Understanding Osteoporosis

Osteoporosis

Osteoporosis is like a three-legged stool. All three legs of a stool are continually needed in their entirety to help maintain balance. If one of those legs becomes weakened or eliminated, the stool will fall. Osteoporosis works just the same way with nutrition, weight-bearing exercise, and estrogen serving as its three legs. Therefore when a leg of osteoporosis becomes absent or inadequate in an individual’s life, the condition worsens and overall health declines.

Osteoporosis is a condition in which the bones have thinned and weakened to the point where they can break easily. It is considered the “silent disease” because no symptoms or pain occur until a bone is actually broken. Osteoporosis is treatable, not curable, and responsible for costing the nation over nineteen billion dollars in 2005. Ten million Americans already have the disease, with women making up eight million of them. Thirty-four million Americans are at risk for osteoporosis. About one in two women over the age of fifty will break a bone because of osteoporosis, while one in four men will too. Men over the age of fifty will be more prone to breaking a bone from osteoporosis than actually getting prostate cancer. And twenty percent of seniors who break a hip die within one year because of problems related to the broken bone or the surgery taken to repair it (National Osteoporosis Foundation, 2010).

Bone is a living, growing tissue and made mostly of collagen, which is a protein that provides soft framework and calcium phosphate. This combination of calcium and collagen makes bones flexible, strong, and able to withstand stress. Before the age of 30, new bone is added faster than old bone is removed. This is what makes bones larger, heavier, and denser. Bone formation essentially outpaces resorption. Around the age of 30, peak bone mass is reached and bone resorption slowly begins to exceed bone formation. Osteoporosis is now more likely to develop if one did not reach optimal peak bone mass during bone-building years and does not currently work on keeping the three stool legs strong (NIH Osteoporosis and Related Bone Diseases National Resource Center, 2011).

In every osteoporotic situation, the affected bones have become less dense, more porous, and slower at recycling old bone cells and depositing calcium. But it is not the bone composition that changes with older age. It is the mass and density that decreases over time. This is why prevention is key and keeping all three legs of osteoporosis strong is essential starting from birth.

There are a number of risk factors that increase an individual’s chance of obtaining osteoporosis. Some are controllable, while others are not. Age, gender, family history, body size, ethnicity, and menopause are uncontrollable. Older individuals are more highly susceptible to bone changes because of the natural process of bones becoming thinner and weaker with age. Females have lighter and thinner bones than men and lose bone more quickly after menopause due to decreased estrogen levels. The same holds true when ovaries are removed because they produce most of the estrogen, which is what protects the bones. Genetics play a major role in developing osteoporosis, and individuals with smaller body frames, bones and body weights are more highly susceptible. In addition, Caucasian and Asian women are at a higher risk than their African American and Hispanic counterparts in developing osteoporosis (National Osteoporosis Foundation, 2010).

Those risk factors that are controllable are nutrition, exercise, smoking, alcohol intake, body weight, and medication use. Smoking is not only bad for your lungs, but it is also bad for your bones because of the toxic effects placed on osteoblasts, the cells responsible for bone formation. Smokers absorb less calcium from their diets, and female smokers have lower levels of estrogen and often go through menopause earlier. Heavy alcohol consumption may make an individual more prone to bone loss and fracture because of both poor nutrition and increased risks of falling. Even regular consumption of two to three ounces of alcohol a day can be damaging to the skeleton. Drinking heavily can also reduce bone formation and affect the body’s calcium supply.
Certain medications can cause bone loss and they are as follows: glucocorticoids, anti-seizure drugs such as phenytoin (Dilantin) and barbiturates, aluminum-containing antacids, certain cancer treatments, excessive thyroid hormone, and the gonadotropin-releasing hormone drugs that are used to treat endometriosis. Glucocorticoids are prescribed for a wide range of diseases like arthritis, asthma, Crohn’s disease, lupus, and other diseases of the lungs, kidneys, and liver.

The most important nutrients for fighting osteoporosis are calcium and vitamin D. The two go hand in hand. Calcium is a major building block of bones, while vitamin D is the “key” that unlocks the doors to the bones that allow calcium to be absorbed. If there is an inadequate amount of vitamin D in the body, it does not matter how much calcium is consumed because the bones will not be able to absorb it properly (WebMD, Inc 2005-2007). Low calcium intake throughout life is associated with high fracture rates, low bone mass, and rapid bone loss. Therefore, inadequate calcium supplies significantly contribute to the development of osteoporosis. Sufficient vitamin D levels will not only improve calcium, but it will also lessen the chances of falls and fractures occurring (NIH Osteoporosis and Related Bone Diseases National Resource Center, 2011).

