These similar-sounding cells each have specific roles:

* Osteoblasts: bone building cells that bring minerals into bone tissue--they help build the structure.
* Osteoclasts: cells that release calcium and help break down unwanted bone tissue.

In an ideal world, replaced bone--that is, bone tissue that is broken down--would equal absorbed bone. However, there are a few big kids on the block that influence this process:

* Hormones and other body chemicals
* Mechanical stress--weight bearing exercise (walking, jogging, toning weight training) or lack of it. Exercise helps build new bone tissue.
* Calcium, vitamin D, and other vitamin and mineral intake

An imbalance in any of these three can set up your skeleton to start losing bone tissue.

In fact, this imbalance is the primary cause of osteoporosis--a continual loss of bone from the matrix that creates our skeletons. Osteoporosis doesn't announce itself boldly. It doesn't usually get a diagnosis until someone suffers from hip, wrist, or spinal fractures.

Why Women Seem More Susceptible to Osteoporosis

* Women typically have smaller bones
* Women have more direct hormonal influences on bone structure (menopause is a big factor here, with diminishing estrogen levels, etc.)

Estrogen promotes healthy, dense bones--in women and men. However, women have a more defined "schedule" concerning estrogen production. Estrogen receptors on bone surfaces, depots in a sense for the hormone, help promote bone maintenance and growth.

During perimenopause, as a woman's estrogen production slows, the number of estrogen receptors also diminishes. Increasingly lower estrogen levels impair the ability of bone cells to adequately build bone, resulting in loss of bone density and strength.

Later, in the five to seven years following menopause, women can lose up to 20 percent of their bone mass--a very real risk for osteoporosis.

If Affects One in Eight Men, Too
Given this number, it's not surprising that one out of every two women over 50 will have an osteoporosis-related fracture in their lifetime. However, so will one in eight men.

Why? Because declining testosterone levels, poor calcium intake, and prostate health issues, including prostate cancer history, can all lead to osteoporosis in men.

Why Calcium is Important
Calcium is the most abundant mineral in your body. You need it for blood clotting (the good kind), nerve impulses, muscle movement, and cell metabolism. Of course, calcium is required for maintaining and building healthy bones and teeth.

Interestingly, in nature, calcium only exists with other compounds and not on its own. To be usable by our bodies, aka "bioavailable," calcium compounds are usually part of fortified foods or supplements. That's why you'll see the calcium listed as "calcium carbonate" or "calcium citrate."

Phosphorous
Phosphorus is an important nutrient. It's essential for bone building. In fact, about 85 percent of the phosphorus in our bodies is found in our bones.

Calcium and Phosphorus: A Dynamic Duo
Research shows us that Calcium and phosphorus play very well together, to the point where the importance of phosphorus intake may have been underestimated.

Calcium phosphate seems to provide the biggest nutritional punch for healthy bones.

Vitamin D
Vitamin D helps the body absorb calcium and phosphorus. Even though vitamin D is a fat-soluble vitamin (which usually hang around in the body a bit longer), it needs to be replenished fairly often. Vitamin D is found in many supplements and fortified foods, and is usually in one of two major types: ergocalciferol and cholecalciferol, or D2 and D3.

Magnesium
Magnesium is an amazing mineral. It helps keep our cholesterol levels in check, keeps our cells energized, helps our nerve cells communicate, and supports our immune system.

Skeletons Won't (and shouldn't) Stand Still
Bones keep growing and changing throughout our lifetime--they just don't stand still. For healthy bones, you shouldn't either. And, if you think you're not getting the calcium, vitamin D and other minerals you need from your diet, consider a complete calcium and mineral supplement as part of your daily regimen. Remember, your skeleton is counting on you!