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Osteoporosis Prevention
May 2008
ABSTRACT: The skeleton is a dynamic organ system. Bones are continually being built and broken down, the balance of these two processes amounting to the status of our bone health. As we age, the bone building processes decreases, while bone breakdown increases. This leads to reduced bone density, and in more severe cases, osteoporosis.
We can however, prevent, or reduce our risk of osteoporosis. There are a number of factors that contribute to our bone health. The combination of exercise and a healthy diet are important for healthy bones. Where a diet may be lacking, a nutrient supplement containing more readily absorbable forms of calcium, magnesium, manganese, phosphate, and zinc, along with co-factors including vitamins B9 (folic acid), C and D may be beneficial.
It is common knowledge that calcium intake is important for bone development and maintenance. But what about the many other essential nutrients needed for bone health. The human skeleton is the single largest organ system in the body. Composed of a complex mix of organic proteins and inorganic mineral crystals, bones are much more than just structural supports. They are the body’s main reservoir of minerals such as calcium and phosphorus, which are critical for virtually every organ system.
Bones are highly sensitive to hormonal changes. During puberty, when hormone levels surge, bones are stimulated to grow rapidly as teenagers become full-sized adults. Thus, it is not really surprising that in later years, as hormone levels decline, the bones become vulnerable.
Maintaining healthy bones goes far beyond calcium. Although vital, healthy bones also rely on other micronutrients including vitamin D.
Causes of Osteoporosis
Osteoporosis is defined as a reduction of bone mass, or bone density, which causes bones to become brittle and fragile. People afflicted with osteoporosis are at an increased risk of bone fractures, the more common being the hip, spine, and wrist. Fractures associated with osteoporosis are debilitating and costly. Often, there’s a loss of function following hip and spine fractures, with mortality rates reported to be as high as 30 percent within the following 12 months.
Bone is living tissue comprised of an organic protein matrix (30 percent) and minerals (70 percent). Throughout life, cells known as osteoblasts construct the bone matrix with calcium. At the same time, cells called osteoclasts work just as busily to tear down and resorb the bone. These processes are generally fine balanced, being regulated by many factors, including systemic hormones and cytokines. Bone mass reaches its peak by the middle of the third decade of life and plateaus for about 10 years. During this time bone turnover is constant, bone formation matches bone resorption.
As our bodies age, this balance is lost. As hormone levels shift in midlife -- more drastically in women than in men -- the osteoclasts gain the upper hand, and bone mass begins to decline. Some bone is already being lost by the time women reach menopause, but the rate of loss can increase as much as tenfold during the first six years after menopause. This is the essence of primary osteoporosis, or osteoporosis that occurs as a natural part of aging.
From midlife onward, bone health is threatened by this process. To add to the problem, the osteoblasts may become less active with age. This process compromises the more dense bones of the hip, shin and pelvis.
Osteoporosis can also be caused by medications, especially glucocorticoids and corticosteroids, testosterone-deprivation therapy in prostate cancer patients, and any condition or behaviour that impairs calcium metabolism, including kidney disease, organ transplants, and smoking.
Advanced glycation end products (AGEs), are also implicated in bone loss. AGEs are formed when proteins interact with glucose molecules to form damaged structures in the body. The more AGEs that are present in bone means that there are fewer bone-building osteoblasts.
Nutritional Therapies: Calcium and Beyond
Calcium and vitamin D are the cornerstone of osteoporosis prevention, but they are not the whole story. Other nutrients are vital to having healthy strong bones including magnesium, phosphorus, vitamins C and B9 (folic acid or folate), zinc and manganese.
Calcium. Research has shown that calcium is beneficial for bone turnover and bone loss. Calcium intake is part of the foundation of osteoporosis prevention. Calcium requires the presence of vitamin D for maximum absorption.
Although calcium is readily available in dairy products and other dietary sources, people are often calcium deficient. The reasons for these deficiencies include:
• Decreased vitamin D availability, possibly due to kidney or liver problems or insufficient exposure to sunshine (ultraviolet radiation -- our primary source of vitamin D)
• Decreased gastrointestinal tract absorption due to stomach or intestinal problems
• Increased loss of calcium from the kidneys
• Increased loss of calcium from the gastrointestinal tract
• Low dietary calcium intake
• Medications that inhibit calcium absorption
There are many forms of calcium on the market, and many of these are not absorbed well. For instance, calcium carbonate, a common form of calcium is not absorbed as well as amino acid complexes (chelate), phosphate and citrate forms of the mineral.
