based study, in which large groups of people were followed over time, women who took in more calcium, both through food and 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 have higher amounts of calcium, vitamin D, and milk in their diets are less likely to develop colorectal cancer than those who have low amounts. Researchers are not sure whether calcium supplements would have the same effect, or even whether calcium itself is making the difference.
The richest food sources of calcium include:
- Cheeses, such as Parmesan, Romano, gruyere, cheddar, American, mozzarella, and feta
- Low-fat dairy products, such as milk and yogurt
- Blackstrap molasses
Other good sources of calcium include:
- Brewer's yeast
- Bok choy
- Brazil nuts
- Dried figs
- Dark leafy greens (such as dandelion, turnip, collard, mustard, kale, and Swiss chard)
- 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.