Bone consists of calcium and phosphorous crystals embedded in a framework of interlocking protein fibers. The protein fibers are made primarily of collagen. The mineral crystals give bone hardness, strength, and rigidity. Collagen fibers impart their quality of flexibility. Hydroxyapatite composes 67 percent of the weight of bone, and the collagenous fibers make up the remaining 33 percent.*
The average adult has 1,000 – 1,200 grams of calcium in the body. Bones are the body’s largest calcium storehouse and will release calcium into the bloodstream in order to ensure correct blood levels of calcium. Thus, blood calcium levels can be normal while bone loss can be considerable.
Between 2 – 4 percent of a person’s skeleton is remodeled every year. This means that calcium and other minerals leave the bone in a process called resorption and then must be “remodeled” or replaced. Whether due to poor nutrition or reduced hormone levels with the onset of aging, the loss of calcium and other minerals from the bone creates tiny holes that make bones weak and brittle, particularly if collagen is being lost.
It has been estimated that post-menopausal women lose 0.7 percent to 2 percent of their bone per year while men lose 0.5 percent – 0.7 percent. Between 45 and 75 years of age, women lose 30 percent of their skeletal structure and men lose 15 percent.
Who Needs to Supplement Calcium?
Research has indicated that 85 percent of women over the age of 20 and at least 50 percent of men from age 35 consume less than the RDI for calcium. Caffeine, alcohol, sugar, high protein diets and soda (particularly sodas that are high in phosphorous) can deplete calcium.
In addition, calcium absorption has long been thought to be stomach-acid dependent, but both stomach acid production and calcium absorption decline with age.