By Dr. John Neustadt

Dietary supplements for bone health are big business. According to the dietary supplement industry publication, Nutraceuticals World, the bone and joint dietary supplement market was $250 million in the U.S. alone in 2015. As people age they tend to become more concerned with their bone health, so it’s not surprising that this market niche continues to grow.

But for all the hard-earned money people are spending to protect their bones, are they getting their money’s worth? Are you protected as much as possible, or as much as you think you are? Understanding how to evaluate research on nutrients and dietary supplements is important for helping you make the best possible decisions for your health. So, let’s review what the science says for the most common bone-building nutrients.

Calcium and Vitamin D

When most people think about nutrients for bone support, the two that most often come to mind are calcium and vitamin D. The FDA allows supplement companies to claim that “Adequate calcium and vitamin D throughout life, as part of a well-balanced diet, may reduce the risk of osteoporosis.” And doctors routinely recommend these two nutrients.

But do calcium and vitamin D promote healthy bone density and maintain strong bones as indicated by reducing fractures? 

One study evaluated 2532 people (average age, 73 years; 59.8% female) who supplemented with 400 IU vitamin D3 and 1000 mg calcium as calcium carbonate daily. They concluded that this combination reduced fractures by 16%.¹ In a systematic review of the research, another study determined that calcium plus vitamin D3 may reduce fractures by 18%.²

Which form of calcium is best?

Calcium carbonate is the most common form of calcium in supplements, but this mineral is poorly absorbed and can cause constipation.³ Absorbing calcium carbonate requires stomach acid to separate the calcium from the carbonate. As we age, however, low stomach acid becomes more common. An estimated 10–21% of people 60-69 years old, 31% of those 70-79years old, and 37% of those 80 years and older have low or no stomach acid.⁴ Stomach acid production is also low if you take acid blocking medications, have an untreated Helicobacter pylori (H. pylori) infection, have an autoimmune condition or you’re chronically stressed.

On the other hand, calcium citrate, calcium malate and calcium as an amino acid chelate are absorbed much easier than calcium carbonate. For example, the absorption of calcium citrate is approximately 24% higher than calcium carbonate. And when stomach acid is low, you absorb 200% more calcium from calcium citrate compared to calcium carbonate.⁵ This is why calcium citrate (and vitamin D3) is in Osteo-K and Osteo-K Minis. 

Bottom line for calcium and vitamin D: The bottom line for these research studies is that calcium and vitamin D3 may reduce fractures by about 16%. 

Vitamin K2 (MK4 and MK7)

MK4 and MK7 are two types of natural vitamin K2 commercially available in dietary supplements to promote bone health. MK4 is the major form of vitamin K that accumulates throughout the body—in the testes, pancreas, kidneys, brain and arteries.^6,7 In fact, tissues that accumulate high amounts of MK4 have a remarkable capacity to convert up to 90% of the available K1 into MK4.^8,9 This hints at MK4s wide-ranging benefits beyond bone health.

There are two crucial questions to ask when considering a bone health dietary supplement that contains MK4 or MK7. They are:

1. Has the form of vitamin K2 (MK4 or MK7) been shown to keep bones strong as indicated by fewer fractures in clinical trials?
2. Is the dose of the vitamin used in the product the same amount used in clinical trials and shown to work?

For these two questions, the research overwhelmingly supports the MK4 form of vitamin K2. MK7 has never been shown to reduce fractures as the primary endpoint in clinical trials. In contrast, the benefits of MK4 for bone health have been studied in 28 clinical trials with more than 7,000 people. Not only have researchers repeatedly concluded that MK4 (45 mg/day) supports healthy bone laboratory markers and bone density, but seven clinical trials specifically evaluated MK4’s ability to maintain strong bone by looking at fractures.

In fact, MK4 (45 mg/day) has been so well researched that it’s the only form of vitamin K2 with an approved health claim for bone support from the Ministry of Health in Japan.¹⁰ MK4 is also the only form of vitamin K2 shown to promote healthy bone mineral density, support healthy bone matrix and bone marrow, maintain strong bones and promote brain, immune and liver health.

