Every time a child drinks soda, he's laying the groundwork for a dangerous bone disease. No, fizzy and sugary drinks don't cause osteoporosis. But because they're often a substitute for a glass of milk, kids are coming up short of the calcium and vitamin D they need to build a strong skeleton. Many of them also lead a sedentary lifestyle, so they aren't getting the bone-building benefits of vigorous exercise either. These children aren't just in jeopardy for brittle bones and fractures decades down the road: They could be at risk of osteoporosis at a younger age than ever before.

That's a problem every parent should be concerned about, says Leon Root, MD, author of Beautiful Bones Without Hormones, and professor of clinical orthopedics at Weill Medical college of Cornell University in New York City. "Osteoporosis is actually a childhood disease that manifests itself later in life." The condition causes bones to become riddled with holes, like the frame of a house that's been attacked by termites. That can lead to broken bones, which in turn can cause deformity, chronic pain or disability. Osteoporosis can even be fatal: 20 percent of older people who suffer a broken hip die within a year.

Osteoporosis isn't just your grandmother's health threat. Although it strikes about eight million women in the United States, it also menaces two million men. Another 34 million Americans have low bone mass, yet most aren't even aware that there's an epidemic in the making, says Surgeon General Richard H. Carmona, MD, who released the first-ever Surgeon General's report on osteoporosis last October. "You don't see TV shows about osteoporosis, and it's not in the headlines. But by embracing prevention, we could save thousands of lives."

There's a new medical understanding of the best ways to protect ourselves--and our children. "Simple lifestyle changes can save your bones, which can save your life," says Dr. Root. "And it's never too soon--or too late--to take action."

The Calcium Connection
Contrary to popular belief, the skeleton isn't a rigid and unchanging structure. Each year, our bodies re-place about 20 percent of our bones' spongy tissue, which means that our activities at every age influence their health. Sections of old bone break down, creating gaps to be filled by new bone. Until about age 30, we build bone very efficiently, so making the right health moves, such as exercising and getting enough calcium, helps your skeleton reach its genetically determined peak strength.

Think of your bones as a retirement fund: The more you deposit when you're young, the better off you'll be in later years, when you need to draw on your reserves. But most kids don't bank nearly enough calcium. Only one in five girls ages 9 to 19, and about half of boys, get the RDA of this bone-building mineral. That's frightening, since 90 percent of accumulated peak bone formation occurs before age 20. The effects of being shortchanged on calcium go beyond an increased risk of osteoporosis in the future. There may be a price to pay much sooner: A recent Mayo Clinic study reports an alarming rise in children's forearm fractures, compared with rates 30 years ago.

Giving kids a calcium boost may help ward off painful injuries. In a 2005 study at Ohio State University Medical Center, doctors tracked the skeletal growth of girls, ages 8 to 13, over a seven-year period. All of them averaged about 800 mg of calcium from their diet--far less than the RDA of 1,300 mg for their age group. Half of the girls received calcium supplements, while the other half didn't. "We saw powerful benefits to getting extra calcium, especially at puberty when children have a major growth spurt," says Velimir Matkovic, MD, lead author of the study and director of OSUMC's Osteoporosis Prevention and Treatment Center. Not only did the supplemented group develop stronger bones, but they had half the fracture rate of the other girls in the study.

Do all children need supplements? Ideally, kids and adults should get their daily calcium quota through a healthy diet. Got milk? Dairy products of all types will do the trick. Other good sources include sardines or canned salmon with bones, leafy green vegetables, soybeans, and calcium-fortified orange juice, cereal, or breakfast bars. Encourage your children to have three to five servings of these bone-builders daily. And if they shun milk because they think it's fattening, let them know the latest research shows the opposite is true: Kids with the highest milk consumption are also the slimmest, while those who drink the most soda or other sweetened beverages, unsurprisingly, are the heaviest.

Since most people don't consume enough calcium, supplements can fill the gap, says Dr. Matkovic. "There are several types, and all of them do a good job. Flavored, chewable tablets are more appealing to children, making it more likely that they'll actually take them." In his study, girls were given 1,000 mg a day, half in the morning and half at night, since calcium is best absorbed in amounts of 500 mg or less at a time. That's also a safe dose for adults whose diets are lacking in this bone-building mineral. Supplements can interact with some drugs, so check with your doctor or pharmacist.

What 'D' Can Do
Are you getting enough vitamin D? There's a growing scientific consensus that the current guidelines of 200 IU for adults under 50, and 400 or 600 IU for older people, are too low. That's bad news for our bones, since this vitamin is crucial to processing calcium efficiently, says Robert Heaney, MD, professor of Medicine at Creighton University in Omaha. In a 2003 study, he compared the effects of giving postmenopausal women vitamin D supplements one year, followed by one year of no supplements. The result? When the women had higher vitamin D blood levels, they absorbed 65 percent more calcium.

Dr. Heaney and other experts are advocating a rise in the RDA for this nutrient. "Getting too little has been linked to many chronic disorders, from osteoporosis to type 1 Diabetes and even cancer, so deficiency is a huge health threat," says the doctor, who believes that the best protection is taking 1,800 IU daily.

Part of the problem is that this nutrient is found in relatively few foods, says Dr. Heaney. And while people can also get the vitamin naturally, through sun exposure, that's not always possible or even a good idea, especially if you're prone to sunburn. "We've just shown that in the northern United States, outdoor workers make plenty of vitamin D in the summer," says Dr. Heaney, "but it doesn't last through the winter, when the sun is lower on the horizon." Studies also show that skin production of the vitamin dwindles in older people, even if they're sun-worshipers, suggesting that a supplement might be the best way to safeguard their bone health.

Use It or Lose It
As you age, you lose bone faster than you produce it. Over the five to seven years after periods stop, women can lose up to 20 percent of their bone mass due to estrogen deficiency. Paying extra attention to bone health can lessen the damage, however. Men are also affected by age-related skeletal loss, but not as dramatically, since their larger frames provide a higher peak bone mass and their hormones don't plunge after age 50. Our skeleton needs regular exercise at every age to stay strong, but we're becoming a nation of lazybones. The Surgeon General reports that about half of adults--and kids--don't do the minimum to keep their bones fit: 60 minutes of physical activity a day for kids and 30 minutes for adults. A combination of weight-bearing routines (such as walking, jogging, stair-climbing, or dancing, plus resistance exercises like weight-lifting) is the ideal recipe for bone health.

For children, jumping is a fun way to bone up, a 2003 study at University of British Columbia found. The researchers contrasted elementary school girls who took gym classes to those who also did ten minutes of high-impact jumping exercises, three times a week. At the end of the two-year study, the exercise group had a nearly five percent jump in bone mass. Other weight-bearing exercises with kid appeal include jumping rope, tennis, in-line skating and team sports, such as soccer.

Getting in shape pays off at every stage of life, says Ethel Siris, MD, director of the Toni Stabile Osteoporosis Center at New York Presbyterian Hospital/Columbia University Medical Center. "It's enormously valuable for kids and young adults, because they're still building bone mass. If you're in your 30s or 40s, it helps you hang on to what you have." Research shows that weight-bearing exercise, in part, can undo the bone-damaging effects of menopause. Even at 80, when the risk of fractures is very high, exercise is still worthwhile, because physically fit older people are less likely to fall and break a hip. To get Americans moving in the right direction, Dr. Carmona says, "I'm challenging everyone, the public and doctors, to work together to improve bone health. Millions are at risk for fractures, and it's all preventable. This is an epidemic that doesn't have to happen."