The skeleton is remarkable. It provides mobility, support,
and protection for the body. It also serves to store minerals, such as calcium
in the process of building bones. Bone is not a static organ, but constantly
adapts to the internal environment of the body. The development of the bony
skeleton likely began many eons ago, when animals left the calcium-rich ocean,
first to live in fresh water where calcium was in short supply, and then on dry
land where weight bearing put much greater stress on the skeleton. Bone
architecture is comprised of two main components: minerals (calcium,
phosphorous, magnesium) to give bone its strength, and connective tissue
(collagen) to give bone some flexibility.
Minerals in bone are released when hormones in the body,
such as parathyroid hormone (PTH), signal a need for increased blood levels of
those elements. The body controls the level of calcium in the blood very
closely, since it plays such a critical role in the health of all body organs,
especially nerves and muscle. Vitamin D is actually a hormone that is crucial
for bone health. It stimulates DNA in the intestines to produce more proteins
that increase the amount of calcium that can be absorbed. Additionally, vitamin
D acts to decrease the amount of calcium processed by the kidneys and
eliminated from the body in urine.
Bone health is influenced by diet, exercise, dietary
supplements, genetics, body size, habits (eg, smoking) and environmental
contaminants. One of the largest determinants in bone health is the ability for
the cells in the process of bone building to actively continue to break down old
bone and produce new bone. There are two cells in bone responsible for building
bones: osteoblasts and osteoclasts. An osteoblast (from the Greek “Osteo”
meaning “bone” and “blast” meaning “germ” or “embryonic) create new bone and an
osteoclast breaks down and recycles old bone.
This process of breaking down old
bone and creating new bone is called “bone remodeling.” Osteoblasts come from osteoprogenitor cells located in the
thin covering of the bone called the periosteum, and also in the bone marrow.
Osteoprogenitor cells are immature cells that mature into osteoblasts when they
receive specific chemical signals, such as growth factors. The primary growth
factor appears to be bone morphogenetic proteins. However, other growth
factors, such as fibroblast growth factor, platelet-derived growth factor,
transforming growth factor beta (TFG-beta) may also be important for maturing
osteoblasts, building bones and bone health.
Osteoclasts (from the Greek meaning “broken bone”) are
actually derived from immune system cells called macrophages. An osteoclast is
comparably much larger than an osteoblast and contains many nuclei. It also has
many vacuoles, which are storage area within cells. When an osteoclast is
actively breaking down bone it enlarges and creates a “ruffled border”
appearance when looked at under a microscope. Hormones required for osteoclast
formation include receptor activator of nuclear factor kappa beta (RANK) and
macrophage colony-stimulating factor (M-CSF). Interestingly, these hormones are
produced by osteoblasts, so there is constant communication between osteoblasts
and osteoclasts, which work together to keep the bone remodeling process in a
Steps to Slow or Stop Bone Loss
Men and women begin to lose bone at 0.5% to 2% per year
after their early 30’s. In women, an accelerated rate
of bone loss occurs during menopause and for about 10 years thereafter. Bone
loss increases your risk for osteoporosis and bone fracture. Maintaining and
building bone is crucial for long-term health, because 20% of people with
osteoporosis who fracture their hip die within one year, and 20% of those who
survive end up in a nursing home.
Many nutrients are important for bone health. Calcium and
vitamin D are often the only nutrients people think about. However, calcium and
vitamin D have only been shown to decrease fracture risk by about 18%.
Additionally, calcium and vitamin D alone do not build bones, they merely slow
down the rate of bone loss. Another nutrient that is too often overlooked is vitamin K. Many studies have
shown vitamin K to be an important nutrient for bone health. Studies have
tracked people’s eating habits over many years and concluded that the more
vitamin K people eat through food, which is found in green leafy vegetables
(kale, swiss chard, lettuce), the lower their osteoporosis risk.
Laboratory studies of vitamin
K2 show that it inhibits osteoclast maturation and actually helps stimulate
the destruction of osteoclasts, while simultaneously promoting osteoblast
activity. Furthermore, additional studies suggest that vitamin K2 promotes the
production of connective tissue in bone.
Regular physical activity is
important for bone health and reduces the risk of fractures. Like a healthy
diet, adequate weight-bearing physical activity early in life is important in
reaching peak bone mass.
Studies have confirmed the
beneficial effects of exercise on bone health. Weight-bearing physical
activities cause muscles and bones to work against gravity and stimulates bone
production. Exercise can increase muscle mass, strength, and balance, thereby
decreasing the risk for falling and suffering an osteoporotic fracture. Muscle
strengthening and balance exercises (eg, Chi Gong, Tai Chi) have been shown to
decrease risk for fall and fall-related injuries by 75% among women aged 75
years and older. In another study, one year of weight-bearing exercise training
in community-living women (ages 66 to 87 years) improved hip bone mineral
density by 8.4% compared to controls.
Examples of weight bearing physical activities include walking, jogging,
running, tennis or racquetball, field hockey, stair climbing, jumping rope, basketball,
dancing, hiking, soccer, and weight lifting.
Why Osteo-K clobbers the competition: click
view a chart
comparing Osteo-K to other leading calcium
supplements, such as Viactiv
You can also learn more by reading about MK7 and hip fracture.