Most people, when they think about bones, think they are just an inert framework to hold their flesh and innards upright. Not true. Bone is an active organ, made up of tissue and cells in a continual state of activity throughout a lifetime. Bone has two layers: a composed mixture of inert minerals around a protein core which together contribute to the strength and flexibility of the skeleton.
Sixty-five percent of bone tissue is inorganic mineral (mostly is calcium and phosphorous) which provides the hardness of bone. The remaining 35% of bone tissue is an organic protein matrix. Of the matrix 90-95% is type I collagen, a fibrous protein. The collagen fibers twist around each other in a triple helix and become the scaffold upon which minerals are deposited.
(Take a look at the "Strong Bones for Life" video at the bottom of the page for some suggestions on staying healthy.)
There are three stages in bone development: growth, modeling and remodeling. The growth stage lasts until about age 20 when the length of bone growth ends. In the modeling stage, bones can change shape and become thicker and more durable. Archeological investigations can sometimes show the diet of ancient man along with the stress of hard physical labor, determined through the bones left behind. Remodeling, the replacement of old bone tissue with new tissue, goes on throughout adulthood, but after about age 34, the balance between bone breakdown and reformation begins to end, leading to an inevitable loss of bone mineral density (BMD) with age.
Although BMD is associated with risk of bone fracture, it isn't the sole determinant of fracture risk. Bone quality (shape and strength) and propensity to fall (lack of balance or mobility) also factor into risk assessment. A malnourished, highly active person is susceptible to bone fracture if the mineral content of the bones is too low.
Calcium levels in the blood must be maintained within a very narrow concentration range for normal bodily functions - muscle contraction and nerve impulse conduction. These functions are so vital to survival that the body will leach minerals out of bone to maintain normal blood calcium levels. Inadequate calcium intake is a living example of robbing Peter to pay Paul.
Many Americans, especially the elderly, are at high risk for deficiencies of several micronutrients. Some of these nutrients are critical for bone health, and the Linus Pauling Institute (LPI) recommends supplemental calcium, vitamin D, and magnesium for healthy adults.
Some lifestyle factors can influence BMD. Smoking can be actually harmful to bones; however quitting may reverse some of the harm accrued. Physical activity and exercise has great influence across all stages of bone development.
c. 2012 - Live2AgeWell.com
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The following video might help you understand what you can do to improve your health as you age: