Many factors are known or suspected to accelerate the rate of bone loss. These include smoking, alcohol, low calcium intake, lack of exercise, various medications, and several medical illnesses. Excessive consumption of vitamin Amay also increase risk of osteoporosis,1,109and rapid weight loss may increase the risk in postmenopausal women.2Raw food vegetarians are also likely to have significant bone thinning.129

In general, women are far more prone to osteoporosis than men. For this reason, the following discussion focuses almost entirely on women.

Hormone replacement therapy prevents or reverses osteoporosis in women. However, now that long-term use of hormone replacement therapy has been found to be unsafe, conventional medical treatment for osteoporosis in women centers mainly on drugs in the bisphosphonate family, such as Fosamax (taken along with calcium and vitamin D— see below).

Exercise, especially weight-bearing exercise, almost certainly helps strengthen bone (although the evidence for this apparently obvious statement is weaker than one might expect).167-170Minimal evidence suggests that the Chinese form of exercise called Tai Chi may also provide some benefit.177,180However, in a randomized trial of 86 postmenopausal women with osteopenia (low bone density), tai chi plus usual care did not appear to improve bone mineral density of proximal femur or lumbar spine compared to usual care alone.195

There is good evidence that people with osteoporosis, or who are at risk for it, should take calcium and vitamin D supplements regardless of what other treatments they may be using.

Substances called isoflavones found in soy and other plants may be helpful for osteoporosis (as well as general menopausal symptoms). Vitamin K and a new supplement called strontium ranelate have also shown promise. A semisynthetic isoflavone called ipriflavone has shown considerable promise for osteoporosis, but safety concerns have decreased its popularity.

Calcium and Vitamin D

Calcium is necessary to build and maintain bone. You need vitamin D, too, as the body cannot absorb calcium without it. Many people do not get enough calcium in their daily diet. Although your body can manufacture vitamin D when exposed to the sun, supplemental vitamin D may be necessary in this age of sunblock.

According to most, but not all studies, calcium supplements (especially as calcium citrate, and taken with vitamin D) appear to be modestly helpful in slowing down bone loss in postmenopausal women.3-7,121,130-131,140,165,171Contrary to some reports, milk does appear to be a useful source of calcium for this purpose.175-176Any improvements in bone density rapidly disappear once the supplements are stopped.10People who religiously continue calcium use may do better than those who forget from time to time.140Vitamin D without calcium, however, does not appear to offer more than minimal bone-protective benefits for seniors.110,181,182

The effect of calcium and vitamin D supplementation in any form is relatively minor and may not be strong enough to reduce the rate of osteoporotic fractures. A large randomized trial of over 3,000 postmenopausal women aged 65-71 years found that three years of daily supplementation with calcium and vitamin D was not associated with a significant reduction in the incidence of fractures.193

In a much larger observational study (not a randomized trial) involving 61,433 women aged 39-73, researchers investigated the effects of dietary calcium (as opposed to supplements) on the risk of osteoporosis and fracture over a 19-year period.194 They found that women who consumed less than 750 mg/day of calcium had a higher rate of osteoporotic fractures in any location. Unexpectedly, however, the study also found that those who consumed the highest amounts of calcium (over 1,137 mg/day) did not have a comparatively reduced rate of fractures or osteoporosis. Indeed, this high dietary intake was associated with an increase in the number of hip fractures for reasons the authors could not completely explain.

Use of calcium supplements early in life might put calcium "in the bank" and prevent problems later, especially when children also engage in physical exercise; however, study results are somewhat contradictory.132-136,142-145

One study found benefits for male seniors using a calcium and vitamin D-fortified milk product.141 However, there are some concerns that excessive calcium intake could raise the risk of prostate cancer in men. See the Calcium article for more information.

