Magnesium, Calcium, And Vitamin C Supplement Articles & Resources

But why worry about the disease before menopause? Because invisible and insidious bone loss can also happen well before a woman hits her late 40s and early 50s. In fact, many active, younger women have weaker bones than they realize. In a recent study involving 164 women, researchers at the University of Arkansas found that 2 percent of college-age women already have osteoporosis and another 15 percent have suffered significant losses in bone density and may be on their way to developing the brittle bone disease. "What you do earlier in life will affect your chances of developing osteoporosis," Cosman says. "It's never too late to start doing something to protect your bones, but the earlier, the better."

It's especially important to take action if you've ever fractured a bone after falling, if you're very thin, if you've gone through menopause at a relatively young age (in your early 40s), or if osteoporosis runs in your family. Recently, researchers in Iceland identified a common gene among a large number of families with osteoporosis; other researchers have identified a handful of different genes that are related to bone density or bone turnover. "There's no way we can tell which is the most important gene," Cosman says. "Clearly, the disease is inherited. It probably relates to multiple genes, not just one." In the future, these discoveries may lead to novel treatments or preventive measures for osteoporosis.

While you can't change certain facts of life such as being a woman, growing older or being of Caucasian or Asian descent--all of which increase your risk of developing porous bones--there are lots of preventive steps you can take. It's a matter of giving your bones the nutrients they need, the exercise they crave and the lifestyle habits that support, rather than deplete, their density.

BEYOND CALCIUM

Many women of childbearing age still don't get the recommended 1,000 mg of calcium daily. In fact, a recent survey by the American Dietetic Association found that while 89 percent of women believe calcium is important to their health, 45 percent 'fess up to not getting enough of the mineral in their diets. You, too? Perhaps you're not much of a milk drinker. Dairy products--including milk, yogurt, and cheese--are a superior source of calcium. And low-fat dairy products are up to 20 percent higher in calcium than whole-milk products, notes David Hamerman, MD, director of the Center for Bone Health at Montefiore Medical Center in New York.

But, sorry, being dairy averse isn't a good excuse for shrugging off the recommended amount of calcium when you can also get enough through other food sources. True, it may take a concerted effort to incorporate these other calcium-rich foods into your diet--among them kale, calcium-fortified soymilk and fortified orange juice, canned sardines and salmon--but the fact that they're also chock-full of other nutrients may make it worth the trouble.

Your other (and perhaps easiest) option, of course, is to take a calcium supplement. Which among the multitudes lining store shelves are the best? Supplements that contain calcium carbonate (such as Tums) offer more available calcium per pill but some women find they cause bloating or constipation. "Another option is calcium citrate, such as Citracal, which may be easier on the stomach," says Leslie Bonci, MPH, RD, director of sports nutrition at the University of Pittsburgh Medical Center. Another difference between the two types of calcium is when you have to take them. For best absorption, calcium carbonate should be taken with a meal, while calcium citrate can be taken with or without food. Consumption of either supplement, though, needs to be spaced out during the day. "The body doesn't absorb more than 500 mg of calcium at one time," says Bonci.

It's important to note, too, that calcium isn't the only nutrient essential to bone health. Good calcium absorption, in fact, depends on vitamin D, which increases the uptake of the mineral into the bone. Throughout much of the year, the skin produces plenty of vitamin D when it's exposed to the sun, but this may be a problem during the winter months in sun-deprived parts of the country. At those times and in those places, it's critical to consume at least 400 IU of vitamin a day from fortified foods or to take a multivitamin. (See Recipe for Strong Bones, p. 116, for sources of D and other osteoporosis-preventive nutrients.)

Vitamin K also has a role in bone health. K stimulates the production of osteocalcin, a protein that contributes to bone strength. Another player is vitamin C, which is critical to the production of collagen, the glue that holds bones together. Magnesium assists in bone formation, too, and helps maintain the body's calcium levels. And potassium contributes to the retention of calcium that's already in bones. In fact, research has found that women who consume large amounts of fruits and vegetables tend to have stronger bones than those who don't, largely because produce is rich in magnesium and potassium, among other nutrients.

While you should definitely make sure you're getting enough of these bone helpers, it's also important that you avoid megadosing on them or any other vitamins or minerals--especially vitamin A. "Excessive levels of vitamin A can interfere with calcium metabolism and utilization and increase calcium excretion, which can increase the risk of bone loss," says Bonci. To be on the safe side, limit your intake of vitamin A to 700 mcg.

As you assess the osteoporosis "preventiveness" of your diet, keep in mind that the macronutrient composition of your meals can also have an impact. Protein, in particular, is an oft-overlooked factor in bone health. "Bone is growing tissue and protein plays a role in maintaining the integrity of all the body's growing tissues," says Bonci. The trick is to consume the right amount of protein, not too much (which may leech calcium from bone) or too little (which can compromise bone maintenance). A good rule of thumb: Your body needs half its weight in grams of protein per day, which means if you weigh 150 pounds, you should consume 75 grams of protein daily--the equivalent of about 1/2 a roasted chicken breast, 4 ounces of salmon, 1/2 cup of low-fat cottage cheese and 1 ounce of whole almonds.