The National Academy of Sciences developed recommendations for how much calcium and vitamin D should be consumed at every age. Young children 1-3 years old should get 700 mg of calcium a day. Children 4-8 years old should get 1,000 mg per day. Teenagers should get 1,000 mg a day. Adults up to age 70 should get 1,000 mg per day. Women 51 and over should get 1,200 mg a day. Finally, women and men 71 and over should get 1,200 mg per day. To unlock that calcium, it is recommended that 600 international units (IU) of vitamin D be consumed a day for ages 70 and under. For those aged 70 and over, 800 IU is recommended. However, osteoporosis experts may soon increase the recommendation to 800-1,200 IU (WebMD, Inc 2005-2007 ).
Foods are the best source for obtaining recommended levels of calcium and vitamin D. Calcium rich foods include the following: low-fat dairy products such as milk, yogurt, cheese and ice cream; dark green, leafy vegetables such as broccoli, collard greens, bok choy, and spinach; sardines and salmon with bones; oysters; clam; blue crab; shrimp; tofu; almonds; soybeans; baked beans; and foods fortified with calcium such as orange juice, cereals, oatmeal, and breads. Vitamin D rich foods are harder to get in the daily diet but include the following: egg yolks; saltwater fish; liver; and vitamin D fortified foods such as milk, orange juice, and breakfast cereals. The sun is also another great source to obtain vitamin D.

If food is not sufficient enough to maintain the recommended calcium and vitamin D levels, supplements are also an essential part of bone health. The amount of calcium supplementation needed depends on how much calcium is being obtained from food. The supplements are better absorbed when small doses (500 mg or less) are taken several times throughout the day. Checking supplement labels to ensure that the product meets United States Pharmacopeia standards is important, too. Calcium carbonate and calcium nitrate are two of the main calcium supplements, and most individuals better absorb them with food (NIH Osteoporosis and Related Bone Diseases National Resource Center, 2011).

Trace minerals such as copper, manganese, zinc, boron, and silicon also play an important role in keeping bones healthy and strong. Copper is needed for cross-linking collagen and elastin. Manganese is used for the biosynthesis of mucopolysaccharides in bone matrix formation. Zinc is responsible for osteoblastic activity, collagen synthesis and alkaline phosphatase activity. Then boron and silicon are needed for healthy bone formation. Contrarily, high levels of protein and sodium in the diet should be avoided because they increase calcium excretion through the kidneys. High sodium levels are dangerous because urinary sodium excretion is accompanied by calcium excretion (Holick, & Dawson-Hughes, 2004). As can be seen, good nutrition is vital in preventing osteoporosis.

Exercise, another one of the legs, is essential to bone health as well. Exercising can reduce the risk for osteoporotic fractures by enhancing the peak bone mass achieved during development and growth and slowing the rate of bone loss and reducing the risk of falls due to inadequate muscle strength and balance (Lippincott, Williams & Wilkins, 2010). Bones are living tissue, therefore; weight-bearing activities cause new bone tissue to form to make bones stronger. Osteoblast activity is stimulated when there is a pull of the muscle against bone when weight-bearing exercise takes place. In addition to stopping the loss of bone mass, exercise leads to increased fitness, which improves muscle control and helps prevent falls (Holick, & Dawson-Hughes, 2004).

Exercise prescription recommendations for osteoporosis are split into two types of populations, those with osteoporosis and those at risk. To be considered at risk, all the individual has to have is at least one risk factor (current low bone mass, age, and being famle) for osteoporosis. The FITT principle is used when prescribing exercise to both osteoporotic population, and it stands for Frequency, Intensity, Time, and Type. For the individuals at risk for osteoporosis, the following is their exercise prescription. Frequency is weight-bearing aerobic activity 3-5 times a week and resistance exercise 2-3 times a week. Intensity is moderate (60-80% 1-RM, 8-12 repetitions) to high (80-90% 1-RM, 5-6 repetitions) in terms of bone-loading forces like resistance activities. Time is 30-60 minutes a day of weight-bearing aerobic and resistance activities. Type is weight-bearing aerobic activities (tennis, stair climbing/descending, and walking with jogging intervals), jumping activities (volleyball and basketball), and resistance exercise (weight lifting).
For individuals with osteoporosis, the following FITT exercise prescription will help prevent disease progression. Frequency is weight-bearing aerobic activities 3-5 days a week and resistance exercise 2-3 days a week. Intensity is moderate intensity (40% to <60% VO2R or HRR) for weight-bearing aerobic activities and moderate intensity (60-80% 1-R, 8-12 repetitions) for bone-loading forces. Some individuals may be able to tolerate more, though. Time is 30-60 minutes a day of a combination of weight-bearing aerobic and resistance activities. Type is weight-bearing aerobic activities and resistance exercise. Overall, exercises that involve explosive movements, high-impact loading, twisting, bending, or compression of the spine should be avoided because pain should not be exacerbated.

