How to Keep Your Skeletal System Healthy

It’s not every day that scientists find an easy, painless way to cut your chances of a debilitating disease in half. But for osteoporosis—the brittle bones of old age—that’s exactly what they’ve done. We now know that just by maintaining a calcium-rich diet from childhood onward, you can dramatically improve your odds of escaping the disease. Characterized by loss of bone density and strength, osteoporosis affects 10 million Americans. Another 18 million have thinning bones, placing them at risk for developing osteoporosis. The disease is the major underlying cause of bone fractures in postmenopausal women and the elderly.

Osteoporosis-related fractures can occur in any bone, but the most common sites are the spinal column, the wrist, and the hip. Rapid loss of bone mass begins to occur in a woman’s spinal column following menopause. When the loss becomes great enough, a simple action, such as bending forward while making a bed, can cause enough pressure to produce a spinal compression fracture, resulting in chronic pain, loss of height, and a characteristic “dowager’s hump.” Wrist fractures also occur commonly among women with osteoporosis.

Hip fractures in the elderly are one of the most serious health problems in the U.S. Broken hips are associated with more death, more disability, and higher medical costs than all other osteoporosis-related fractures combined. Up to 20 percent of older adults die within a year of breaking their hips due to osteoporosis. Of the survivors, fewer than half return to the full level of activity they previously enjoyed.

Other factors that increase your risk of osteoporosis, which can affect not only postmenopausal women but all elderly women and men, include:

Age. Although denser bones delay the onset of osteoporosis, normal aging inevitably includes some gradual loss of bone.

Gender. Osteoporosis is estimated to be six to eight times more common in women than in men because women’s bones are usually less dense to begin with, and because the lower estrogen levels that accompany menopause cause women to lose bone mass much more rapidly.

 

Inside a Brittle Bone

When the life-long process called bone remodeling slows, calcium leaches out faster than bone cells can restore it. The result is an increasingly porous skeletal structure given to tiny fractures you may never notice. As the disease progresses and bone density declines, major fractures of the hip, spine, or wrist become ever more likely

 

Early menopause (before age 45). The sooner estrogen levels drop, the greater the chances of developing osteoporosis. Either a naturally early menopause or surgical menopause (removal of the ovaries) can be at fault.

Ethnic background. Asian and Caucasian women and men are at greater risk than African-Americans, whose bone mass is generally about 10 percent greater.

Lack of weight-bearing exercise. The significant loss of bone mass in astronauts (who spend considerable time in a weightless environment) demonstrates the importance of weight-bearing exercise—particularly walking—in maintaining strong bones.

Body weight. Thin, small-boned women—particularly female athletes, such as gymnasts and runners, who exercise so strenuously that their periods cease—face a heightened risk of developing osteoporosis even as young adults. Specifically, an adult weight of less than 127 pounds and a lack of menstrual periods for more than a year increase your risk of developing osteoporosis, according to the National Osteoporosis Foundation.

Heredity. A history of broken bones or stooped posture in older family members—especially women—can be a warning that you too are at risk.

Alcohol and smoking. Heavy drinkers and smokers have weaker bones. Alcohol disrupts bone formation. Smoking decreases absorption of calcium.

Osteoporosis also may occur as a side effect of prolonged use of thyroid hormones, anticonvulsants or steroid drugs. Hyperthyroidism, rheumatoid arthritis, kidney disease, and certain cancers, such as lymphoma and leukemia, can also lead to osteoporosis.

Medical researchers still don’t know why, given identical chances, one person develops osteoporosis while another doesn’t. Nevertheless, they have learned a great deal about how to prevent the disease. In fact, the good news is that if your bones reach their maximum density (or mass) by the time you are 30, and if you take steps to curb the rate of natural bone loss in later life, you slash your risk of developing the condition.

A vast body of research has now confirmed the need for adequate calcium intake during early life to build denser, stronger bones and during later life to slow down the rate of natural bone loss. Although everyone experiences some bone loss with age, osteoporosis and disabling bone fractures are not a normal part of aging.

Why the Fuss over Calcium?

Bone is living tissue that is continually being broken down, or resorbed, and rebuilt. This process is called remodeling. Nearly all of the calcium in your body is stored in your bones and teeth. Calcium not only makes your bones hard but performs such essential functions as helping your blood to clot and enabling your heart and other muscles to contract. Whenever your dietary intake of calcium is too small to meet your body’s needs, increased amounts are drawn from the bones to maintain a relatively constant supply in the bloodstream.

