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Calcium is the mineral that builds up our bones and strengthens them. Calcium accounts for 1.5 to 2% of an adult's total body weight. Ninety-nine percent of the calcium in our bodies is stored in the bones and teeth. The remaining 1% is in our blood and soft tissues and is essential for life and health. Without this 1% of calcium, our muscles wouldn’t contract correctly, blood wouldn’t clot, and our nerves wouldn’t transmit messages.

Calcium is the most plentiful mineral in the body. The body does not make its own calcium, which means that we need to get it from our daily diet. A diet rich in calcium is important, especially when bones are growing and developing. After bones are developed, we still need calcium throughout our life to maintain strong and healthy bones. A calcium-rich diet adds to the density of bone tissue. A diet poor in calcium is one factor that can make bones weak and fragile.

Aside from strengthening bones, calcium is necessary for many body functions. Almost every cell in our bodies--including those in our heart, nerves, and muscles--needs calcium. In order for our body to perform properly, the level of calcium in the blood must stay relatively constant. We need to consume enough calcium throughout the day, or our blood will steal calcium from our bones to meet the level it requires. If our diet is low in calcium, our blood takes the calcium it needs from them. When our diet is rich in calcium, our body stores it in the bones. If our bodies continue to steal calcium from the bones, they can become weak and be susceptible to breaking.

How calcium helps our body

Bones: necessary to build, develop, and maintain healthy bones
Heart: maintains normal heartbeat and regulates blood pressure
Blood: important for normal blood clotting, essential for healing
Colon: may offer protection from colon cancer
Nerves: for proper functioning of the nervous system
Muscles: needed for muscle contraction and relaxation

Milk products are the most convenient way to meet our calcium needs. It is essential to take supplements to meet daily calcium needs without milk products. Milk is also a good source of phosphorus and magnesium, which helps the body absorb and use the calcium. Vitamin D is also necessary for utilization of calcium; that is why milk is fortified with Vitamin D.

Green leafy vegetables such as broccoli, collards, kale, mustard greens, turnip greens, and bok choy are good sources of calcium. Shellfish, almonds, Brazil nuts, and dried beans are also sources of calcium, but we need to eat an awful lot of them to meet our daily calcium requirements. Calcium requires enough Vitamin D for the body to use it.

The recommended daily allowances (RDAs) for calcium are:

Babies (up to 6 months): 400 milligrams
Infants (6 months to 1 year): 600 milligrams
Toddlers (1 to 5 years): 800 milligrams
School age (6 to 10 years): 800 to 1,200 milligrams
Adolescents (11 to 24 years): 1,200 to 1,500 mgs.
Non-pregnant women (25 to 50 years): 1,000 mgs.
Pregnant or lactating women: 1,200 milligrams
Postmenopausal women taking estrogen supplements: 1,000 mgs
Postmenopausal women NOT taking estrogen: 1,500 milligrams
Men (25 to 65 years): 1,000 milligrams
Men and women (over 65 years): 1,500 milligrams

Do not take any calcium supplements without the approval of your doctor.
These approximate quantities can serve as a guide to calcium intake:

8-ounce glass of milk = 300 milligrams
2 ounces of Swiss cheese = 530 milligrams
6 ounces of yogurt = 300 milligrams
2 ounces of sardines with bones = 240 milligrams
6 ounces of cooked turnip greens = 220 milligrams
3 ounces of almonds = 210 milligrams

Increased calcium intake for short periods does not usually have toxic effects. The excess calcium is eliminated through the urine feces. An increased risk of kidney stones in persons susceptible to them is sometimes associated with chronically high calcium intake. A diet poor in calcium for long periods of time can lead to calcium deficiency. This leads to osteoporosis, loss of the jawbone and other oral health problems, and hypertension.