Those advertisements pushing milk as the answer to strong bones are almost inescapable. But does "got milk" really translate into "got strong bones?"

The pro-milk faction believes that increased calcium intake - particularly in the form of the currently recommended three glasses of milk per day - will help prevent osteoporosis, the weakening of bones. Each year, osteoporosis leads to more than 1.5 million fractures, including 300,000 broken hips.

On the other side are those who believe that consuming a lot of milk and other dairy products will have little effect on the rate of fractures but may contribute to problems such as heart disease or prostate cancer.

Which view is right? The final answers aren't in. But here is a summary of what's currently known about calcium and its effects on the body.

Calcium is a mineral that the body needs for numerous functions, including building and maintaining bones and teeth, blood clotting, the transmission of nerve impulses, and the regulation of the heart's rhythm. Ninety-nine percent of the calcium in the human body is stored in the bones and teeth. The remaining 1 percent is found in the blood and other tissues.

The body gets the calcium it needs in two ways. One is by eating foods that contain calcium. good sources include dairy products, which have the highest concentration per serving of highly absorbable calcium, and dark leafy greens or dried beans, which have varying amounts of absorbable calcium.

The other way the body gets calcium is by pulling it from bones. This happens when blood levels of calcium drop too low, usually when it's been a while since having eaten a meal containing calcium. Ideally, the calcium that is "borrowed" from the bones will be replaced at a later point. But, this doesn't always happen. Most important, this payback can't be accomplished simply by eating more calcium.

Bone is living tissue that is always in flux. Throughout the lifespan, bones are constantly being broken down and built up in a process known as remodeling. Bone cells called osteoblasts build bone, while other bone cells called osteoclasts break down bone.

In healthy individuals who get enough calcium and physical activity, bone production exceeds bone destruction up to about age 30. After that, destruction typically exceeds production.

Learn more at: http://www.hsph.harvard.edu/nutritionsource/calcium.html