4 Bone-strengthening foods can be found in the produce aisle

When it comes to warding off osteoporosis, lowfat dairy gets most of the credit for its high calcium content. But your skeleton requires a supporting cast of nutrients to stay strong: A study published in the Journal of Bone and Mineral Research found that women who consumed the most vitamin C had higher bone densities than those who got the least. So the next time you head to the supermarket, stock up on foods rich in the vitamin, such as citrus fruits, broccoli, and red peppers.

While you're at it, toss some kale, spinach, or Swiss chard in your shopping cart. These vegetables are all high in vitamin K, which boosts production of osteocalcin, a protein that binds calcium to bone tissue. And don’t skip the seafood aisle. Yellowfin tuna is rich in magnesium, another must for strong bones; nearly 50 percent of your body’s store of this mineral is found in your skeleton. Each day, aim for 320 milligrams of magnesium, which is also found in brown rice and peanut butter.

All the milk, yogurt, and supplements in the world won't do a body a bit of good unless you’re getting vitamin D along with your calcium. "Calcium is reliant on vitamin D," says Susan E. Brown, Ph.D., director of the Osteoporosis Education Project in East Syracuse, New York. "Without sufficient vitamin D levels, very little of the calcium you consume will actually be absorbed and useful to the body."

You need 1,000 to 1,200 milligrams of calcium a day—the amount in three to four servings of lowfat dairy—and at least 400 to 800 international units of vitamin D, according to the National Osteoporosis Foundation guidelines. Find the vitamin in salmon, shrimp, and fortified milk or orange juice. While 15 minutes of unprotected sun exposure is another good source of vitamin D, you also run the risk it will damage your skin and lead to cancer.

Because the average American falls short on vitamin D, experts recommend taking a pill daily. There are two forms of the supplement, D2 and D3. "Opt for the D3 version, which is more effective," says Robert P. Heaney, M.D., an osteoporosis researcher and professor of medicine at Creighton University.

You poured nonfat milk over your raisin bran at breakfast this morning, then sprinkled cheese on your spinach salad at lunch, so you're well on your way to meeting your calcium quota, right? Maybe not. Certain chemicals, such as oxalates (found in spinach and rhubarb) and phytates (in wheat bran and beans), bind to calcium, blocking its absorption. So don't factor all of the calcium you consume with these foods into your daily total. Having a diet high in processed foods can also set you up for calcium loss. "They're usually sky-high in sodium," says Felicia Cosman, M.D., clinical director for the National Osteoporosis Foundation. "And when your kidneys excrete excess sodium, some calcium is swept along with it." She recommends limiting your intake to less than 2,000 milligrams a day by choosing low-sodium foods and cutting back on packaged goods. A cup of soup, for example, can pack in nearly 900 milligrams of sodium, while two tablespoons of French dressing contains 250 milligrams.