Human bone grows most rapidly throughout childhood and adolescence. More than one-third of total adult bone mass develops between the ages of nine and 18. During your 20s, bone growth increases by approximately 15 percent. Peak bone mass—when bones are their strongest—occurs between the ages of 25 and 35. After that, bone mass gradually diminishes and your bones begin to lose their strength.

Your bones are in constant flux. Certain hormonal signals prompt the breakdown of old bone, while others encourage new bone deposits. When you are young, old bone is replaced by new bone every 90 days. Once you attain peak bone mass, the rate of bone dissolution exceeds the rate of new bone creation, resulting in gradually decreased bone mass and density.

Millions of Americans get far too little calcium to prevent osteoporosis. Only about 25 percent of boys and 10 percent of girls ages 9 to 17 get the amount of daily calcium recommended by the Institute of Medicine (1,300 milligrams daily). Only about half of adults consume the 1,000 to 1,500 milligrams advised by the National Institutes of Health.

How Much Calcium Do You Need?

Recommended Calcium Intakes (milligrams per day)   
National Academy of
Sciences (1997)
National Institutes of
Health (1994)

Infants, Children, and Young Adults
Birth-6 months 210 Birth-6 months 400
6 months-12 months 270 6 months-12 months 600
1-3 years 500 1-10 years 800-1,200
4-8 years 800
9-18 years 1,300 11-24 years 1,200-1,500
Adult Women
19-50 years 1,000 25-50 years 1,000
51 and older 1,200 51-64 years, taking estrogen 1,000
51-64 years, not taking estrogen 1,500
65 and older 1,500
Adult Men
19-50 years 1,000 25-65 years 1,000
51 and older 1,200 65 and older 1,500
Summary of recommendations for optimal calcium intake made by the consensus development panel convened by the NIH, June 1994 and the Food and Nutrition Board of the National Academy of Sciences, August 1997. Optimal calcium intake refers to the level of calcium consumption from the diet plus supplements, if needed, that is necessary for a person to maximize peak adult bone mass and minimize bone loss in later years.

Sources: National Institutes of Health, Bethesda, MD; National Osteoporosis Foundation, Washington, DC.

 

How much does this matter? In March 2000, a panel of experts convened by the National Institutes of Health (NIH) in Bethesda, Maryland, reviewed the latest scientific data and concluded that the bone mass you build early in life is perhaps the most important factor in determining your bones’ long-term health. Strong bones provide a reserve against the accelerated bone loss that occurs when estrogen levels decline during menopause. This period of rapid loss lasts approximately six to eight years, after which the loss becomes more gradual—similar to that of aging men. To avoid depletion of bone mass and reduce the risk of osteoporosis-related fractures during midlife, the NIH panel recommended that postmenopausal women aim for a daily calcium intake of 1,000 to 1,500 milligrams. Because older adults have more problems absorbing calcium than do younger people, the panel also advised women and men 65 and older to boost their calcium intake to 1,500 milligrams of calcium daily, an amount almost double the older recommended dietary allowance (RDA). In 1997, the National Academy of Sciences boosted the RDA to similar levels for older adults.

Because there is no real cure for osteoporosis, prevention is paramount. Scientists know that, by consuming the proper amounts of calcium at the right times in life, you can minimize bone loss.

Finding Sources of Calcium

You can achieve your recommended daily allowance of calcium by eating a calcium-rich diet, choosing calcium-fortified foods, taking calcium supplements, or combining these strategies. Vitamin D enhances calcium absorption, while certain medications and foods reduce its availability.

Dietary sources of calcium are not difficult to find. Milk and milk products are naturally rich in this important mineral. They also provide vitamins A and D, protein, magnesium, and phosphorus, the other building blocks for bone. Four eight-ounce glasses of skim milk contain approximately 1,200 milligrams of calcium—roughly the recommended amount for teenagers and young adults. One study showed that 12-year-old girls who consumed just one additional glass of milk per day for 18 months developed higher total body and spinal bone mass than those who did not. Unquestionably, a glass of milk with each meal and an afternoon snack is a healthier—and often cheaper—alternative for young people than sodas, sports drinks, or powdered fruit drinks. For the lactose-intolerant, lactose-reduced milk, which contains 20 percent less lactose than the regular kind, provides a good alternative to skim or lowfat milk while delivering a comparable amount of calcium.

Calcium-rich foods need not be fattening, either. One cup of skim milk (302 milligrams calcium) has only half the calories of a cup of whole milk (291 milligrams calcium). A cup of plain lowfat yogurt (400 milligrams calcium) has fewer calories than a similar serving of lowfat fruit-flavored yogurt (314 milligrams calcium). In addition to the wide range of dairy products available in your supermarket, other calcium-rich foods—many of them low in calories—include dark green vegetables, such as broccoli, kale, and mustard and turnip greens; tofu; dried beans; and the soft bones of canned fish such as salmon and sardines.

