PHILADELPHIA (WPVI) -- Osteoporosis, sometimes known as brittle bone disease, takes years to develop.
But there are things anyone can do early on to head it off.
Reading tutor Linda Zager says she's always been strong and active.
A routine screening around age 60 showed signs of weak bones, but she didn't think much of it.
"I fell any number of times rollerblading," said Zager. "I never broke anything."
Around 75, she developed bad back problems.
"I started having this awful pain," she said. "I couldn't actually stand up."
As it turned out, Zager had four compression fractures in her spine.
Dr. Heidi Syropoulos of Independence Blue Cross says brittle bones develop silently.
"People do not feel osteoporosis until they've had a fracture," she said.
Throughout the world, 1 in 3 women develop weak bones. 1 in 5 men have it.
It's more common in Caucasian women of northern European descent. And it does run in families.
Lifestyle plays a role, too.
"You see it in general in people who smoke, people who use steroids, people who drink a lot, and people that are sedentary, people who don't exercise," said Dr. Syropoulos.
Bone density scans are important for women after menopause.
Most experts now agree mid-60s is a good time to start for those with an average risk. But women and men shouldn't wait to protect their bones.
From late teens onward, get 1,000 milligrams of calcium and 600 units of vitamin D a day in your diet, preferably from dairy products.
"And if you don't like dairy," says Dr. Syropoulos, "or can't tolerate dairy, there are definitely other foods you can get, like green, leafy vegetables."
And get lots of weight-bearing exercise - at least 45 minutes, 4 to 5 times a week.
"Walking, running, ice skating, anything like that," the doctor says.
Dr. Syropoulos says to start slow, then build time and intensity.
Zager takes a class targeting muscle and bone strength as well as balance. But she wishes she'd started sooner, because she's lost something forever: her height.
"When I graduated from high school, I was 5'7"," she says. "As of when I was 75, I was 5'5 1/2". I'm now 5'3".
Send a breaking news alert
Report a correction or typo
Learn more about the 6abc apps
Healthcheck: Age Fearless - Preventing osteoporosis