Posted by kathryn in The Micronutrients

During a previous Q & A Thursday , I answered a question on cow’s milk and touched on the importance of the mineral, calcium, for bone health. Following a comment , I thought I ‘d expand on this. It’s a big topic, so I’m going to cover the subject in a series of posts.

There’s still a lot that isn’t known about calcium, bone health and preventing osteoporosis. While the public health messages are simple, “eat dairy for strong bones”, to date a lot of research on this subject has been contradictory.

Bones

The adult skeleton is made up of 206 bones, which range in size from the tiny ear bones, through to the long femur – the thigh bone.

We have bones for a number of reasons. They provide structure and support to your body, while also protecting your internal organs from damage.

Bones are connected by joints and have muscles attached – this enables you to move around. Some bones also contain bone marrow, which is responsible for forming new blood cells.

The other function of bone, is as a store-house for calcium .

Calcium in the body

About 99 percent of the calcium in your body is in your bones, while about 1 percent is in your bloodstream.

While you may know calcium is important for bone health, it actually has much more vital day-to-day tasks – it’s involved in transmitting nerve impulses, forming blood clots, as well as maintaining skeletal and heart muscle contractions. It’s therefore important for our daily survival.

For all these activities to take place, there must be a constant, regulated level of calcium in the bloodstream . While we do get calcium from our food, in order to maintain this specific blood level, calcium is shifted in and out of our bones. People tend to think of bones as being solid and stable, however, they actually change frequently.

Specialised cells called osteoclasts breakdown and resorb bone matrix into the bloodstream, when more calcium is needed. While, other cells, osteoblasts are responsible for bone formation.

Bone health: the series

This is part one of a three-part series on bone health. The next posts can be found at:

• Bone health II: the calcium debate
• Bone health III: how to ensure you have strong, healthy bones

10 July, 2007