About 99 percent of the body's calcium supply is stored in bone and teeth. When we don't consume enough calcium, the body takes what it needs from our bones in order to maintain an appropriate level in the blood and the rest of the body. This can make our bones weaker. When we provide the body with enough calcium, the body can use it to rebuild old, weak bones, making our bones stronger.

The Recommended Dietary Allowance (RDA) is the average daily intake considered sufficient to meet the nutrient requirements of most healthy individuals. The RDA for calcium can vary with age and gender -- adolescents and older adults generally need more. Your healthcare provider can tell you how much calcium you should be consuming each day.

Food is the best source of calcium. Dairy products, such as milk, yogurt, and cheese, are calcium-rich. Nondairy calcium foods include certain green, leafy vegetables (broccoli, kale, and bok choy), sardines, and salmon (with the bones). In addition, you can find calcium added to some foods, such as calcium-fortified juice, cereal, or soy milk.

Many people find it difficult to get enough daily calcium through diet alone. Supplements can help. Keep in mind that calcium dosing recommendations are given in terms of elemental calcium, but calcium supplements come in different forms (calcium citrate, carbonate, gluconate, etc.). These different forms contain different amounts of elemental calcium. Fortunately, the amount of elemental calcium is listed on most supplements. Just be sure to read the label carefully.

Getting enough calcium through your daily diet and supplements is a great start, but your body needs to absorb the calcium you consume for it to be useful. Calcium (in both food and supplements) is best absorbed in small amounts -- about 500 to 600 mg at a time. So, don't take all your calcium at once. Instead, break it up into small doses several times a day.

Your body needs vitamin D to absorb calcium. While your skin makes vitamin D from the sun, it's usually not enough -- especially in certain areas of the country or during the winter months, when the sun is nowhere to be found. Many people need to get their vitamin D from food (such as fatty fish and fortified milk) or supplements. The recommended daily vitamin D intake varies with age, but most people need 400 to 1000 international units (IU) a day.