Your Stay-Strong Plan.

        Nobody expects to break a bone. As we race through our happily hectic days, we take for granted the 206 bones in our skeletons. But when one snaps, everything changes. A break may mean doctors' appointments, x-rays, a cast, or even surgery, physical therapy, and months of limited mobility. And if you're over 40, you may also worry that this fracture will be just the first of many to come.

        What you fear is osteoporosis, the disease that leaves bones brittle and prone to fractures. It often occurs in the first few years after menopause, when bone loss accelerates due to dropping estrogen levels. A matrix of minerals, bone is constantly broken down and rebuilt by the body at a microscopic level: If the breakdown consistently exceeds the buildup, bones lose density.

Eight million women and 2 million men age 50 and older have osteoporosis, and some 34 million more Americans have osteopenia, a stage of bone decline that occurs before full-blown osteoporosis.

But even in midlife and beyond, women can still prevent bone disease. Read on forPrevention's bone-protection plan.

Stay Stronger Longer
        The most effective way to protect your bones is to make sure you're getting enough calcium, vitamin D, and protein, whether it's through food or with the help of supplements. Even though you reach your bone-building peak around age 30, getting the right amounts of these key nutrients throughout your life is crucial to keeping your skeleton healthy. Here's the latest expert advice on where to start.

Calcium
What you need: 1,000 mg a day for women ages 19 to 50; 1,200 mg for those over 50, per the Institute of Medicine (IOM). This mineral is the single most important component in building and maintaining bone density.

Where to get it: Dairy products—especially fat-free or low-fat milk and yogurt—are excellent sources and account for about 72% of Americans' calcium intake. (If you're lactose intolerant, lactose-free products provide calcium too.) Other great sources include canned sardines and salmon, calcium-fortified orange juice and dry breakfast cereals, Cheddar cheese, and tofu (if prepared with calcium sulfate). Check out this handy chart of the beat food source of calcium. 

Supplemental sources: Your body can handle only about 500 to 600 mg of calcium in one 6-to 8-hour period and absorbs only about 30% of that. If you consume only 1 or 2 cups of milk and/or yogurt daily, you'll come closer to meeting your daily requirements if you also take a daily supplement that provides 500 mg of calcium citrate or 600 mg of calcium carbonate, according to Ethel Siris, MD, director of the osteoporosis Calcium carbonate should be taken with meals for best absorption, but calcium citrate can be taken at any time of day.

Can you take too much? While it's not a common problem, the IOM warns against consuming too much calcium. At elevated levels, the mineral can cause kidney stone and was linked in one major study to a slightly heightened risk of heart attack. It's not connected, however, with the "calcifications" that may turn up on mammograms. The IOM sets the upper limit of safety for women over 50 at 2,000 mg of calcium a day.[pagebreak]

Vitamin D
What you need: 600 IU daily for people ages 1 to 70; 800 IU above age 70, according to the IOM

Where to get it: You can't absorb calcium without vitamin D, which can sometimes be found in the same sources, such as dairy products (a glass of vitamin D-fortified milk has about 120 IU). Additionally, it's in fatty fish such as salmon and mackerel, egg yolks, and D-fortified breakfast cereals. Vitamin D is also synthesized by the skin when sunlight touches it, but if you use sunscreen, have very dark skin, or live in a cloudy climate, you may be limited in how much your body can manufacture.

Supplemental sources: A blood test can confirm if you're not getting enough D. If you need more, Dr. Siris recommends a supplement with 400 IU of vitamin D (as cholecalciferol).

Can you take too much? The IOM also sets an upper limit (4,000 IU daily) forvitamin D, but it's best to stay well under that. Unless you're diagnosed with a severe deficiency, avoid supplements greater than 1,000 units a day. 

Protein
What you need: Up to 77 g a day for a woman who weighs about 154 pounds, according to a 2010 multiuniversity study published in Aging Health. While the RDA for a woman of this weight is 56 g, the research suggests that another 21 g a day can improve bone strength. When you increase dietary protein, you increase calcium absorption and a natural growth factor called IGF-1, which is important for bone formation.

Where to get it: Poultry, lean meats, fish, beans, tofu, and fat-free or low-fat dairy products all pack protein. For a sense of how much: Three ounces of cooked beef has about 28 g of protein, 3 ounces of sardines has 21 g, a cup of lentils has 18 g, and a cup of yogurt has 14 g.

Power Foods For Bone Health
Here are some easy ways to get the key bone-protecting nutrients:

Protein
Cheese includes both calcium and protein
3 ounces of fish can pack in a full 21 g of protein

Calcium
        Tofu prepared with calcium sulfate is a good nondairy source of the mineral
8 ounces of fat-free plain yogurt has 452 mg of calcium
Orange juice is often fortified with calcium
A cup of low-fat milk provides 305 mg of calcium

Vitamin D
An egg yolk contains 10% of your dailyvitamin D
Some cereals are enriched with both calcium and vitamin D

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Your Density Destiny
        The gold standard for assessing bone health is a test called DXA (for dual-energy x-ray absorptiometry). The completely painless 10-minute scan typically measures bone-mineral density in the hip and lower spine.

Many women can wait until 65 to have the procedure, according to Sundeep Khosla, MD, a bone specialist at the Mayo Clinic in Rochester, MN, and there's no need for most women to get a baseline test prior tomenopause, he says. But if you're at high risk, you should get the test sooner—within 3 years of menopause, at the latest.

The scoring for the test is based on the average bone density of a 30-year-old woman, whose T-score, as it's called, is zero. If your T-score falls between-1 and-2.5, your diagnosis will be osteopenia, which you should take as a wake-up call to do all you can to preserve your bones and try to prevent the development of osteoporosis. If your score is-2.6 or lower, you're considered to have full-blown osteoporosis.

Are You At Risk For Osteoporosis?
Everyone's odds of osteoporosis increase with age: The older you get, the more likely you are to develop the disease. But many other factors can also affect your chances—and some of them are within your power to change. Below, some of the most common contributors to osteoporosis risk:

• You have a family history of osteoporosis (among men or women on either side).
• You've already had a low-impact fracture (a break caused by only a mild trauma).
• You were treated for at least 3 months at any point in your life with oral steroids (which weaken bones).
• You've got a bone-robbing disease such as rheumatoid arthritis.
• You had an early or abrupt menopause(which can result from chemotherapy or removal of ovaries), lowering your estrogen levels.
• You consume too much caffeine (more than 375 mg, or about 4 cups of coffee a day), salt (more than 2,300 mg daily), or alcohol (more than one drink for women per day; more than two per day for men).
• You smoke.