Clinical trials using 45 mg per day of MK4 show this dose, and only this amount, promotes healthy bone density and maintains strong bones as indicated by—in one study—by up to 87% fewer fractures independent of the number of falls.¹¹ Since different clinical trials can come up with different results, pooling data from many clinical trials into what researchers call a meta-analysis can provide a clearer picture. Fortunately for us, two groups of researchers did exactly that for MK4.

A review of clinical trials published in 2006 concluded that MK4 maintains strong bones as indicated by 60% fewer vertebral fractures and 76% fewer nonvertebral fractures in study volunteers.¹² A more recent study came to similar conclusions. A 2015 meta-analysis concluded that taking MK4 (45 mg/day) reduced overall fractures by 53% in in clinical trials.¹³

MK4 is not only helpful, it’s safe at 45 mg/day and even at higher amounts. Published research has documented the safety in humans of 135 mg/day of MK4, and 250 mg/kg body weight per day in rats.^14,15 These studies also concluded that MK4 does not increase the risk for blood clots. To put the animal dose in perspective, if a typical adult weighs 150 pounds and takes 250 mg of MK4 per kg body weight, they’d consume 17,000 mg (17 kilograms!) of MK4. That amount is nearly 380 times more than the 45 mg/day used in the clinical trials.

Published studies have followed more than 7,000 volunteers for up to six years without any dangerous side effects from taking 45 mg and higher of MK4 daily. The only known exception to MK4’s safety is when people are taking the medication Warfarin (Coumadin). This blood thinner works by blocking the ability of vitamin K to promote blood clotting. When someone on warfarin takes vitamin K it counteracts the medication. For other types of blood thinners, like Lovenox (enoxaparin), which does not interfere with vitamin K, MK4 does not interact negatively with the drug. Similarly, there are no known contraindications to taking MK4 with osteoporosis medications.

Bottom line for vitamin K2: Only the MK4 form of vitamin K2, which is in Osteo-K and Osteo-K Minis, and only in the amount of 45 mg per day taken in divided doses has been shown to promote healthy bone density, support bone matrix health and maintain strong bones as indicated by 70% fewer fractures in clinical trials.

Boron

Boron is a trace mineral that was first discovered in 1910 as being required for plant development and health. In 1985 researchers discovered that humans also require boron in tiny amounts. However, there are no studies showing that boron improves bone mineral density, decreases bone loss or decreases fractures. Multivitamin and mineral supplements will often contain this nutrient anyway. But for building stronger bones and reducing fractures, there are no clinical trials supporting its use in a bone support dietary supplement.

However, in clinical trials boron has been shown to support joint health, joint mobility and physical function, which is why it’s in Joint Relief.

Bottom line for boron: Boron has never been shown to reduce fractures or boost bone density.

Strontium

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 bone health supplements. As of August 2022, when I last updated this blog, there were no published clinical on strontium citrate for bone health.

In contrast, strontium ranelate is approved for osteoporosis treatment in most of Europe but not in the US. Studies in rats concluded that strontium ranelate incorporates into bone, decreases bone loss and can increase bone density.¹⁶ A laboratory study determined that strontium ranelate can promote osteoblast production.¹⁷ Clinical trials have shown that taking 500-2000 mg per day of strontium ranelate can decrease vertebral fractures by 23% to 49% as well as increase bone mineral density.^18,19 Notably, in six large with 6762 woman, strontium ranelate did not reduce hip or other non-vertebral fractures.^18-23

Despite these studies, you may want to think twice before taking strontium for several reasons. First, strontium creates false bone density test results. Since strontium is heavier than calcium, 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.” Unless the radiologist understands this and uses a mathematical calculation to correct for this, the bone density scan will be inaccurate.¹⁸ Since radiologists are not taught this in medical school or residency, even if you tell them that you are taking strontium, the radiologist most likely won’t know how to correct for it to provide an accurate result. Strontium may also interfere with calcium absorption, which is why people taking strontium are advised to take it away from calcium.

