Protecting Your Bones
Physicians Committee for Responsible Medicine
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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. In fact, in a
12-year Harvard study of 78,000 women, those who drank milk three times a day actually
broke more bones than women who rarely drank milk.1 Similarly, a 1994
study of elderly men and women in Sydney, Australia, showed that higher dairy product
consumption was associated with increased fracture risk. Those with the highest
dairy product consumption had approximately double the risk of hip fracture compared to
those with the lowest consumption.2
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
1. Get calcium from greens, beans, or fortified foods.
The most healthful calcium sources are green leafy
vegetables and legumes, or "greens and beans" for short. Broccoli, Brussels
sprouts, collards, kale, mustard greens, Swiss chard, and other greens are loaded with
highly absorbable calcium and a host of other healthful nutrients. The exception is
spinach, which contains a large amount of calcium but tends to hold onto it very
tenaciously, so that you will absorb less of it.
Beans are humble foods, and you might not know that they
are loaded with calcium. There is more than 100 milligrams of calcium in a plate of baked
beans. If you prefer chickpeas, tofu, or other bean or bean products, you will find plenty
of calcium there, as well. These foods also contain magnesium, which your body uses along
with calcium to build bones.
If you are looking for a very concentrated calcium source,
calcium-fortified orange or apple juices contain 300 milligrams or more of calcium per cup
in a highly absorbable form. Many people prefer calcium supplements, which are now widely
available.
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.
2. Exercise, so calcium has somewhere to go.
Exercise is important for many reasons, including
keeping bones strong. Active people tend to keep calcium in their bones, while Sedentary
people lose calcium.
3. Get vitamin D from the sun, or supplements if you
need them.
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 little or no sun exposure, you can get vitamin D from any multiple vitamin. The
Recommended Dietary Allowance is 200 IU (5 micrograms) per day. Vitamin D is often added
to milk, but the amount added is not always well controlled.
How to Keep It There
It's not enough to get calcium into your bones. What is
really critical is keeping it there. Here's how:
1. Reduce calcium losses by avoiding excess salt.
Calcium in bones tends to dissolve into the bloodstream,
then pass through the kidneys into the urine. Sodium (salt) in the foods you eat can
greatly increase calcium loss through the kidneys.3 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.
2. Get your protein from plants, not animal products.
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.4
3. 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 a fracture.5
American recommendations for calcium intake are high,
partly because the meat, salt, tobacco, and physical inactivity of American life leads to
overly rapid and unnatural loss of calcium through the kidneys. By controlling these basic
factors, you can have an enormous influence on whether calcium stays in your bones or
drains out of your body.
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.
Many women find these hormones distasteful because the most
commonly prescribed brand, Premarin, is made from pregnant mares' urine, as its name
suggests. What has many physicians worried is the fact that estrogens increase the risk of
breast cancer. The Harvard Nurses' Health Study found that women taking estrogens have 30
to 80 percent more breast cancer, compared to other women.6
Moreover, Premarin may aggravate heart problems. In a study
of 2,763 postmenopausal women with coronary disease followed for an average of four years,
there were as many heart attacks and related deaths in women treated with the combined
regimen of estrogens and a progesterone derivative, as with placebo, but the coronary
problems occurred sooner in women taking hormones. Hormone-treated women were also more
likely to develop dangerous blood clots and gallbladder disease.7 Controlling
calcium losses is a much safer strategy.
Reversing Osteoporosis
If you already have osteoporosis, you will want to speak
with your doctor about exercises 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:8
- 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 minimize 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.
- A lower than normal amount of testosterone
can encourage
osteoporosis. About 40 percent of men over 70 years of age have decreased levels of
testosterone.
In many of the remaining cases, the causes are excessive
calcium losses and inadequate vitamin D. The first part of the solution is to avoid animal
protein, excess salt and caffeine, and tobacco, and to stay physically active in order to
reduce calcium losses. Second, take vitamin D supplements as prescribed by your physician.
The usual amount is 200 IU (5 micrograms) per day, but it may be doubled if you get no sun
exposure at all. If you have trouble absorbing calcium due to reduced stomach acid, your
doctor can recommend hydrochloric acid supplements.
| Calcium and Magnesium in Foods (milligrams) |
| Food Source |
Calcium |
Magnesium |
| Collards (1 cup,
boiled) |
358 |
52 |
| Orange juice,
calcium-fortified (1 cup) |
350* |
-- |
| Oatmeal, instant
(2 packets) |
326 |
70 |
| Figs, dried (10
medium) |
269 |
111 |
| Tofu, calcium-set
(1/2 cup) |
258 |
118 |
| Spinach (1 cup,
boiled) |
244 |
158 |
| Soybeans (1 cup,
boiled) |
175 |
148 |
| White beans (1
cup, boiled) |
161 |
113 |
| Mustard greens (1
cup, boiled) |
150 |
20 |
| Navy beans (1 cup,
boiled) |
128 |
107 |
| Vegetarian baked
beans (1 cup) |
128 |
82 |
| Great northern
beans (1 cup, boiled) |
121 |
88 |
| Black turtle beans
(1 cup, boiled) |
103 |
91 |
| Swiss chard (1
cup, boiled) |
102 |
152 |
| Broccoli (1 cup,
boiled) |
94 |
38 |
| Kale (1 cup
boiled) |
94 |
24 |
| English muffin |
92 |
11 |
| Butternut squash
(1 cup, boiled) |
84 |
60 |
| Pinto beans (1
cup, boiled) |
82 |
95 |
| Chick peas (1 cup,
canned) |
80 |
78 |
| Sweet potato (1
cup, boiled) |
70 |
32 |
| Green beans (1
cup, boiled) |
58 |
32 |
| Barley (1 cup) |
57 |
158 |
| Brussels sprouts
(8 sprouts) |
56 |
32 |
| Navel orange (1
medium) |
56 |
15 |
| Raisins (2/3 cup) |
53 |
35 |
| Source: J.A.T. Pennington, Bowes and Church's
Food Values of Portions Commonly Used. (Philadelphia: J.B. Lippincott, 1994.) |
| *Information from manufacturer |
References
1. Feskanich D, Willett WC, Stampfer MJ, Colditz GA. Milk, dietary calcium, and bone
fractures in women: a 12-year prospective study. Am J Publ Health 1997;87:992-7.
2. Cumming RG, Klineberg RJ. Case-control study of risk factors for hip fractures in the
elderly. Am J Epidemiol 1994;139:493-503.
3. Nordin BEC, Need AG, Morris HA, Horowitz M. The nature and significance of the
relationship between urinary sodium and urinary calcium in women. J Nutr 1993;123:1615-22.
4. Remer T, Manz F. Estimation of the renal net acid excretion by adults consuming diets
containing variable amounts of protein. Am J Clin Nutr 1994;59:1356-61.
5. Hopper JL, Seeman E. The bone density of female twins discordant for tobacco use. N
Engl J Med 1994;330:387-92.
6. Colditz GA, Stampfer MJ, Willett WC, et al. Type of postmenopausal hormone use and risk
of breast cancer: 12-year follow-up from the Nurses' Health Study. Cancer Causes and
Control 1992;3:433-9.
7. Hulley S, Grady D, Bush T, et al. Randomized trial of estrogen plus progestin for
secondary prevention of coronary heart disease in postmenopausal women. JAMA
1998;280:605-13.
8. Peris P, Guanabens N, Monegal A, et al. Aetiology and presenting symptoms in male
osteoporosis. Br J Rheumatol 1995;34:936-41.
Source:
http://www.strongbones.org/
Update : 01-12-2001
