Osteoporosis is the gradual loss of bone that occurs in both women and men as they get older, but accelerates in women once they reach the menopause, the time when periods are lost. That starts around age 45 to 50. Bone loss speeds up in women because women greatly reduce their production of estrogen, the major female hormone, when women no longer have periods. Once enough bone is lost, both women and men may suffer fractures, especially in the hips and spine, that could lead to permanent disability or death. Bone is very important in our bodies. It is not an inactive organ but has major functions. The functions of bone include:
- Mechanical functions: bone protects internal organs, gives shape to the body, permits movement and carries sound (bones in the ear transfer sound to the brain)
- Synthetic functions: bone contains marrow, where blood cells are made
- Metabolic functions: bone stores calcium and phosphorus, stores growth factors, keeps the acidity of the blood more normal, stores toxins that would damage our bodies and produces hormones that have many important functions including regulation of the blood sugar.
Vitamin D has a very important role in the building up and preservation of bone. Bone is in a constant state of building up and breaking down. When we are younger, building up takes precedence over breaking down, but when we get older, and especially in women at menopause, breaking down becomes more prominent and bone is lost. The key is to build up a lot of bone during our youth so that there is plenty available when we get older.
Vitamin D promotes the uptake of calcium from the intestine. It is calcium in combination with phosphorous that produces the hard mineral that makes up bone. You need about 1,000 milligrams of calcium in your diet with enough vitamin D (about 2,000 international units daily) to provide adequate calcium for your bone. Calcium plays very important roles in the body, so your body makes sure that the calcium in the blood is always adequate. If you don’t get it from it from your diet, your body will take it out of your bones and you will lose bone.
Unfortunately, during the years when our bone should be building up, we are discouraged from getting out in the sun, the best source of vitamin D. We are told to wear sunscreen to avoid skin cancer and premature aging of the skin. This is bad advice. A little sun exposure (perhaps 15 minutes on our arms and legs, not our face) two or three times a week during the hours when the sun is at its height (usually 10 AM to 2 PM) will prevent bone loss and preserve all the important function of bone that are described above.