Osteoporosis

Studies attempting to uncover the effects of high animal protein intake on the risk of osteoporosis have produced confusing and contradictory results.1 2 3 4 5 The same is true of studies attempting to find out whether vegetarians are protected against osteoporosis.6 7 8 9 10 11 12 13 Moreover, while some studies report that protein supplementation lowers death rates and shortens hospital stays14 or reduces bone loss among people with osteoporosis,15 others have found that such supplementation is of little value.16

These conflicting findings may occur in part because dietary protein produces opposing effects on bone. On one hand, dietary protein increases the loss of calcium in urine,17 18 which should increase the risk of osteoporosis. On the other hand, normal bone formation requires adequate dietary protein, and low dietary protein intake has been associated with low bone mineral density.19 Current research shows that finding the line between too much protein and too little protein remains elusive, though extremes in protein intake - either high or low - might possibly increase the risk of osteoporosis.

Short-term increases in dietary salt result in increased urinary calcium loss, which suggests that over time, salt intake may cause bone loss.20 Increasing dietary salt has increased markers of bone loss in postmenopausal (though not premenopausal) women.21 22 23 Although a definitive link between salt intake and osteoporosis has not yet been proven, many doctors recommend that people wishing to protect themselves against bone loss use less salt and eat fewer processed and restaurant foods, which tend to be highly salted.

Like salt, caffeine increases urinary loss of calcium.24 Caffeine intake has been linked to increased risk of hip fractures25 and to a lower bone mass in women who consumed inadequate calcium.26 Many doctors recommend decreasing caffeinated coffee, black tea, and caffeine-containing soft drinks as a way to improve bone mass.

Curiously, while caffeine-containing tea consumption has been linked to osteoporosis in some studies,27 others have reported that tea drinkers have a lower risk of osteoporosis than do people who do not drink tea.28 29 Possibly, the calcium-losing effect of caffeine in tea is overridden by other constituents of tea, such as flavonoids.

People who consume soft drinks have been reported to have an increased incidence of bone fractures,30 although short-term consumption of carbonated beverages has not affected markers of bone health.31 The problem, if one exists, may be linked to phosphoric acid, a substance found in many soft drinks. In one trial, children consuming at least six glasses of soft drinks containing phosphoric acid had more than five times the risk of developing low blood levels of calcium compared with other children.32 Although a few studies have not linked soft drinks to bone loss,33 the preponderance of evidence now suggests that a problem may exist.

Soy foods such as tofu, soy milk, roasted soy beans, and soy protein powders may be beneficial in preventing osteoporosis. Isoflavones from soy have protected against bone loss in animal studies.34 In a double-blind trial, postmenopausal women who supplemented with 40 grams of soy protein powder (containing 90 mg of isoflavones) per day were protected against bone mineral loss in the spine, although lower amounts were not protective.35 Although the use of soy in the prevention of osteoporosis looks hopeful, no long-term human studies have examined the effects of soy or soy-derived isoflavones on bone density or fracture risk.

The effect of dairy products on the risk of osteoporosis-related fractures is subject to controversy. According to a review of 46 studies,36 different dairy products appear to have different effects on bone density and fracture rates. Milk, especially nonfat milk, probably does more good than harm because of its relatively lower protein and salt content, as well as its higher level of calcium. Cottage cheese and American cheese, on the other hand, probably do more harm than good. Cottage cheese is high in protein and salt but low in calcium, factors which could contribute to bone loss. American cheese is extremely high in salt and high in protein. These foods are not recommended as calcium sources for the prevention of osteoporotic fractures. Although there may be better ways of getting calcium, younger women who wish to prevent osteoporosis might consider nonfat milk and nonfat yogurt to be reasonable dietary calcium sources.

Exercise is known to help protect against bone loss.38 The more weight-bearing exercise done by men and postmenopausal women, the greater their bone mass and the lower their risk of osteoporosis. Walking is a perfect weight-bearing exercise. For premenopausal women, exercise is also important, but taken to extreme, it may lead to cessation of the menstrual cycle, which contributes to osteoporosis.39

Researchers has demonstrated that excess body mass helps protect against osteoporosis. As a result, researchers have been able to show that people who successfully lose weight have greater bone loss compared with those who do not lose weight.40 Therefore, people who lose weight need to be particularly vigilant about preventing osteoporotic fractures.

However, of course, excess weight contributes to many other health problems - cardiovascular, joint, muscle and tendon health, respiratory system, diabetes, etc. So the important point here is that those who embark on intensive weight loss programs need to be careful to also monitor their bone mass.

Although insufficient when used as the only intervention, calcium supplements help prevent osteoporosis.41 Though some of the research remains controversial, the protective effect of calcium on bone mass is one of very few health claims permitted on supplement labels by the U.S. Food and Drug Administration.