It’s important to remember that dieting and eating a calcium-rich diet are not mutually exclusive. A study of nine- to 12-year-old girls who increased their calcium intake from 750 milligrams per day to 1,370 milligrams daily for one year by consuming more dairy foods found they developed greater total and spinal bone density than girls who did not change their diets, yet they gained no extra weight.

 

Look for Calcium in Unexpected Sources

Being good to your bones doesn’t necessarily mean eating cottage cheese every day for the rest of your life. Many prepared foods, ranging from fortified orange juice to some kinds of tortillas, contain calcium-based food additives. In fact, a wide variety of unexpected foods contain some calcium. Depending on the quantities and combinations you consume, eating a balanced diet can provide an adequate amount of calcium without restricting your choices to dairy products. For example, just one slice of calcium-fortified bread provides as much calcium as a glass of milk.

Read food labels carefully. You may be surprised at what you find. Following are some examples of the amount of calcium present in a variety of foods


Food

Serving size
Calcium
(milligrams)

Calories
Fat
(grams)

Dairy Products
Cheddar cheese 1 ounce 204 115 9
Mozzarella cheese
(part skim milk)
1 ounce 207 80 5
Cottage cheese
(lowfat 2%)
1 cup 155 200 4
Milk, Skim 1 cup 302 85
2% 1 cup 297 120 5
Whole 1 cup 291 150 8
Yogurt, Plain, lowfat 1 cup 415 145 4
Fruit-flavored, lowfat 1 cup 345 230 4
Cheese pizza
(1/8 of 15 inch pie)
1 slice 220 290 9
Macaroni & cheese 1 cup 200 230 10
Fish
Salmon, pink
(canned, with bones)
3 ounces 167 120 4.6
Sardines
(in oil, with bones)
3 medium
(3 ounces)
370 175 9
Bread and Cereal
Oatmeal
(instant, fortified)
1 packet 160 105 4
Pancakes (from mix) one 4″
pancake
30 60 2
Wheat bread (enriched) 1 slice 30 65 1
Vegetables
Broccoli, raw 1 spear 72 40 0
cooked, chopped 1cup 354 45 0
Collards, fresh, cooked, drained 1cup 357 30 0
Kale, fresh, cooked, drained 1cup 179 42 0
Other
Hot cocoa 6 oz. 90 100 1
Tofu, 1 piece
(1-1/2 x 2-3/4 x 1 inch)
100 85 5
Tomato soup
(made with milk)
1 cup 160 160 6
Pork and beans 1 cup 140 310 7
Source: “USDA Nutritive Value of Foods.” Washington, DC, Human Nutrition Information Services, U.S. Department of Agriculture, 1985; 72. Home and Garden Bulletins.

 

To keep your weight down and your bones strong, boost your calcium and hold down the calories by snacking on broccoli with lowfat cheese dip—less fattening than chips—or drinking low-fat milk instead of soft drinks. For a treat, try switching from cake or cookies to lowfat frozen yogurt or ice milk. When snacking, try sprinkling Parmesan cheese on plain popcorn. Never starve yourself to lose weight, because this can increase bone loss so severely that you can begin developing osteoporosis in your 20s. Girls and teens who try to emulate the pencil-thin waifs who populate fashion magazines are setting themselves up for a future of chronic pain.

Eating calcium-fortified foods is also a valid way of boosting your calcium intake. Since 1993, the U.S. Food and Drug Administration (FDA) has allowed food producers to claim benefits against several diseases—among them, osteoporosis. Authorized claims must meet federal standards prohibiting false or misleading labeling.

As a result, food labels now not only list the calcium content of a product but tell whether the level is high enough to reduce the risk of osteoporosis without also delivering excessive amounts of other nutrients, such as fat. For example, whole milk, though high in calcium, cannot bear a calcium-osteoporosis claim because it also delivers an excessive level of fat. Skim and lowfat milk and milk products, yogurt, tofu, and calcium-fortified citrus drinks generally qualify for the calcium-osteoporosis health claim.

Though experts strongly recommend a calcium-rich diet as the preferred source of this important mineral, supplements do provide an alternative. The calcium from most supplements can be absorbed as easily as the calcium in milk, though calcium citrate supplements may make a bit more calcium available for use by the body. Recent studies show that this type of supplement also causes less constipation than others, has fewer gastrointestinal side effects, and is less likely to cause kidney stones. Calcium carbonate is often recommended because it contains the highest percentage of absorbable calcium gluconate. Calcium-containing antacids in liquid or chewable form are a good source of calcium if you have difficulty swallowing tablets.

