Bone building is a complex process that involves minerals and hormones that can be greatly influenced by dietary factors.

The bone thinning condition called osteoporosis can lead to small and not-so-small fractures. Although many people think of calcium in the diet as good protection for their bones, this is not at all the whole story. To protect your bones you do need calcium in your diet, but you also need to keep calcium in your bones.

How to get Calcium into your bones? Get calcium from greens, beans, or fortified foods. The most healthful calcium sources are green leafy vegetables and lefumes. Broccoli, Brussels, sproouts, collards, kale, mustard greens and other greens are loaded with highly absorbable calcium and a host of other healthfull nutrients. The exception is spinach, which contains a large amount of calcium but tends to hold into it very tecaciously, so that you will absorb less of it.

Dairy products do contain calcium, but it is accompanied by animal proteins, lactose sugar, animal growth factors, occasional drugs and contaminants, and a substantial amount of fat and cholesterol in all but the defatted versions.

Exercise: Exercise is important for many reasons, including keeping bones strong. Active people tend to keep calcium in their bones, while sedentary people lose calcium.

Vitamin D: Vitamin D controls your body's use of calcium. About 15 minutes of sunlight on your skin each day normally produces all the vitamin D you need. If you get lettle or no sun exposure, you can get vitamin D from any multiple vitamin. Vitamin D is often added to milk, but the amount added is not always well controlled.

Reduce Calcium losses by avoiding excess Salt: Calcium in bones tends to dissove into the blood-stream, then pass through the kidneys into the urine. Sodium (salt) in the foods you eat can greatly increase calcium loss through the kidneys. If you reduce your sodium intake to one to two grams per day, you will hold onto calcium better. To do that, avoid salty snack foods and canned goods with added sodium, and keep salt use low on the stove and at the table.

Get protein from plants: Animal protein---in fish, poultry, red meat, eggs, and dairy products--tends to leach calcium from the bones and encourages its passage into the urine. Plant protein--in beans, grains, and vegetables--does not appear to have this effect.

Don't Smoke: Smokers lose calcium, too. A study of identical twins showed that, if one twin had been a long-term smoker and the other had not, the smoker had more than a 40 percent higher risk of fracture.

Hormone supplements have serious risks: Some doctors recommend estrogen supplements for women after menopause as a way to slow osteoporosis, although the effect is not very great over the long run, and they are rarely able to stop or reverse bone loss.

Reversing Osteoporosis: If you already have osteoporosis, you will want to speak with your doctor about excercises and perhaps even medications that can reverse it.

Osteoporosis in men: Osteoporosis is less common in men than in women, and its causes are somewhat different. In about half the cases, a specific cause can be identified and addressed: Steroid medications, such as prednisone, are a common cause of bone loss and fractures. If you are receiving steroids, you will want to work with your doctor to minimise the dose and to explore other treatments.

Alcohol can weaken your bones, apparently by reducing the body's ability to make new bone to replace normal losses. The effect is probably only significant if you have more than two drinks per day of spirits, beer, or wine.