ATLANTA, Georgia (CNN) -- If you want to stand up tall when you're old, you might want to start when you're young. While osteoporosis, or thinning of bone density, usually hits most women after they have gone through menopause, there are steps they can take in their early years to lessen just how much bone they eventually lose.
The most important factor in bone health is genetics, according to Dr. Roberto Pacifici.
Women between the ages of 12 and 20, the prime bone-growing years, should be aware of what makes their bodies, and specifically their bones, stronger or weaker. The most important factor in bone health is genetics, according to Dr. Roberto Pacifici, chief of edndocrinology at Emory University, so with a chuckle, he advises women "to make sure they choose healthy parents."
But after that, Pacifici says, young women need to make sure their estrogen production levels are normal, first by making sure they are having normal menstrual periods, which is usually achieved by proper nutrition. Second, by avoiding certain medications that inhibit estrogen production, such as steroids and cortisone.
A low body weight is also a factor in skeletal growth. While a small group of women will have a low body weight because of eating disorders, serious athletes make up the larger group at risk -- for example, competitive runners or gymnasts. We all know physical activity is good, but excessive physical activity can be unhealthy.
So, the CliffsNotes version of strong-bone guidelines for those age 12 to 20 is:
• Normal body weight
• Normal periods
• Normal types of medication
• Normal physical activity
As women mature from 20 to around 50 years old, things change and the guidelines become more like a favorite family recipe: A little of this, a little of that. Pacifici urges moderate alcohol intake: "Two drinks a day being moderate, over three would be considered excessive," he says. He believes the best way for women in this age-group to keep their bones strong is to keep their body weight within normal levels and make sure they are exercising regularly. Watch more on preventing bone loss »
At this stage, women need to start taking a calcium supplement, which the National Osteoporosis Foundations puts for women under 50 at 1,000 mg per day. The one thing Pacifici says is essential for women during this time is that they "get sufficient amounts of vitamin D." While sunlight is the easiest way for us to get our dose of vitamin D, the doctor says the awareness about the importance of sunscreen has had an "unwanted consequence and that now there are many people with a deficiency in vitamin D." We need vitamin D because it helps our bodies absorb calcium.
After the age of 50, most women will experience some bone loss. The amount will depend on how well those bones were treated up to that point. Pacifici says most women start experiencing bone loss "about three years prior to menopause," which is why doctors recommend women increase their calcium intake to 1,500 mg daily.
Since osteoporosis is a silent disease with no symptoms until bones start to fracture or break easily, the best way to detect it is to get a bone density screening. The test is done by taking an X-ray of a woman's lower spine and hip area with a detection device that reads out the level of bone density. The screening can be done at any time, but anyone in a high-risk category -- with a family history of osteoporosis or frequent fractures -- should get this screening done when they go through menopause. Those not in a high-risk category could wait until a few years after menopause.
Pacifici points out the test is neither painful nor extremely expensive (he likens it to a cholesterol screening). He says it's an important tool "because in the end it might just tell you and your bones not just where, but also how straight you are going to be able to stand in the future." E-mail to a friend