University of Illinois Extension

Why Do We Get Osteoporosis?

Bone is a living tissue, not a hard lifeless structure. While we cannot feel it, the bones in our bodies are constantly changing by being built, torn down and rebuilt. During childhood and adolescence, the amount of bone being built is greater than the amount we are losing. In other words, our bodies are producing bone to strengthen the skeletal structure until peak bone mass is reached.

At about age 20-25, the process slows and reverses. More bone is being lost through absorption than is being built. The goal is to keep skeletal bone mass at a maximum amount. We can do this through consuming foods containing calcium and through weight-bearing physical activity. We want to minimize the amount of bone we are losing.

About 98% of the calcium in our bodies can be found in our skeleton. The remainder of the calcium in our bodies is used to contract and relax our muscles, including our heart, clotting the blood, nerve impulses, and stimulation of hormone secretion.

If we do not consume enough calcium to meet our body's needs, it will use the calcium from the bone to keep the body working. When consumption of calcium falls short for long periods of time, the bones become "honeycombed" or weakened, a condition called osteoporosis.

Bones are porous - that means they have air spaces in them. If you have ever seen a cross-section of a bone from an animal, you know that the bone is not solid - it looks like a type of sponge. Human bone is similar. When the bones become weak from the body using the calcium from them to keep our bodies working, the pores become larger and the bones break more easily.