There are no special considerations for exercise testing with individuals at risk for osteoporosis. However, some issues should be considered when exercise tests are performed on osteoporotic individuals. Use a cycle ergometer as an alternative to treadmill exercise testing to assess the patient’s cardiovascular function because those with severe vertebral osteoporosis experience pain when walking. Vertebral compression fractures that lead to height loss and spinal deformation can compromise ventilator capacity. Thus, center of gravity may be shifted forward in these individuals, affecting balance during treadmill walking. Lastly, there are no established guidelines for contraindications for maximal muscle strength testing, but this kind of testing may be contraindicated for patients with severe osteoporosis (Lippincott, Williams & Wilkins, 2010).

Estrogen, the last leg of osteoporosis, protects bones. Without it, bone density diminishes and osteoporosis sets in. Both men and women carry estrogen in their body, but women are at a higher risk for low estrogen levels because of menopause. Estrogen Replacement Therapy (ERT) is one method that can be used to reduce bone resorption and arrest postmenopausal bone loss in women. It is most effective if used during the first five to fifteen years after menopause, and if done so can even reduce fracture rates. Some evidence even supports that ERT, combined with high calcium supplementation, can result in increased bone mineral density. A smaller dose of estrogen may be effective in women who are also taking in 1500 mg of calcium a day. A high calcium intake, however, will not substitute for ERT in stopping postmenopausal bone loss. Some risks are associated with ERT and they are endometrial cancer, breast cancer, and return of the menses. Adding progestin can help lower the risk of endometrial cancer, though (Holick, & Dawson-Hughes, 2004).

One particular study gathered 18 women to assess total collagen content and collagen crosslink maturity in an iliac crest bone biopsy, before and after 6 years of higher-dose ERT. Estrogen stimulates osteoblasts and bone formation, and such an anabolic effect of ERT is beneficial in postmenopausal women with osteoporosis. The results from the assessment were compared with the serum estradiol level and bone mineral density. Total collagen content of cancellous and cortical bone increased, as did collagen synthesis. Furthermore, bone mineral density showed a rise in the lumbar spine and proximal femur, and serum estradiol and bone mineral density results coorelated with cortical bone collagen levels. Thus, long-term higher-dose ERT has a therapeutic role in postmenopausal women with osteoporosis because of its anabolic effect on bone (Khastgir, Studd, Holland, Alaghband-Zadeh, & Sims, 2001).

Understanding osteoporosis is important and keeping all three stool legs (nutrition, weight-bearing exercise, and estrogen) in check will help prevent the condition from developing or worsening. One last step in combating osteoporosis is staying in communication with your healthcare provider and undergoing medical tests to assess the body. A bone density test is the only test that can diagnose osteoporosis before a broken bone occurs. This test estimates bone density and the chances of breaking a bone. One of the more widely recognized bone mineral density tests is a dual-energy x-ray absorptiometry test (DXA). DXA tests can detect low bone density before a fracture occurs, confirm a diagnosis of osteoporosis, and determine rate of bone loss. The test is painless, too, much like having an x-ray done. If that bone density test shows that low bone density (osteopenia) is present, the fracture risk assessment tool called FRAX can estimate the chance of breaking a bone within 10 years. This helps in the process of deciding whether or not to take osteoporosis medication. Laboratory tests of the blood and urine can also be used to identify possible causes of bone loss. Some of the tests include the following: blood calcium levels, 24-hour urine calcium measurement, thyroid function tests, parathyroid hormone levels, testosterone levels in men, 25-hydroxyvitamin D test, and biochemical marker tests such as NTX and CTX (National Osteoporosis Foundation, 2010).

References:

Khastgir, G., Studd, J., Holland, N., Alaghband-Zadeh, J., & Sims, T.J. (2001). Anabolic effect of long-term estrogen replacement on bone collagen. Osteoporosis International, 12(465-470), Retrieved from http://search.proquest.com.proxy.bsu.edu/nursing/docview/848580432/12E17...

National Osteoporosis Foundation, . (2010). About Osteoporosis. Retrieved from http://www.nof.org

WebMD, Inc. (2005-2007). Nutrition and Osteoporosis. Retrieved from http://www.webmd.com/osteoporosis/nutrition-osteoporosis-eat-boost-bone-...

NIH Osteoporosis and Related Bone Diseases National Resource Center. (2011, January). Osteoporosis. Retrieved from http://www.niams.nih.gov/Health_Info/Bone/Osteoporosis/

Lippincott, Williams, & Wilkins. (2010). Acsm's guidelines for exercise testing and prescription. Baltimore, MD: Wolters Kluwer.

Holick, M., & Dawson-Hughes, B. (2004). Nutrition and bone health. Humana Press.