Today is the day to begin preventing osteoporosis, an age-related disorder in which bones become gradually thinner, more porous and less able to support the body.

This condition attacks both men and women, but women usually suffer more severely because bone loss accelerates rapidly after menopause. By the time a woman reaches the age of 70, she may have lost as much as 30 percent of her bone density.

Prevention is the key

The following lifestyle-related factors may lead to the development of osteoporosis:

	lack of exercise
	calcium and vitamin D deficiency
	prolonged use of drugs, alcohol, caffeine, high-phosphate soft drinks
	smoking

The good news is that osteoporosis may be prevented by a combination of exercise and good nutrition. Here's how:

Get plenty of exercise:

Weight-bearing exercises can help prevent bone loss and may encourage bone growth. Specific exercises to twist, bend, stretch and compress bones are needed to strengthen the common sites at risk: the upper arm at the shoulder, the forearm at the wrist, the thigh bone at the hip, and the spine. This process is known as ''bone loading.''

Before beginning any exercise program, always consult your physician. If you're given the go-ahead, start slowly and build up over time. An ideal program should include bone-specific, aerobic weight-bearing exercise three days per week. Weight-bearing exercise includes such activities as walking and cross-country skiing.

Include a variety of exercises that will stimulate as many different bones as possible. Add upper-body muscle strength and endurance training two days per week.

Stick with your program and work up to working out at least 20 to 30 minutes a day, three times per week. Also, think about ways to increase your daily activity, such as taking the stairs or gardening.

Eat for stronger bones:

You can bolster your bone strength by eating a high-calcium, high-fiber, low-fat diet.

Did you know that two-thirds of your bone is composed of calcium? Here are the recommended dietary allowances (in milligrams per day) for calcium for various individuals:

	18-50 years: 800 mg
	pregnant or lactating women: 1,600 mg for mothers under age 19, 1,200 mg for mothers over age 19
	women over 50: 1,000 - 1,500 mg
	men and women over 60: 1,000 - 1,500 mg

You need vitamin D to help metabolize calcium. The best source of vitamin D is the sun, but fortified milk products offer the same benefit without the risk of skin damage.

You can also get a good dose of calcium from the following sources:

	nuts, seeds, beans and peas
	fish with bones
	green vegetables

Bones to last a lifetime

Bone-loading exercise and a balanced diet are important components for preventing osteoporosis. By taking care of your bones now, they will stay strong enough to carry you safely through a lifetime of health and activity.