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Bone Support Dietary Supplements

Many companies produce dietary supplements for bone health. Many people buy calcium and other bone health supplements thinking that they might promote bone growth or reduce osteoporosis risk. By definition, dietary supplements are not approved by the FDA to diagnose, treat or prevent a disease; however, manufacturers of some dietary supplements can make certain claims, as approved by the FDA. For example, labels for calcium supplements can state that calcium “reduces osteoporosis risk.”1

Other ingredients you might find in bone strengthening supplements include boron, strontium, magnesium, soy isoflavones, vitamin K2 (as MK4™ or MK7), horsetail (Equisetum arvense) and omega-3 fatty acids. So what’s the evidence for their effectiveness in promoting bone health?

Calcium and Vitamin D

Calcium and vitamin D may reduce osteoporosis risk according to the FDA. . In terms of reducing fractures, calcium may decrease fractures by about 16%.2

Vitamin K2 (MK4 and MK7)

MK4 and MK7 are two types of vitamin K2 that are commercially available in dietary supplements. However, MK7 has never been shown to reduce fractures. In contrast MK4 has been shown to decrease fractures, and has even been approved by the Ministry of Health in Japan since 1995.3 Multiple clinical trials using 45 mg per day of MK4 show that this amount, and only this amount, of MK4 taken daily may decrease fracturesby 80% or more.4,5,6 Even at extremely high doses in humans of 135 mg/day of MK4, and 250 mg/kg body weight per day in rats showed that MK4 does not increase the risk for blood clots.7,8 MK4 is understood to be safe at all amounts, and effective at promoting bone health and building strong bones when 45 mg/day are taken with calcium and vitamin D.


Boron, a trace mineral needed in only tiny amounts, was first discovered in 1910 as being required for plant development and health. In 1985 researchers discovered that humans also require boron. Some foods are good sources of boron, including pears, prunes, apples, raisins, and tomatoes. Studies have shown that 3 milligrams (mg) of boron daily reduces urinary excretion of calcium and magnesium, especially when dietary magnesium is low. Boron supplementation elevates the serum concentrations of 17 beta estradiol and testosterone, again only when dietary magnesium is low. This suggests that boron may promote bone health. However, there is no evidence that boron in bone health  supplements improves bone mineral density, decreases bone loss or decreases fractures.


Several rigorous clinical trials have evaluated strontium for its bone building effects. Strontium ranelate (SR) is a form of strontium salt from ranelic acid patented by a French company. SR is the only form of strontium that has ever been studied in clinical trials, and is not available in the US. Strontium citrate is the form of strontium available in osteoporosis supplements in the US and has never been studied in clinical trials for its bone building effects.

SR is approved for osteoporosis treatment in most of Europe but not in the US. Studies in rats concluded that SR does have an affinity for bone, decreases bone loss and can build bones.9 A laboratory study determined that SR can promote osteoblast production.10 Clinical trials in have shown that taking 500-2000 mg per day of SR can decrease vertebral fractures by 23% to 49%, as well as increase bone mineral density.11,12

People may want to think twice before taking strontium for several reasons. First, strontium is not approved by the US FDA. Second, strontium is heavier than calcium. As such X-rays from a bone density scan bounce off the strontium to a greater degree than calcium, and change what’s called the “refractive index.”13 Unless the radiologist understands this and uses a mathematical calculation to correct for this, the bone density scan will be inaccurate.14 Since radiologists are not taught this in medical school or residency, even if you tell them that you are taking strontium most probably the radiologist will have no idea how to correct for it and provide an accurate result.


Magnesium may play a role in promoting bone health. However, only one small clinical trial, conducted in 1993, has been published on the effectiveness of magnesium for building bone.15 This study concluded that taking a few hundred milligrams daily of magnesium (as magnesium hydroxide, one of the least absorbable forms of magnesium) may increase bone mineral density by one to eight percent. This evidence is quite weak.  While about 56% of adults do not consume even the minimum recommended daily allowance of magnesium,16 a good multiple vitamin should contain at least 100 mg of magnesium as an amino acid chelate, the most absorbable form of magnesium. Additionally, food rich in magnesium includes bran cereal, shredded wheat, brown rice, almonds (also an excellent source of calcium) and swiss chard. So following a healthy eating plan and taking a high quality multiple vitamin should provide all the magnesium you need.

Soy Isoflavones

Soy isoflavones refers to multiple naturally-occurring chemicals called phytoestrogens. As the name implies, these molecules have estrogenic activity. Since estrogen supplementation has been approved by the FDA as an osteoporosis treatment approach, soy isoflavones have been studied for their bone building effects. Observational studies and clinical trials have not shown any consistent evidence that soy isoflavones can build stronger bones.

Horsetail (Equisetum arvense)

Occasionally you may encounter horsetail (Equisetum arvense) in bone health supplements. This botanical is high in silicon and believed by some to promote bone health. However, there are no clinical trials showing that horsetail improves bone mineral density or decreases fractures.

Omega-3 Fatty Acids

Omega-3 fatty acids are polyunsaturated fatty acids that have anti-inflammatory actions and lots of research showing cardiovascular disease benefits. In fact, the American Heart Association (AHA) now recommends people consume 2000 mg daily of combined EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) for heart health. There are some bone building supplements that contain omega-3 fatty acids, but in much lower doses than those recommended for heart health. However, while theoretically plausible, there are no studies showing that omega-3 fatty acids build bone or reduce fractures.

Learn More

Why Osteo-K clobbers the competition: click to view a chart comparing Osteo-K to other leading calcium supplements, such as Viactiv, Citracal, Bone-Up, Os-Cal and Caltrate.

You can also learn more by reading about calcium supplements and bone health.