Calcium alone does not a strong bone make. Here is a sampling of the supporting cast behind bone building:

Boron: Increases calcium absorption, reduces the amount of calcium excreted in urine and even helps raise estrogen levels. Get boron from fruits such as apples, grapes, pears and peaches, as well as nuts and beans.

Vitamin A: For metabolizing calcium; people deficient in vitamin A often wind up with too much calcium in the blood, due to bone being reabsorbed. Get vitamin A from carrots, collard greens, spinach and sweet potatoes.

Vitamin D: D promotes calcium absorption. Get vitamin D from avocado, fortified cereals, rice, vitamin-enriched cow's milk, soy, sardines, salmon, herring and mackerel.

Magnesium: Needed to absorb Vitamin D. Get magnesium from beans (black, white, kidney), tofu, almonds and cashews.

Vitamin K: Vitamin K allows osteocalcin—the bone protein that binds calcium to its scaffold—to do its work. Get vitamin K from dark, leafy greens like broccoli and spinach.

The Calcium Conundrum

If you don't get enough of the stuff from diet alone, here's how to narrow down over-the-counter selections.

Form matters: To get the right amount of calcium, form matters. Calcium citrate is the most easily absorbed type of calcium, while calcium carbonate supplements have the most calcium by weight and are generally the least expensive. Calcium carbonate needs to be taken with food; calcium citrate does not.

Find a brand you trust: Use known brand names such as Caltrate and Viactiv with proven reliability to be sure you're getting a pure, standardized supplement.

Don't overdo: If your supplement contains more than 500 mg of elemental calcium, you're probably wasting your money. There's only so much calcium your body can or will absorb. Spread out your supplements over the day to get the most bang for your bone.

Tagalongs: Although vitamin D, magnesium and phosphorus are important for calcium absorption and metabolism, it's best to try to eat a balanced diet and/or take a daily multivitamin.