Caution: Calcium supplements should be avoided by prostate cancer patients.

Although insufficient when used as the only intervention, calcium supplements help prevent osteoporosis.¹ 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 menopausal² or in men.³ However, after about three years of menopause, calcium supplementation does appear to take on a protective effect for women.⁴ 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.⁵ Double-blind research has found that increasing calcium intake results in greater bone mass in girls.⁶ An analysis of many trials investigating the effects of calcium supplementation in premenopausal women has also shown a significant positive effect.⁷ 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.

While phosphorus is essential for bone formation, most people do not require phosphorus supplementation, because the typical western diet provides ample or even excessive amounts of phosphorus. One study, however, has shown that taking calcium can interfere with the absorption of phosphorus, potentially leading to phosphorus deficiency in elderly people, whose diets may contain less phosphorus.⁸. The authors of this study recommend that, for elderly people, at least some of the supplemental calcium be taken in the form of tricalcium phosphate or some other phosphorus-containing preparation.

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.⁹ 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.

Vitamin D increases calcium absorption, and blood levels of vitamin D are directly related to the strength of bones.¹⁷ 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.¹⁸ In double-blind research, vitamin D supplementation has reduced bone loss in women who consume insufficient vitamin D from food and slowed bone loss in people with osteoporosis^19,20 and in postmenopausal women.²¹ However, the effect of vitamin D supplementation on osteoporosis risk remains surprisingly unclear,^22,23 with some trials reporting little if any benefit.²⁴ Moreover, trials reporting reduced risk of fracture have usually combined vitamin D with calcium supplementation,²⁵ making it difficult to assess how much benefit is caused by supplementation with vitamin D alone.²⁶

Impaired balance and increased body sway are important causes of falls in elderly people with osteoporosis.²⁷ Vitamin D works with calcium to prevent some musculoskeletal causes of falls.²⁸ 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.²⁹ Vitamin D in the amount of 800 IU per day effectively prevented falls in a double-blind study of elderly nursing home residents, but lower amounts were ineffective.³⁰

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.

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.³¹ 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.

Copper is needed for normal bone synthesis. Recently, a two-year, controlled trial reported that 3 mg of copper per day reduced bone loss.³² 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.³³ 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. Calcium, magnesium, zinc, and copper are sometimes found at appropriate levels in high-potency multivitamin-mineral supplements.

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.³⁴ 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.

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.³⁹ 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.⁴⁰ 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.

Ipriflavone is a synthetic flavonoid derived from the soy isoflavone called 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 some,^{41,42,43,44,45,46,47,48,49,50,51} but not all,⁵² clinical trials.

However, one double-blind study has failed to confirm the beneficial effect of ipriflavone. In that study, ipriflavone was no more effective than a placebo for preventing bone loss in postmenopausal women with osteoporosis.⁵² The women in this negative study were older (average age, 63.3 years) than those in most other ipriflavone studies and had relatively severe osteoporosis. It is possible that ipriflavone works only in younger women or in those with less severe osteoporosis.

In a preliminary study, people with osteoporosis were reported to be at high risk for magnesium malabsorption.⁵³ Both bone⁵⁴ and blood⁵⁵ levels of magnesium have been reported to be low in people with osteoporosis. Supplemental magnesium has reduced markers of bone loss in men.⁵⁶ 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, preliminary trial.⁵⁷ Supplementing with magnesium (150 mg per day for one year) also increased bone mass in pre-adolescent and adolescent girls in a double-blind study.⁵⁸ 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.⁵⁹ 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.

Vitamin K is needed for bone formation. People with osteoporosis have been reported to have low blood levels^67,68 and low dietary intake of vitamin K.^69,70 One study found that postmenopausal (though not premenopausal) women may reduce urinary loss of calcium by taking 1 mg of vitamin K1 per day.⁷¹ People with osteoporosis given large amounts of vitamin K2 in the form of menaquinine-4 (45 mg per day) have shown an increase in bone density after six months⁷² and decreased bone loss after one⁷³ or two⁷⁴ years. Supplementation with vitamin K2 in the form of menaquinone-7 (180-375 mcg per day) has been reported to improve bone quality and to slow both bone loss and the loss of vertebral height in postmenopausal women.^75,76

Black cohosh has been shown to improve bone mineral density in animals fed a low calcium diet,⁷⁷ but it has not been studied for this purpose in humans.

Boron supplementation has been reported to reduce urinary loss of calcium and magnesium in some,⁷⁸ but not all,⁷⁹ preliminary research. However, those who are already supplementing with magnesium appear to achieve no additional calcium-sparing benefit when boron is added.⁸⁰ Finally, in the original report claiming that boron reduced loss of calcium,⁷⁸ 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.

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.⁸² 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.

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.⁸² 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.⁸³ 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.

Interest in the effect of manganese and bone health began when famed basketball player Bill Walton’s repeated fractures were halted with manganese supplementation.⁸⁴ A subsequent, unpublished study reported manganese deficiency in a small group of osteoporotic women.⁸⁵ Since then, a combination of minerals including manganese was reported to halt bone loss.⁸⁶ 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.

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.⁸⁷ 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.

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.⁹¹ 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.

Some whey proteins may reduce bone loss.⁹² Milk basic protein (MBP) is a mixture of some of the proteins found in whey protein. A preliminary trial found that 300 mg per day of MBP improved blood measures of bone metabolism in men, suggesting more bone formation was occurring than bone loss.⁹³ A double-blind trial found that women taking 40 mg per day of MBP for six months had greater gains in bone density compared with those taking a placebo.⁹⁴ No osteoporosis-related research has been done using complete whey protein mixtures.

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.⁹⁵ 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,⁹⁶ and urinary loss of zinc has been reported to be high.⁹⁷ 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.⁹⁸ 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.⁹⁹ 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.