Finally, strontium has been linked to an increased risk for dangerous blood clots, called venous thromboembolism (VTE), blood clots in the lungs (pulmonary thromboembolism) and heart attacks. According to a 2014 comparison of European regulatory data and publications for strontium (in the form of strontium ranelate), “the number of fractures prevented by strontium use is similar to the number of extra cases of venous thromboembolism, pulmonary embolism and myocardial infarction caused by strontium.”²⁴ While studies showed strontium reduces fracture risk, it’s just as effective at increasing your risk for a potentially deadly blood clot and heart attack.

Bottom line for strontium: Strontium as strontium ranelate supports bone health; however, strontium may interfere with calcium absorption, creates false bone density test results and has been linked to increased risks for blood clots and heart attacks.

Magnesium

Magnesium may play a role in promoting
bone health. Yet only one small clinical trial, conducted in 1993, has been published on the ability of magnesium to build bone.²⁵ 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 density. However, a more recent study evaluating data from 73,684 postmenopausal women concluded that magnesium intake had no effect on fracture risk.² 

I’ve seen on the internet claims that calcium and magnesium are required for calcium absorption and magnesium therefore must be in a bone health supplement. In more than two decades of research and clinical work, I have yet to see any studies supporting that claim. Plus, in the clinical trial using 45 mg/day of MK4, the only other nutrients used in some of the studies were calcium and vitamin D3. They had no other ingredients. Magnesium simply was not required to get the incredible results seen in the MK4 studies.

Bottom line for magnesium: Magnesium has never been shown to reduce fractures. And, in fact, the incredible fracture reduction of more than 70% seen in clinical trials using MK4 (45 mg/day) didn’t use magnesium. Eating more magnesium-rich whole foods (eg, green leafy vegetables) and taking a high-quality multiple vitamin and mineral supplement is a great way to get enough magnesium.

Melatonin

Not getting enough sleep is associated with significantly lower bone mineral density and increased osteoporosis risk.²⁷ And since not getting enough sleep decreases your balance, coordination and reaction time, it also increases your risk for falls and fractures.

Melatonin is a popular sleep dietary supplement that a lot of people use. Your body naturally produces melatonin in the pineal gland in your brain and in your gut. While most people only think about melatonin for helping them sleep, melatonin also helps your bones. Melatonin suppresses bone loss and promotes new bone formation.²⁸

The hypothesis that melatonin might be helpful in promoting bone health was tested in a 2015 study with 81 postmenopausal women.²⁹ This placebo-controlled, randomized clinical trial had women taking one mg of melatonin and three mg of melatonin or placebo at bedtime for one year. After one year they found that bone mineral density (BMD) significantly increased in women taking both one mg and three mg of melatonin, with the higher dose providing greater benefit. In women taking three mg of melatonin, femoral neck BMD increased 2.3% and the spine BMD increased 3.6%. However, BMD did not increase at any other sites (eg, the forearms or wrists). Additionally, the researchers did not evaluate whether taking melatonin also reduced fracture risk. Hopefully, future research will evaluate whether melatonin reduces fractures.

Bottom line for melatonin: Melatonin is important for sleep and supports bone health, but hasn’t been shown to maintain strong bones as indicated by fewer fractures in clinical trials. Melatonin is included in Sleep Relief. 

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 keeps bones strong.

Bottom line for soy isoflavones: Inconsistent evidence for bone-building and never been shown to maintain strong bones as indicated by reducing fractures in clinical trials.

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.

Bottom line for horsetail (Equisetum arvense): Never been shown to build stronger bones or reduce fractures.

Omega-3 Fatty Acids

Omega-3 fatty acids are polyunsaturated fatty acids that balance inflammation and support cardiovascular health. 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 promote healthy bone density or maintain strong bones. There are, however, many studies showing that taking omega-3 fats, like EPA and DHA in Best Catch Omegas. promotes cardiovascular health, brain health and healthy inflammation balance.  

Bottom line for omega-3 fatty acids: Never been shown to promote healthy bone density or maintain strong bones.

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