In some studies, higher calcium intake has not correlated with a reduced risk of osteoporosis - for example, in women shortly after becoming menopausal42 or in men.43 However, after about three years of menopause, calcium supplementation does appear to take on a protective effect for women.44 Even the most positive trials using isolated calcium supplementation show only minor effects on bone mass. Nonetheless, a review of the research shows that calcium supplementation plus hormone replacement therapy is much more effective than hormone replacement therapy without calcium.45 Double-blind research has found that increasing calcium intake results in greater bone mass in girls.46 An analysis of many trials investigating the effects of calcium supplementation in premenopausal women has also shown a significant positive effect.47 Most doctors recommend calcium supplementation as a way to partially reduce the risk of osteoporosis and to help people already diagnosed with the condition. In order to achieve the 1,500 mg per day calcium intake many researchers deem optimal, 800 to 1,000 mg of supplemental calcium are generally added to the 500 to 700 mg readily obtainable from the diet.

Ipriflavone is a synthetic flavonoid derived from the soy isoflavone, daidzein. It promotes the incorporation of calcium into bone and inhibits bone breakdown, thus preventing and reversing osteoporosis. Many clinical trials, including numerous double-blind trials, have consistently shown that long-term treatment with 600 mg of ipriflavone per day, along with 1,000 mg supplemental calcium, is both safe and effective in halting bone loss in postmenopausal women, or in women who have had their ovaries removed. Ipriflavone has also been found to improve bone density in established cases of osteoporosis in most48 49 50 51 52 53 54 55 56 57 58 but not all59 clinical trials. Ipriflavone therapy not only stops bone loss, it also actually increases bone density and significantly reduces the number of vertebral fractures and amount of bone pain.

Vitamin D increases calcium absorption, and blood levels of vitamin D are directly related to the strength of bones.60 Mild deficiency of vitamin D is common in the fit, active elderly population and leads to an acceleration of age-related loss of bone mass and an increased risk of fracture.61 In double-blind research, vitamin D supplementation has reduced bone loss in women who consume insufficient vitamin D from food62 and slowed bone loss in people with osteoporosis.63 However, the effect of vitamin D supplementation on osteoporosis risk remains surprisingly unclear,64 65 with some trials reporting little if any benefit.66 Moreover, trials reporting reduced risk of fracture have usually combined vitamin D with calcium supplementation,67 making it difficult to assess how much benefit is caused by supplementation with vitamin D alone.68 Impaired balance and increased body sway are important causes of falls in elderly people with osteoporosis.69 Vitamin D works with calcium to prevent some musculoskeletal causes of falls. In a double-blind trial, elderly women who were given 800 IU per day of vitamin D and 1,200 mg per day of calcium had a significantly lower rate of falls and subsequent fractures than did women given the same amount of calcium alone.70

Despite inconsistency in the research, many doctors recommend 400 to 800 IU per day of supplemental vitamin D, depending upon dietary intake and exposure to sunlight.

A preliminary trial found that elderly women with osteoporosis who were given 4 grams of fish oil per day for four months had improved calcium absorption and evidence of new bone formation.71 Fish oil combined with evening primrose oil (EPO) may confer added benefits. In a controlled trial, women received 6 grams of a combination of EPO and fish oil, or a matching placebo, plus 600 mg of calcium per day for three years.72 The EPO/fish oil group experienced no spinal bone loss in the first 18 months and a significant 3.1% increase in spinal bone mineral density during the last 18 months.

Vitamin K is needed for bone formation. People with osteoporosis have been reported to have low blood levels73 74 and low dietary intake of vitamin K.75 76 One study found that postmenopausal (though not premenopausal) women may reduce urinary loss of calcium by taking 1 mg of vitamin K per day.77 People with osteoporosis given large amounts of vitamin K2 (45 mg per day) have shown an increase in bone density after six months78 and decreased bone loss after one79 or two80 years.

Other preliminary studies have reported that vitamin K supplementation increases bone formation in some women81 and that higher vitamin K intake correlates with greater bone mineral density.82 Some doctors recommend 1 mg vitamin K1 to postmenopausal women as a way to help maintain bone mass, though optimal intake remains unknown.

In a preliminary study, people with osteoporosis were reported to be at high risk for magnesium malabsorption.83 Both bone84 and blood85 levels of magnesium have been reported to be low in people with osteoporosis. Supplemental magnesium has reduced markers of bone loss in men.86 Supplementing with 250 mg up to 750 mg per day of magnesium arrested bone loss or increased bone mass in 87% of people with osteoporosis in a two-year, controlled trial.87 Some doctors recommend that people with osteoporosis supplement with 350 mg of magnesium per day.

One trial studying postmenopausal women combined hormone replacement therapy with magnesium (600 mg per day), calcium (500 mg per day), vitamin C, B vitamins, vitamin D, zinc, copper, manganese, boron, and other nutrients for an eight- to nine- month period.88 In addition, participants were told to avoid processed foods, limit protein intake, emphasize vegetable over animal protein, and limit consumption of salt, sugar, alcohol, coffee, tea, chocolate, and tobacco. Bone density increased a remarkable 11%, compared to only 0.7% in women receiving hormone replacement alone.

