But this protective system has many flaws. The calcium in your bones declines at a rate of about 1 to 3 percent per year. Counterstrategies may modify this. For instance, countries whose inhabitants consume more dairy products also have citizens with more calcium in their bones. But diet is only a part of the story.
Fractured hips are a disease of inactivity and diminished calcium intake.
Twenty-five million Americans have osteoporosis. Women are particularly at risk, having three to five times as many problems from weak bones as men. The recommended dietary allowance for calcium is 1,500 milligrams per day, the equivalent of three glasses of milk. Even early in life, however, most of us don't reach this ideal, so bone loss starts frequently in the 20s, but does not become pronounced enough to result in fractures until the 70s and beyond. Unfortunately, calcium intake tends to decrease as you grow older.