Restoration and Remodeling
Ten million Americans past the age of 50 have osteoporosis, and many more have bones that are less dense than normal. In addition, four out of every ten white women past 50 years of age will break a hip, spine, or wrist sometime during their lifetime. While women are the majority of cases, men are certainly not immune to the ravages of osteoporosis.
Bones are constantly remodeling themselves. This process is very sensitive to a balance of key nutrients. Many think that insufficient calcium is the major cause of bone loss in the elderly. However, research has shown there is a whole spectrum of nutrients and other factors (such as age, genetics, and body size) that determine bone health.
The greatest time of bone loss for a woman is during menopause when a significant decline in estrogen occurs. Bone loss is about three percent a year for the first five to seven years after menopause. Thereafter, bone loss is only one percent a year.
Regular weight-bearing exercise is an excellent way to improve bone health. For example, middle-aged and elderly women who walk at least four hours a week have a 40 percent lower risk of hip fracture than those who walk less than one hour a week.
Adults are advised to consume at least 1,000 mg of calcium per day. Insufficient calcium over time can diminish bone density levels. But adequate vitamin D is also essential for utilization of calcium. The elderly have significantly greater bone density and fewer fractures when they consume adequate levels of calcium and vitamin D. Vitamin D also lowers the risk of falling by about 20 percent, since it also strengthens muscle, as well as bone. Foods fortified with vitamin D may include milk, soy milk, and some orange juices.
Lower intakes of vitamin K are associated with a higher risk of bone loss and hip fractures. Vitamin K is required for the function of osteocalcin, a major protein in bone matrix involved in bone remodeling. Good sources of vitamin K are green, leafy vegetables, such as spinach and broccoli.
People who consume more than average fruit and vegetables have denser bones and less fractures. The high levels of potassium and magnesium found in these foods help to neutralize acid in the body, and thus reduce the amount of calcium excreted. Post-menopausal women who regularly consume tofu and other isoflavone-rich soy products tend to have a higher bone density and less fractures than those not consuming soy.
Dietary factors that have a negative effect on bone health include alcohol, soft drinks, caffeinated beverages, excessive vitamin A from fortified foods or supplements, and a high sodium intake. While protein promotes calcium excretion, you can compensate for this and avoid bone loss by consuming additional calcium.
Winston J. Craig, Ph.D., R.D., is a professor of nutrition at Andrews University.
A whole spectrum of factors determine bone health.
Fruit and vegetables lower the risk of bone fractures.