Vitamin D. Vitamin D is a co-factor for calcium absorption, with hormone-like properties, facilitating and enhancing calcium absorption. Our main source of vitamin D is obtained through exposing skin to sunlight or ultraviolet radiation. Vitamin D deficiency is common in parts of the world that experience less sunlight.
People with lighter skin synthesize vitamin D in their skin easier than dark-skinned people. Some people must avoid exposure to sunlight for various reasons, such as incompatibility of sunlight with certain medications.
Magnesium. Magnesium is essential in bone formation and further assists calcium absorption. Magnesium deficiency is associated with osteoporosis and bone fragility or brittleness, while adequate magnesium intake is associated with increased bone mineral density.
Unfortunately, many people are thought to be deficient in magnesium, usually caused by malabsorption or high alcohol consumption. Dietary magnesium deficiency often occurs in people who do not consume enough dark green, leafy vegetables, which are rich in magnesium. If your diet is insufficient, magnesium should be taken as a supplement.
It is important that magnesium intake is in proportion with calcium however. High levels of calcium intake calcium intake can lead to an unfavorable calcium-to-magnesium ratio unless magnesium intake is increased accordingly. The optimum ratio of calcium to magnesium is believed to be approximately 2:1. The higher intake of magnesium is also important to protect against atherosclerosis.
Phosphorus. Phosphorus (or phosphate) regulates bone formation, inhibiting bone resorption and affecting calcium metabolism regulation. Because of this role, as with magnesium, consumption of phosphorus is important in limiting calcium absorption.
Vitamin C. Vitamin C (ascorbic acid) is essential for the formation of collagen and the stimulation of proteins derived from osteoclasts. Studies show that vitamin C contributes to increased bone mineral density by improving bone turnover. Increased antioxidant intake, with the inclusion of vitamin E, has been associated with a reduced risk of hip fracture, especially among smokers. It is also necessary for the synthesis of steroid hormones and neurotransmitters, which are vital to bone formation. Vitamin C also acts as a co-factor for iron, improving iron uptake and availability. Vitamin C’s powerful antioxidant properties protects the body from cytokines that are produced during bone breakdown.
Vitamin B9 (Folic acid/folate). Elevated homocysteine is considered a possible risk factor for osteoporosis, especially in women. Folic acid in combination with vitamins B6 and B12 can assist in lowering homocysteine. Folate along with vitamin B12 have been shown to reduce the risk of hip fracture in elderly patients.
Zinc. The role of zinc in osteoporosis is less well understood, but it is increasingly apparent that zinc deficiency is a risk factor for osteoporosis. It has been suggested that a deficiency in zinc may lead to the increase of natural anticoagulants in the blood. Zinc possesses cell protective properties, as it has been shown to limit the damaging effects of alcohol on bone.
The importance of a balanced diet
The above ingredients can be difficult to obtain in sufficient amounts, even in a balanced diet. If your intake falls short of what you require, supplementation can be beneficial.
Not everyone is aware of the importance of a balanced diet. The inclusion of vitamins and minerals as supplements are intended to be just that – supplementation of a normal diet. Supplements cannot be your sole source of essential nutrients, so supplements in combination with a (preferably) healthy diet may be required.
Apart from the nutrients mentioned above, the following nutrients are also important for cell metabolism and bone health.
Copper plays an essential role in bone metabolism and turnover and has been shown to improve bone density over time. Copper occurs naturally in vegetables, legumes, nuts, grains, and fruits, shellfish, avocado, beef, and animal organs, such as liver and kidney.
Boron assists with calcium absorption and bone formation. It maximises the body’s utilization of calcium, vitamin D and magnesium, being shown to possess antiosteoporotic activity. Boron is widely available from many food sources, being beneficial when deficient in other nutrients including vitamin D, magnesium, and potassium.
Silicon is also important to bone health. A study of large Framingham Heart Study found that silicon intake was positively related to increases in bone mineral density in the hip and spine. Silicon is widely available from a number of food sources.
