Calcium is important for overall health. Almost every cell in our body uses calcium in some way. Some areas where our bodies use calcium is in our nervous system, muscles, heart and bone. Our bones store calcium in addition to providing support for our bodies. As we age, we absorb less and less calcium from our diet, causing our bodies to take more and more calcium from our bones. Over time this aging process can cause or contribute to osteopenia or osteoporosis.
We get calcium from the food we eat. Calcium-rich foods include milk, cheeses and other dairy products. We can also get calcium from vitamins and supplements.
Our bodies like to keep the amount of calcium in our blood within a certain narrow range. This range allows the cells in our body to stay healthy and perform jobs necessary for life. When blood calcium levels are low the amount of calcium in our blood goes below normal, our parathyroid glands release a hormone called parathyroid hormone (PTH). Although this sounds similar to thyroid hormone, PTH is different. PTH tells our bones to release more calcium into the blood stream. PTH also helps activate vitamin D which in turn increases intestinal calcium absorbtion.
We obtain vitamin D from the foods we eat and from our skin in response to sunlight. Because vitamin D promotes absorption of calcium from the intestine,vitamin D helps to build and maintain strong bones. When we have very low vitamin D levels, we can develop an adult form of rickets, called osteomalacia.