Vitamin D and calcium taken together may also have a modestly protective effect against the severe bone loss caused by corticosteroiddrugs such as prednisone.8,9

Certain other supplements may enhance the effects of calcium and vitamin D. One study found that adding various trace minerals ( zinc at 15 mg, copper at 2.5 mg, and manganeseat 5 mg) produced further improvement.11,12However, copper by itself may not be helpful.99

There is some evidence that essential fatty acids may also enhance the effectiveness of calcium. In one study, 65 postmenopausal women were given calcium along with either placebo or a combination of omega-6 fatty acids (from evening primrose oil) and omega-3 fatty acids (from fish oil) for a period of 18 months. At the end of the study period, the group receiving essential fatty acids had higher bone density and fewer fractures than the placebo group.13In contrast to this, however, a similar 12-month, double-blind trial of 42 postmenopausal women found no benefit from essential fatty acids.14 The explanation for the discrepancy may lie in the differences between the women studied. The first study involved women living in nursing homes, while the second studied healthier women living on their own. The second group of women may have been better nourished and already receiving sufficient essential fatty acids in their diet.

Finally, vitamin K may also enhance the effect of calcium ( see below).

Interestingly, vitamin D may offer another benefit for osteoporosis in seniors: most, though not all, studies have found that vitamin D supplementation improves balance in seniors (especially female seniors) and reduces risk of falling.103,104,112,113,120,122.123,146-149,163 Since the most common adverse consequence of osteoporosis is a fracture due to a fall, this could offer a meaningful benefit.

There is weak, preliminary evidence that calcium supplementation in healthy, postmenopausal women may slightly increase the risk of cardiovascular events, such as myocardial infarction.190

For more information, including dosage and safety issues, see the full articles on Calcium and Vitamin D.

Genistein and Other Isoflavones

Soy contains substances called isoflavones that produce effects in the body somewhat similar to the effects of estrogen. (For this reason, they are called “phytoestrogens.”) Although study results are not entirely consistent, growing evidence suggests that genisteinand other isoflavones can (like estrogen) help prevent bone loss.37-48,105,106,114,124-126,150-151,185

For example, in a 1-year, double-blind, placebo-controlled study, 90 women aged 47 to 57 were given genistein at a dose of 54 mg/day, standard hormone replacement therapy (HRT), or placebo.106The results showed that genistein prevented bone loss in the back and hip to approximately the same extent as HRT. No adverse effects on the uterus or breast were seen. A subsequent 2-year, double-blind study of 389 postmenopausal women with mild bone loss found that 54 mg of genistein plus calcium and vitamin D improved bone density to a greater extent than calcium and vitamin D alone.185 However, a fairly high percentage of participants given genistein experienced substantial digestive distress.

In a 1-year, double-blind, placebo-controlled study of 203 postmenopausal Chinese women, use of soy isoflavones at a dose of 80 mg daily had mildly positive protective effects on bone mass in the hip.125 This supplement contained 46.4% daidzein, 38.8% glycetein, and 14.7% genistein.

Another study evaluated an isoflavone supplement made from red clover(containing 6 mg biochanin A, 16 mg formononetin, 1 mg genistein, and 0.5 mg daidzein daily).126In this 1-year, double-blind, placebo-controlled study of 205 people, use of red clover isoflavones significantly reduced loss of bone in the lumbar spine. Benefits were also seen in a 1-year, double-blind, placebo-controlled study using an extract made from the soy product tofu.127

However, it is not clear that the consumption of foods rich in isoflavones offers the same benefits. For example, in placebo-controlled study involving 237 healthy women in the early stages of menopause, the consumption of isoflavone-enriched foods (providing an average of 110 mg isoflavone daily) for one year had no affect on bone density or metabolism.192

Interestingly, the effect of isoflavones on bone may be more complex than that of estrogen. Bone is always undergoing two opposite processes at once: bone breakdown and bone formation. Estrogen acts on the first of these processes: it inhibits bone breakdown. Isoflavones may affect both sides of the equation at once: inhibiting bone breakdown while at the same time enhancing new bone formation.49,50,106,126,178

In about one out of three people, intestinal bacteria convert some soy isoflavones into a substance called "equol." Isoflavones may have a greater bone-protecting effect in such "equol producers."152,183

For more information, including dosage and safety issues, see the full Soy article.