You don’t need to get “chelated” calcium tablets. They are costly and offer no advantage over other types of calcium. Calcium supplements containing magnesium are also unnecessary, since most people get enough magnesium in their diets. Likewise, calcium plus Vitamin D is usually unneeded. You’re likely to be getting enough Vitamin D from fortified foods, your multivitamin supplement, or exposure to sunlight. Avoid bone meal and dolomite. These “natural” supplements may be contaminated with toxic substances such as lead, mercury, and arsenic.

Calcium supplements are best absorbed in the presence of plenty of stomach acid, so it’s better to take them with meals. Absorption is also better if you take the tablets throughout the day rather than in a single dose. To make certain a supplement will be properly absorbed, check the label to see whether it meets U.S. Pharmacopoeia (USP) standards, or test a tablet by dropping it into a small glass of vinegar and stirring occasionally. If the tablet doesn’t dissolve within 30 minutes, the calcium probably won’t be absorbed by your body.

Although too much calcium is suspected to increase the risk of kidney stones, the NIH consensus panel still concluded that calcium supplementation, up to a total of 2,000 milligrams daily, appears to be safe in people who are not at risk for kidney stones or high levels of blood calcium.

 

Remodeling in Progress

Deep within the bones, an army of cells constantly tears down aging bone mass and builds it anew. Since estrogen fosters new growth, the reduced levels found in menopause can quickly lead to a reduction in bone density. Adequate supplies of calcium throughout life can alleviate the problem. After menopause, hormone replacement therapy can boost the bones’ calcium absorption, preventing osteoporosis in three-quarters of the women at risk.

 

Other Factors with Impact on Your Calcium Levels

Your body’s ability to use the calcium you consume depends on not only the total calcium content of your diet but also other dietary elements that can either boost or inhibit its absorption. For example, the absorption of calcium from some leafy green vegetables such as broccoli and kale compares favorably to the absorption of calcium from milk. (Spinach, on the other hand, is not a good source due to poor absorption.) Caffeine and salt both increase the loss of calcium through the urine; while high amounts of fiber tend to reduce calcium absorption.

Vitamin D promotes absorption of calcium from the intestines into the bloodstream. Your skin manufactures this vitamin whenever exposed to sunlight. For many people casual exposure to the sun—15 minutes to an hour per day—is enough to provide all the Vitamin D they need. It’s also commonly available in Vitamin D-fortified foods, such as milk and cold cereals.

Nevertheless, Vitamin D deficiency remains a health risk for older adults—particularly the homebound elderly and those in long-term care facilities. Because adequate levels of this important vitamin are essential for proper calcium absorption, the NIH recommends that adults get 400 to 600 IU daily. People at greater risk of a deficiency should consume up to 800 IU per day, according to the National Osteoporosis Foundation. This includes the elderly, chronically ill, housebound, and institutionalized. Be careful, though, to restrict your intake to these levels, because massive doses of vitamin D can be harmful.

Salt. The high sodium content of a vast variety of foods can play havoc with your calcium level. Sodium pulls large amounts of calcium into the kidneys, where it is subsequently lost through the urinary tract. Over the course of a decade, addition of little more than a teaspoon of salt per day to the diet of a healthy postmenopausal woman is enough to draw 7 to 8 percent of the calcium from her bones.

Protein. While it’s true that protein encourages loss of calcium through the urine, it’s also a fact that most protein-rich foods—including meat, milk, and eggs—contain high levels of phosphorus, which has the opposite effect. The net effect of such foods on your calcium balance is therefore of little concern, provided you eat them in moderate amounts and get enough calcium to begin with. In excessive amounts, however, both protein and phosphorus can have negative effects on your calcium status.

Caffeine. For many years, medical authorities believed that regular caffeine intake was associated with a loss in bone density. However, recent investigations have failed to confirm this, so if you’re a coffee drinker, your calcium requirements are no greater than normal.

Alcohol and tobacco. Smoking damages your bones and additional calcium often can’t compensate for it. Heavy smokers generally show significantly lower bone density than nonsmokers and tend to maintain a leaner body weight; women who smoke experience an earlier menopause. In fact, the increased prevalence of women smokers over the past three decades may be a contributing factor to the rise in osteoporosis-related fractures among older women today. Some experts think that excessive drinking also can trigger the development of osteoporosis and can place people in situations where they face a heightened risk of accidents or falls. To maintain adequate bone density, avoid smoking altogether and either refrain from drinking or reduce your intake of alcoholic beverages.