Bioflavonoids (isoflavones) are phytoestrogens including rutin, quercetin, hesperidin, and eriodictyol. They are found in onions, peppers, garlic, black currants, blueberries, red berries, buckwheat, and green tea. These nutrients have been shown to stimulate bone morphogenetic proteins, which are known to increase bone formation.
Vitamins B6 and B12 have been implicated in reducing levels of homocysteine, a possible risk factor for osteoporosis, especially in women. Vitamin B12, together with folic acid and vitamin B6, can lower homocysteine. Vitamin B12 deficiency has been associated with decreased bone-mineral density in the hip, while vitamin B12 and folate have been shown to reduce the risk of hip fracture in elderly Japanese people. Good sources of vitamin B6 include meat, whole grain products, vegetables, and nuts. Vitamin B12 is found in foods of animal origin including meat (especially liver and shellfish) and dairy products.
Vitamin K facilitates the activity of calcium in bone building. Vitamin K works as a co-factor with vitamin D, enabling vitamin D to be utilised properly in maintaining bone integrity. Vitamin K is necessary for the activation of osteocalcin, a protein highly concentrated in bone, which allows calcium to bind to the bone matrix. Osteocalcin that has not been appropriately synthesized by vitamin K may lead to low bone mineral density and an increased risk of osteoporosis.
Vitamin K intake has also been seen to increase the bone-building protein gamma-carboxyglutamic acid in women, while slowing calcium loss by one-third in people more susceptible to calcium loss.
Vitamin K is found chiefly in leafy green vegetables, including cabbage, cauliflower, broccoli, and brussels sprouts, and in fruit such as avocado and kiwifruit. Other sources include meat, eggs, dairy and natto.
Conventional Treatment of Osteoporosis
In many cases, the first exposure to treatment is often emergency medical treatment to repair a fractured bone. Hip fractures almost always require surgery, ranging from pins and plates (to support the hip), to total hip replacements. For painful spinal fractures, painkillers may be recommended, along with anti-inflammatory medications. Other fractures, such as wrist or ankle fractures, are often treated with supportive care.
Exercise is highly recommended. Weight-bearing exercise has been shown to reduce the rate of bone loss among postmenopausal women, although it does not seem to increase bone mass. Exercise promotes healthy joints, ligaments, and muscles, which make falling less likely.
There is also pharmacological and hormonal treatment, where a number of agents or drugs may be prescribed.
Hormone replacement therapy (HRT) or estrogen replacement therapy (ERT) is often prescribed to increase bone mineral density. Many studies have proved that estrogen replacement therapy can improve bone turnover and reduce the risk of fracture.
The benefits of estrogen replacement therapy, however, has to be weighed against evidence linking conventional estrogen replacement therapy to increased risk of breast cancer, stroke, coronary heart disease potentially leading to a heart attack, and blood clots, increasing the risk of deep vein thrombosis and pulmonary embolism.
These findings had a dramatic effect on the number of women taking conventional hormone replacement therapy: some studies report that as many as 80 percent discontinued their treatment after the results were made public.
Bisphosphonates are a class of drugs that interfere with osteoclast function and reduce the number of osteoclasts, causing an increase in bone mineral density with a reduced risk of fractures. They are used to reduce the risk of fracture among people with glucocorticoid-induced osteoporosis. These drugs have side effects including gastrointestinal complications (esophagitis, gastritis, and diarrhea), and serious eye problems including acute glaucoma. Bisphosphonates have also been linked to osteonecrosis (death of the bone) in the jaw.
Phytoestrogens
Considering the health risks associated with conventional HRT, many women are reluctant to consider ERT. Phytoestrogens such as soy isoflavones and chasteberry provide a possible alternative. We now know that these compounds can bind directly to cellular oestrogen receptors, and can act as selective oestrogen receptor modulators (SERMs), essentially meaning that they may exert oestrogenic activity in certain parts of the body, but not necessarily in others. These compounds appear to benefit bone health with long term use and benefits have also been observed in cardiovascular and neural (brain) health.
A six-month study to investigate bone density and bone mineral content in response to soy therapy found that, women receiving phytoestrogens had a significant increase in bone density and bone mineral content in the lumbar spine and in other skeletal areas when compared with placebo. Another study involving 24,400 postmenopausal women also found that phytoestrogens reduced the risk of fracture in postmenopausal women.
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