STRESS YOUR BONES THE RIGHT WAY

Exercise is the other half of the bone health equation. Yet not all forms of exercise are equally helpful. Weight-bearing exercise--in which you place the weight of your body on your bones through, for example, walking, hiking, jumping, or running--maintains bone density more effectively than others, notes Connie Lebrun, MD, director of primary care sport medicine at the Fowler Kennedy Sport Medicine Clinic in London, Ontario. And the more intense your weight-bearing workout is and the more impact it involves, the better it is for your bones. Activities such as running, jumping or climbing stairs are ideal for building and maintaining bone density and are a step above walking or, say, doubles tennis, which are, in turn, much more beneficial to bone health than bicycling or swimming. That's why cross training is such a good idea if your main activities are nonweight-bearing.

Keep in mind, too, that the benefits of exercise are site-specific. Rowing, for example, preserves bone density in the lumbar spine, whereas jumping maintains bone in the hips and lower legs. "The benefits are consistent with where you put the stress," Lebrun explains. But here's the hitch: You have to keep putting stress on those same areas to maintain the bone density gains you make. To wit, researchers at Oregon State University in Corvallis found that a 12-month program of progressive jumping exercises and lower-body resistance training helped women between the ages of 30 and 45 increase their bone mass--particularly in their legs--by up to 3 percent, but when the women subsequently stopped doing the exercises for six months, they lost nearly all the gains they'd made.

Resistance training--whether your resistance of choice is free weights, exercise bands, weight machines or your own body weight--is another form of weight-bearing exercise that keeps bones strong. "It has to do with the mechanical pull on the bone as the muscles contract," Lebrun explains. This is especially important for the upper body, since it's hard to place stress on these areas through other types of weight-bearing exercise. "No one knows which exercises are most helpful," Lebrun admits, "but some studies suggest that doing resistance training, using large muscle groups in the upper and lower extremities, for 30 minutes three times a week will yield improvements in bone density in seven to nine months."

When it comes to exercise, though, the key is not to overdo it. If you exercise aerobically to an extreme, you can deplete your estrogen levels at a relatively young age. As a result, your period can become irregular or altogether absent for months at a time (a phenomenon called exercise amenorrhea). It used to be thought that this happened only if you were to lose too much body fat, but experts now say it has more to do with being in a state of energy drain--burning up loads of calories through exercise without fueling your body with enough calories in the form of food. When this happens, your body probably won't produce the required amount of estrogen. How much exercise is too much? "There may be a threshold at which these hormonal changes occur," explains Anne Loucks, PhD, a professor of biological sciences at Ohio University in Athens, "and that threshold may be different from woman to woman." In other words, what constitutes too much exercise or too little food can vary from one woman to the next.

What experts do know, though, is that athletic women are particularly at risk for a syndrome called the "female athlete triad," which consists of a spectrum of disordered eating habits, amenorrhea and osteoporosis. "Endurance athletes and highly competitive athletes--such as gymnasts, ice skaters, and runners--are at the highest risk," notes Diana Lapiano, RN, a nurse-clinician at the Osteoporosis Center at the Hospital for Special Surgery in New York City. But it can even happen to devoted recreational exercisers who are overtraining to the point of fatigue.

Recently, another hormone-related factor has been found to endanger the bone health of young women: Depo-Provera, the once-a-month, injectable progesterone-only contraceptive. "It suppresses estrogen production in the ovaries, which can facilitate bone loss," Cosman explains. Whatever causes these unusually low estrogen levels--exercise, eating too few calories or Depo-Provera--the result is the same. The risk of stress fractures and the early onset of osteoporosis increases.

What's especially worrisome is that once bone mass is lost, it may be gone for good. "We don't know yet to what extent bone mass can be regained once the reproductive system is turned back on," Loucks says. In fact, a study published in Osteoporosis International found that even after their periods became normal, athletes who'd had amenorrhea continued to have low bone density eight years later.

The take-home message: Make sure you're eating enough to cover the energy you're expending through exercise and keep an eye on your period. If you stop menstruating, get checked out by a doctor promptly. After ruling out other potential problems, your doctor may suggest you take oral contraceptives as a form of hormone replacement--for the sake of your bones and your reproductive health.

BONE DEPLETERS

The good news is that if you're a health-conscious person, you've probably already managed to avoid all sorts of bad habits that can sabotage the health of your bones. The No. 1 offender: Smoking, which is a triple threat because it decreases estrogen levels, reduces levels of vitamin C and may interfere with the body's use of calcium. Also, drinking excessive amounts of alcohol (four or more drinks per day) can decrease the activity of osteoblasts, the cells that are involved in bone rebuilding. Chugging caffeine all day long (more than three or four cups per day) or consuming too much salt (6,000 mg or more a day) can trigger greater calcium excretion, too.