Strontium

Growing evidence indicates that the mineral strontium (as strontium ranelate) is effective as an aid in the treatment of osteoporosis.115-117,137,138

The best and largest study on strontium was a double-blind, placebo-controlled study of 1,649 postmenopausal women with osteoporosis.128 In this 3-year study, a dose of strontium ranelate at 2 g daily significantly increased bone density in the spine and hip, and significantly decreased the rate of vertebral fractures.

While some treatments for osteoporosis act to increase bone formation, and others decrease bone breakdown, some evidence suggests that strontium ranelate has a dual effect, providing both these benefits at once.153

There is one major caveat, however. At present, all major controlled clinical trials of strontium ranelate have involved some of the same researchers. Entirely independent confirmation is needed. It is not clear to what extent the “ranelate” portion of strontium ranelate is necessary for this benefit, or whether other strontium salts would work as well.

Note: The strontium used in these studies is not the same as the radioactive strontium that was such a concern during the decades of above-ground atomic testing.

For more information, including dosage and safety issues, see the full Strontium article.

Vitamin K

Increasing, but inconsistent, evidence indicates that vitamin Kmay help prevent osteoporosis.51-60,111,154, 173-174It may work by reducing bone breakdown, rather than by enhancing bone formation.155

Perhaps the best evidence for a beneficial effect comes from a 3-year, double-blind, placebo-controlled trial of 181 women.111 Participants, postmenopausal women between the ages of 50 and 60, were divided into three groups: placebo, calcium plus vitamin D plus magnesium, or calcium plus vitamin D plus magnesium plus vitamin K (at a dose of 1 g daily). Researchers monitored bone loss by using a standard DEXA bone density scan. The results showed that the study participants using vitamin K along with the other nutrients lost less bone than those in the other two groups.

However, another placebo-controlled trial involving 452 older men and woman with normal levels of calcium and vitamin D failed to demonstrate any beneficial effects of 500 mcg per day of vitamin K supplementation on bone health over a 3-year period.191

For more information, see the full Vitamin K article.

Ipriflavone

Ipriflavone is a semisynthetic variation of soy isoflavones. Ipriflavone appears to help prevent osteoporosis by interfering with bone breakdown. Estrogen works in much the same way, but ipriflavone does not appear to produce estrogenic effects anywhere else in the body other than in bone. For this reason, it probably does not increase the risk of breast or uterine cancer. However, it also does not reduce the hot flashes, night sweats, mood changes, or vaginal dryness of menopause. In addition, it may cause health risks of its own.

Numerous double-blind, placebo-controlled studies involving a total of more than 1,700 participants have examined the effects of ipriflavone on various forms of osteoporosis.15-26 Overall, it appears that ipriflavone can stop the progression of osteoporosis and perhaps reverse it to some extent.

For example, a 2-year, double-blind study followed 198 postmenopausal women who had evidence of bone loss.27 At the end of the study, there was a gain in bone density of 1% in the ipriflavone group compared to a loss of 0.7% in the placebo group.

Conversely, the largest and longest study of ipriflavone found no benefit.28 In this 3-year trial of 474 postmenopausal women, no differences in extent of osteoporosis were seen between ipriflavone and placebo groups. However, for reasons that are not clear, the researchers in this study gave women only 500 mg of calcium daily. All other major studies of ipriflavone gave participants 1,000 mg of calcium daily. It is possible that ipriflavone requires the higher dose of calcium to work properly.

Ipriflavone may also be helpful for preventing osteoporosis in women who are taking Lupron or corticosteroids, medications that accelerate bone loss.29-31 (However, the combined use of ipriflavone and drugs that suppress the immune system, such as corticosteroids, presents risks.)

There is some evidence that combining ipriflavone with estrogen may improve anti-osteoporosis benefits.32,33 However, we do not know whether such combinations increase or decrease the other benefits and adverse effects of estrogen-replacement therapy.

Finally, for reasons that are not at all clear, ipriflavone appears to be able to reduce pain in osteoporosis-related fractures that have already occurred.34-36

For more information, including dosage and safety issues, see the full Ipriflavone article.