 

Seven Easy Ways to Defeat Osteoporosis

Get your full allowance of calcium
Cut your caffeine consumption to a maximum of 2 cups per day
Keep your protein intake reasonable (If you’re average, divide your weight by 2. The result is the number of grams of protein you need daily.)
Hold your daily intake of fiber below 30 to 35 grams
Keep your alcohol intake moderate (no more that 1 or 2 drinks daily)
Don’t smoke
Make weight-bearing exercise part of your daily routine

 

Phosphorus. Phosphorus is commonly believed to influence calcium absorption, but the jury is still out on its practical effect.

Researchers believe that phosphorus tends to suppress the urinary loss of calcium. However, too much phosphorus may accelerate loss of bone. To keep your phosphorus level in line, avoid consuming large quantities of foods labeled as containing sodium phosphate, potassium phosphate, phosphoric acid, pyrophosphate, or polyphosphate.

Soy isoflavones. Use of soy-based foods to treat “side effects” of menopause is currently all the rage. Soy products contain isoflavones—weak estrogen-like compounds often dubbed “phytoestrogens.” They’ve been found effective for reducing the risk of heart disease, and some researchers hope that they’ll stave off osteoporosis as well. At present, however, the evidence is still inconclusive.

Estrogen replacement therapy. Since estrogen is so important for maintaining bone density in women, physicians often recommend estrogen replacement therapy (ERT), or hormone replacement therapy (HRT)—a combination of estrogen and progesterone—at menopause. HRT, coupled with a high-calcium diet and moderate exercise, is an established strategy to prevent rapid loss of bone density following menopause. Its ability to improve bone density has been verified in clinical trials. It also reduces the chances of spinal column fractures by 50 to 80 percent, and the risk of other fractures by 25 percent, after 5 years of use. Better yet, it’s effective even when a woman doesn’t start taking it until after age 70.

Nevertheless, hormones are not a substitute for calcium. If you decide to begin ERT or HRT after weighing all the benefits and risks, you should continue to keep your calcium intake at recommended levels.

Other medications. Three new drugs offer alternatives to those postmenopausal women who cannot tolerate or do not wish to take estrogen replacement therapy. Alendronate (Fosamax) is prescribed for both the prevention and treatment of osteoporosis. It inhibits bone resorption and promotes bone build-up, leading to increased bone mass. Menopausal women treated with the drug for three years gained significant bone mass at the hip and spine. If your physician prescribes this drug, be sure to take it as directed, since it is poorly absorbed in the gastric system.

Raloxifene (Evista), a selective estrogen-receptor modulator, is another drug approved for use in prevention and treatment of osteoporosis. Although it yields only a slight increase in bone density, it has reduced the risk of spinal fractures by 36 to 50 percent.

Risedronate sodium (Actonel) also is approved for prevention and treatment of osteoporosis in postmenopausal women, and of steroid-induced osteoporosis in men and women. Studies have shown that the drug slows or stops bone loss, increases bone density, and lowers the risk of spinal and other fractures.

For those who have already been diagnosed with osteoporosis, physicians may opt to use calcitonin. A naturally-occurring hormone, calcitonin helps to regulate calcium absorption and bone development and slows the natural breakdown of bone. It is available in injection form (Calcimar, Miacalcin) or in a nasal spray (Miacalcin).

Exercise. Weight-bearing exercises—activities that force bones to work against gravity—are important for preventing osteoporosis. Walking, probably the most beneficial weight-bearing exercise, can help to maintain overall body strength and stability even in very elderly people. Other desirable activities for people of all ages are racquet sports, basketball, soccer, hiking, skiing, jogging, aerobic exercise, dancing, stair climbing, rollerblading, bicycling, and rowing.

Remember that the benefits of these activities last only as long as you continue them. If you are at risk of developing osteoporosis, you should make exercise an integral part of your life.

Prevention of osteoporosis requires attention to diet and lifestyle issues throughout your life. We can make sure children and grandchildren grow up with strong bones, but what about ourselves? Are we doomed to fractures because of all those glasses of milk we never drank?

No matter what your age or the present state of your bones, it’s never too late to slow the process of osteoporosis or reduce the possibility of broken bones. Don’t look back; look ahead. Start now to eat a balanced diet that includes adequate amounts of calcium and no more than moderate levels of salt and caffeine. Encourage other family members—from toddlers to grandparents—to do the same. Exercise regularly, and reduce or eliminate your smoking and alcohol use. Then take advantage of the opportunity to use your strong, healthy bones for life.

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