Scientists at the leading edge of osteology (bone research) are discovering that in addition to immune strength, blood cell production, and nervous system function, a healthy skeletal system is also essential to insulin sensitivity, energy metabolism, and weight management.1-4
The common bone disease osteoporosis accounts for 2.6 million doctors’ office visits and 180,000 placements in nursing homes across the country each year. According to the Surgeon General, by 2020 this potentially life-changing condition will afflict nearly half of all Americans over 50.5
Behind this alarming trend lies an even greater threat to the public health most doctors don’t know about. It turns out that strong, healthy bones play a far greater role in overall health than previously known.
In this article, the most recent data on these findings are detailed. You will also discover how calcium, magnesium, and potassium, along with vitamins D3 and K, act to optimize these functions for bone strength and system-wide health.
Until recently, the human skeleton was known to serve three basic functions.6 The first was its role in providing structural support for muscles and protection for internal organs.6 The second was its function as a reservoir for important mineral ions, especially calcium and magnesium, which are vital to nerve and muscle cell functioning and electrical conduction.6-8 Finally, the marrow space of many bones harbors all of the body’s blood-producing tissues and a major part of the cellular immune system.6
Just five years ago, however, scientists discovered a fourth, unexpected function.1 Bone-forming cells called osteoblasts were found to produce a hormone-like signaling protein called osteocalcin.9 It was further revealed that osteocalcin stimulates pancreatic insulin secretion and improves insulin sensitivity in tissues throughout the body.1,2,10-12
Osteocalcin reduces fat tissue deposition,2 while higher osteocalcin levels are associated with lower levels of leptin.13 As you read next, suppressing excess leptin is important in weight management.
Sometimes called the “hunger hormone,” leptin induces the feeling of being full after a meal. It plays a key role in regulating energy intake and energy expenditure, including appetite and metabolism. Higher leptin levels are paradoxically detrimental; as with insulin, you can develop leptin resistance that keeps you from feeling full. Obese individuals exhibit this resistance.14 Pathologically elevated leptin levels are detrimental to multiple tissues in the body and correlate with insulin resistance, inflammation, stroke, hypertension, and other dangerous health conditions.2,15-17
High leptin levels also exert an adverse effect over osteocalcin function:18 the more leptin your body’s fatty tissue produces, the less osteocalcin your bone cells release, and the worse your insulin resistance becomes.3 And in a final unexpected discovery, leptin achieves that effect by suppressing your osteoblasts’ activity, decreasing your ability to build new bone, and threatening your bone health.18
An additional indicator of how good bone health affects longevity is the now well-understood relationship between skeletal health and atherosclerosis.19 Via a variety of mechanisms, as calcium leaves the bones in the process of osteoporosis, it builds up instead in blood vessel walls, leading to dangerous calcified plaque deposits.20,21 Those deposits can rupture, causing an immediate arterial blockage and producing a sudden heart attack or catastrophic stroke.
It is this close interrelationship between bone health and total body health that has intensified scientific interest in identifying nutritional strategies to optimize bone health and strength.1
Most doctors don’t know about these new findings. And most Americans, including many health-conscious individuals, don’t get enough of the nutrients they need to support healthy bones. Adequate bone nutrition hinges on the following group of nutrients that work synergistically to optimize skeletal health and ward off multiple diseases of aging.22-24
Calcium accounts for 1-2% of adult human body weight, with more than 99% of total body calcium residing in the teeth and bones.25 The remaining 1% is used in our electrically active tissues such as nerve and muscle, where it plays a vital signaling role. Thus the skeleton is the body’s only storehouse of the calcium we need to sustain life itself, yet as we age we see a progressive decrease in the amount of calcium in our bones.25 Consuming a readily-absorbed form of calcium, then, is essential for restocking that reservoir—but many people do not ingest adequate amounts of calcium.25
The mainstream medical establishment has stubbornly denied the value of calcium supplementation for years, arguing that human studies under controlled conditions were inconclusive.26 A more careful and detailed review of recent studies, however, reveals flaws in their conclusions. Most notably, in outpatient studies, patients’ adherence to the supplementation regimen was generally poor—in other words, participants weren’t actually taking the calcium doses that researchers thought they were.26 A recent re-analysis of five of those flawed studies showed that patients who took the required doses of supplements indeed had significant reductions in osteoporosis fracture risk.26 Studies designed to optimize patients’ adherence to supplementation regimens have also demonstrated improved bone health and reduced risk of fracture.22,27,28
Not all calcium is alike. Dicalcium malate is an especially rich source of elemental calcium since it is comprised of two calcium molecules attached to each malic acid molecule. In a study of calcium absorption in humans, dicalcium malate demonstrated the longest half-life and greatest bioavailability, compared to several other forms of calcium.29 Calcium bis-glycinate consists of calcium chelated to the amino acid glycine, which allows it to be easily absorbed and utilized by the body. Both dicalcium malate and calcium bis-glycinate are easily assimilated, well tolerated, and effective at improving bone mineral density, an important measure of bone health.30 These mineral formulations represent outstanding forms of calcium for those seeking to optimize their bone health.
Daily doses averaging 1,000 mg are recommended for adults. For older women, the recommendation is 1,200 mg daily.31 Higher doses don’t provide additional benefit, and doses greater than 3,000 mg per day may be associated with kidney stones and other undesirable outcomes.32
In order to absorb calcium from the diet or from supplements, the human body requires vitamin D. For years, we believed that promoting calcium absorption from the intestinal tract was the chief function of vitamin D.33 But over the past decade there has been an explosion of scientific discoveries about vitamin D’s multiple roles throughout the body.34 We now recognize that vitamin D functions as a hormone, with receptors located in at least 35 different tissue types.34,35 That means the body’s overall requirement for vitamin D is much greater than we originally realized.33,36
With regard to bone health, vitamin D not only promotes calcium absorption but also its proper deposition in bone tissue, where it helps maintain the skeleton’s basic function as scaffold and protector of soft tissues.37 Elsewhere in the body, vitamin D acts at its specific receptors to promote immune function, subdue inflammation, reduce arterial calcification, enhance cardiac function, improve brain and nerve tissue performance, and even prevent cancer by regulating the cell replication cycle.34,38,39 Conversely, vitamin D deficiency is associated with not only bone diseases, but also cardiovascular disease, the metabolic syndrome, cancer, immune suppression, and autoimmune conditions such as multiple sclerosis, lupus, and inflammatory bowel disease.37,39-42
Despite the renewed scientific interest in vitamin D’s impact on human health, the prevalence of vitamin D deficiency remains high.43 Vitamin D3 (cholecalciferol) is synthesized in the skin from sunlight exposure and then converted into the active form, 1,25-dihydroxyvitamin D (calcitriol), by the liver and kidneys.37 But even in sunny Southern California, where one would expect most people to have sufficient vitamin D levels, almost 20% of people in one study had low vitamin D3 levels in their blood.44 In less sun-exposed regions, deficiency rates in excess of 50% have been documented.35,45
And remember that “deficiency” means exceedingly low levels of vitamin D. In aging individuals who don’t take at least 5,000 IU per day of vitamin D, approximately 85% have insufficient or “less-than-optimal” blood levels of vitamin D (measured as 25-hydroxyvitamin D).46
The combination of our increased knowledge about the importance of vitamin D throughout the body, and the widespread lack of adequate levels, has resulted in a rapidly growing international call for increased vitamin D intake.33,45,47
Many experts in the field recommend supplementing with doses of 2,000-10,000 IU per day in order to achieve optimal total-body vitamin D status for optimal skeletal, cardiovascular, neurological, immunological, and metabolic health.45,48-50