Severely restrictive eating habits can also take a toll on bone health. Not only will cutting way back on calories make you miss out on the nutrients you need to shore up your bones, but the it may affect your production of estrogen, says Bonci. What's more, the psychological stress of consciously restraining your eating habits could also have a deleterious effect. Researchers at the University of British Columbia in Vancouver found that women who exercise dietary restraint--meaning, they tend to obsess about everything they eat--excrete higher levels of cortisol (a stress hormone) in their urine and are more likely to have ovulatory disturbances, both of which appear to increase the risk of bone loss.

So here's the story in a nutshell: Eat well without making yourself crazy over it, take a multivitamin and mineral supplement and/or calcium supplement if you need to make up for any holes in your diet, and consistently engage in a healthy amount of weight-bearing exercise, and your chances of having strong bones over the long haul are very good. Because, ultimately, says Cosman, osteoporosis is a preventable disease. "And it's really in your 20s, 30s and 40s where you can make an impact by practicing healthy exercise and eating habits," she says. "An ounce of prevention is worth a huge amount in the long run."

RELATED ARTICLE: Research May Bear New Clues

Scientists are now exploring a bear-bones approach to preventing osteoporosis in humans. Researchers at Penn State Milton S. Hershey Medical Center and Michigan Technological University recently studied wild black bears' unique ability to rebound from the significant bone loss they experience each year during their long hibernation. The black bears hibernate almost half the year, a stint of inactivity that in almost all other species would almost certainly result in a major reduction in bone density. To the researchers' surprise, though, the bears seem to maintain steady bone density levels from year to year. In fact, their bones' strength and mineral content may actually even increase as the bears grow older.

Theories? Bears don't defecate or urinate during their long sleep, which may allow them to recycle the calcium normally lost by these acts. While the bruins do indeed lose bone mass during their hibernation, the researchers discovered that bone production remains constant and may even accelerate as the bears wake up and become active again. The scientists hope that bear studies will reveal clues as to how humans may be able to prevent osteoporosis.

--Liz Neporent

RELATED ARTICLE: Osteopenia: The Young Person's Bone Problem

If you've heard the term osteopenia--which means "low bone mass"--being batted around more often lately, it's because it's estimated that more than a fair share of young women have the condition. "Osteopenia is really common--about 20 percent of healthy premenopausal women have it," explains Felicia Cosman, MD, clinical director of the National Osteoporosis Foundation. "It's not a disease in itself and it doesn't need to be treated unless it's very low, but you want to watch it."

Osteopenia reflects a measure of bone density that lies somewhere between what's considered normal and what's considered osteoporotic for a woman's age. It's often thought of as a precursor to osteoporosis, but osteopenia doesn't have to result in that diagnosis: While the tendency to have it may be somewhat genetic, it can also be modified by your dietary and lifestyle habits.

The trouble is, because osteopenia doesn't cause symptoms and because premenopausal women generally don't have bone mineral density tests, many women have no idea that they have the condition. Complicating the matter, insurance plans won't cover the cost of a preventive bone density scan unless there's a medical reason for a premenopausal woman to have one. But there are times when having your bone density tested may be warranted. Among them: if you've had multiple fractures in your life; if you have a medical condition such as Crohn's disease or rheumatoid arthritis or if you take medications such as corticosteroids (for asthma, inflammatory bowel disease or autoimmune diseases), anticonvulsants (for seizure disorders) or GnRH agonists (for endometriosis); if you have irregular periods; or if you've had anorexia.

According to the National Osteoporosis Foundation, the best test is a DEXA (dual energy X-ray absorptiometry) scan, which measures bone density, usually in the hip or spine. If you discover that your bone density is low, it's imperative to address the problem right away. "The aim is to slow down the rate of bone loss." says David Hamerman, MD, director of the Center for Bone Health at Montefiore Medical Center in New York. "A person can remain osteopenic without having it progress to osteoporosis."

RELATED ARTICLE: Recipe for Strong Bones

There's no one nutrient or workout that will give you strong bones. Rather, osteoporosis prevention requires several ingredients. Here's the list*:

Calcium -- 1,000 mg a day

Best sources: dairy products, fortified orange juice and soy milks, canned sardines and salmon, broccoli, kale and other dark leafy greens

Vitamin D -- 200 IU a day

Best sources: fortified milk and cereals, salmon

Vitamin K -- 90 mcg a day

Best sources: Swiss chard, spinach and other dark leafy greens

Vitamin C -- 75 mg a day

Best sources: citrus fruits and juices, cantaloupe, strawberries, red peppers, broccoli

Magnesium -- 310 mg a day (to age 30); 320 mg a day (after age 30)

Best sources: nuts, sunflower seeds, whole-grain breads, spinach, dried beans

Potassium -- g a day

Best sources: milk, yogurt, bananas, baked potato with skin, avocado, tomato and orange juices.

Protein -- Half your body weight in grams (. 150 pounds, 75 grams)

Best sources: lean meats, seafood and poultry, dairy, nuts and seeds, eggs

Resistance training -- Using large muscle groups in the upper and lower extremities for 30 minutes, three times a week.

Weight-bearing cardio -- 45 minutes to an hour, three time a week.

* Recommendations are for women under age 50.

Stacey Colino is a writer who specializes in health, nutrition and psychology who lives in Chevy Chase, Maryland.