Levels of zinc in both blood and bone have been reported to be low in people with osteoporosis,89 and urinary loss of zinc has been reported to be high.90 In one trial, men consuming only 10 mg of zinc per day from food had almost twice the risk of osteoporotic fractures compared with those eating significantly higher levels of zinc in their diets.91 Whether zinc supplementation protects against bone loss has not yet been proven, though in one trial, supplementation with several minerals including zinc and calcium was more effective than calcium by itself.92 Many doctors recommend that people with osteoporosis, as well as those trying to protect themselves from this disease, supplement with 10 to 30 mg of zinc per day.

Copper is needed for normal bone synthesis. Recently, a two-year, controlled trial reported that 3 mg of copper per day reduced bone loss.93 When taken over a shorter period of time (six weeks), the same level of copper supplementation had no effect on biochemical markers of bone loss.94 Some doctors recommend 2 to 3 mg of copper per day, particularly if zinc is also being taken, in order to prevent a deficiency. Supplemental zinc significantly depletes copper stores, so people taking zinc supplements for more than a few weeks generally need to supplement with copper also. All minerals discussed so far - calcium, magnesium, zinc, and copper - are sometimes found at appropriate levels in high-potency multivitamin-mineral supplements.

Boron supplementation has been reported to reduce urinary loss of calcium and magnesium in some,95 but not all,96 preliminary research. However, those who are already supplementing with magnesium appear to achieve no additional calcium-sparing benefit when boron is added.97 Finally, in the original report claiming that boron reduced loss of calcium,98 the effect was achieved by significantly increasing estrogen and testosterone levels, hormones that have been linked to cancer risks. Therefore, it makes sense for people with osteoporosis to supplement with magnesium instead of, rather than in addition to, boron.

Interest in the effect of manganese and bone health began when famed basketball player Bill Walton's repeated fractures were halted with manganese supplementation.99 A subsequent, unpublished study reported manganese deficiency in a small group of osteoporotic women.100 Since then, a combination of minerals including manganese was reported to halt bone loss.101 However, no human trial has investigated the effect of manganese supplementation alone on bone mass. Nonetheless, some doctors recommend 10 to 20 mg of manganese per day to people concerned with maintenance of bone mass.

Silicon is required in trace amounts for normal bone formation,102 and supplementation with silicon has increased bone formation in animals.103 In preliminary human research, supplementation with silicon increased bone mineral density in a small group of people with osteoporosis.104 Optimal supplemental levels remain unknown, though some multivitamin-mineral supplements now contain small amounts of this trace mineral.

Strontium may play a role in bone formation, and preliminary evidence suggests that women with osteoporosis may have reduced absorption of strontium.105 The first medical use of strontium was described in 1884. (Strontium supplements do not contain the radioactive form of strontium that is a component of nuclear fallout.) Years ago in a preliminary trial, people with osteoporosis were given 1.7 grams of strontium for a period of time ranging between three months and three years; afterward, they reported a significant reduction in bone pain, and there was evidence suggesting their bone mass had increased.106 Strontium preparations, providing 200 to 400 mg per day, were used for decades during the first half of the twentieth century without any apparent toxicity.107 Strontium supplementation may inhibit bone breakdown by protecting vulnerable bone surfaces.

Increased bone formation and decreased bone pain were also reported in six people with osteoporosis given 600 to 700 mg of stable strontium per day.108 Although levels used in these preliminary studies have been very high, optimal intake remains unknown. Some doctors recommend only 1 to 3 mg per day - less than many people currently consume from their diets, but an amount that has begun to appear in some mineral formulas geared toward bone health.

Folic acid, vitamin B6, and vitamin B12 are known to reduce blood levels of homocysteine in the body, and homocysteinuria, a condition associated with high homocysteine levels, frequently causes osteoporosis. Although some healthcare practitioners have suggested these vitamins might help prevent osteoporosis by lowering homocysteine,109 no research has explored this relationship. For the purpose of lowering homocysteine, amounts of folic acid and vitamins B6 and B12 found in high-potency B-complex supplements and multivitamins should be adequate.

Preliminary evidence suggests that progesterone might, in theory, reduce the risk of osteoporosis.110 A preliminary trial using topically applied natural progesterone cream in combination with dietary changes, exercise, vitamin and calcium supplementation, and estrogen therapy, reported large gains in bone density over a three-year period in a small group of postmenopausal women, but no comparison was made to examine the effect of using the same protocol without progesterone.111 Other trials have reported that adding natural progesterone to estrogen therapy did not improve the bone-sparing effects of estrogen when taken alone112 and that progesterone applied topically every day for a year did not reduce bone loss.113 In a preliminary trial, bone mineral density increased among healthy elderly women and men who were given 50 mg per day of DHEA as a supplement.114 It is not known if supplementation would have similar effects in people with established osteoporosis.

Horsetail is a rich source of silicon, and preliminary research suggests that this trace mineral may help maintain bone mass. Effects of horsetail supplementation on bone mass have not been studied.

Black cohosh has been shown to improve bone mineral density in animals fed a low calcium diet,115 but it has not been studied for this purpose in humans.