Osteoporosis and Bone Health
Imagine the internal structure of bone as being like the wood foundation of a house. The process of osteoporosis is similar to what happens during a termite infestation in a home’s foundation. At some point, so much wood is consumed that the strength of the foundation is compromised and it begins to fail. This is not unlike the progression of osteoporosis; over time, the internal architecture of bone is eroded as a result of a number of factors that eventually increase your risk for fracture. The term osteopenia, or low bone mass, refers to a condition of reduced bone density that has not yet progressed to osteoporosis. Those diagnosed with this condition should still be monitored to ensure that the condition does not get worse.
Osteoporosis is the most common disease affecting the skeleton and is one of the most important public health issues facing America. More than 50 percent of women and 25 percent of men over the age of 50 will suffer an osteoporotic fracture at some time in their lives. Sadly, one in six women will experience a hip fracture, the most devastating type of osteoporotic fracture. This risk is equal to a woman’s chance of developing breast, uterine, and ovarian cancer combined. Newest estimates of hip fracture show that while the number of hip fractures among women will decrease slightly over the next 20 years, the number of hip fractures among men will rise more than 50 percent. While education, new medications, and improvement in healthy behaviors may explain the reduction of fractures in women, the fact that men are now living longer explains the staggering projections for osteoporosis and subsequent fracture.
Fracturing a bone is a serious complication of osteoporosis. Fractures can cause severe pain, affect posture and appearance, and even be deadly. Fractures of the spine can cause a person to lose height and become permanently hunched over. An estimated 20 percent of people who fracture a hip die within one year due to complications of the broken bone or the surgery to repair it. Most who survive a hip fracture never regain their previous level of independence. Although an osteoporotic fracture can be devastating, the good news is that because osteoporosis progresses slowly, you can take a number of steps throughout your life to reduce your risk of developing it.
Causes of Osteoporosis
During growth and young adulthood, the skeleton is busy changing in size, shape, and density to ultimately support the physical needs of an adult. In adulthood, the skeleton remains relatively stable but is still constantly undergoing a process called bone remodeling, in which bone repairs and replaces itself in roughly the same amount. Many processes, however, can “uncouple” bone balance. With normal aging, bone breakdown outpaces replacement, causing up to 1 percent of bone to be lost per year after around age 30. Certain conditions—such as estrogen loss from menopause or reduced testosterone in men, an overactive thyroid gland, diabetes, certain autoimmune diseases and cancers, and gastrointestinal disorders like celiac disease or irritable bowel syndrome—may increase bone breakdown and slow down the bone replacement, causing further overall loss of bone. On the other hand, pharmaceutical agents that stop the breakdown of bone, as well as physical activity, which causes a bone to be built, can cause a net bone gain.
Because bone is a dynamic tissue throughout life, strategies to slow bone breakdown and to build new, stronger bone are useful at any life stage. Some of the factors you can control, and others you cannot.
On the left side of the scale are factors that have a positive influence on a bone; the right side of the scale includes factors that have a negative influence. Positive factors may contribute to bone gain while negative factors may cause bone loss. If you’re interested in learning more about your risk for osteoporosis, the World Health Organization has adopted a scientifically validated tool that predicts the 10-year probability of sustaining an osteoporosis-related fracture called the WHO Fracture Risk Assessment Tool, or FRAX. This tool enhances patient assessment by integrating clinical risk factors alone or in combination with your bone mineral density (if you know it):
Risk Factors for Osteoporosis
Your risk of osteoporosis is influenced by many factors, some of which you can control or modify, and others that are outside of your control.
Risk Factors You Cannot Control
- Being female
- Having a thin or small frame
- Being of advanced age
- Having a family history of osteoporosis
- Being postmenopausal, including early or surgically induced menopause
- Being male with low testosterone levels
- Being Caucasian or Asian (although African Americans and Hispanic Americans can be at risk as well)
Risk Factors You Can Control
- Having a diet low in calcium, vitamin D, and protein
- Being inactive
- Smoking, including exposure to secondhand smoke
- Excessive use of alcohol (more than three drinks per day)
Risk Factors You May Be Able to Control
- Loss of menstrual periods not related to menopause (amenorrhea)
- Anorexia nervosa (eating disorder characterized by low body weight) or bulimia nervosa (purging food, which reduces absorption of vital nutrients)
- Prolonged use of certain medications, such as corticosteroids and anticonvulsants
- The presence of other chronic diseases such as heart disease, high blood pressure, or high cholesterol related to poor lifestyle choices or obesity.
Smoking and alcohol consumption are two lifestyle factors you can manage. Avoid smoking, being in contact with secondhand smoke, and excessive alcohol consumption, as these influence the absorption of key nutrients. Other controllable factors that affect the health of your bones include reproductive hormone levels, dietary adequacy (namely, of calcium and vitamin D), and physical activity. Near or at the onset of menopause, typically around age 50, women’s bodies produce less estrogen. This loss of estrogen can cause bone to be lost two to five times more quickly than bone loss as a result of age alone. Although estrogen and hormone therapy have been shown to effectively stop menopause-related bone loss , many women choose not to take hormones because of a history of breast cancer or other concerns, such as a potential increased risk of heart attack or stroke (6). For men, age-related reductions in testosterone and estrogen may also contribute to fracture risk. Although some men with osteoporosis also have low testosterone levels, low testosterone does not inevitably lead to osteoporosis.
Most of the options for maintaining normal hormone levels are drug related and are discussed later in this chapter, but some behaviors can also influence hormone levels. In particular, you should avoid excessive exercise training coupled with strict dieting. Women who exercise excessively and restrict their eating are prone to disturbances in their menstrual cycle as a result of low estrogen levels caused by low energy availability. In other words, you must consume enough calories each day to support the amount of exercise you do. The amount and type of exercise recommended in this book would not put someone at risk for such a problem. This chapter explains which types of exercise are best for your bones to keep them healthy while helping you better understand all the factors that influence your risk of osteoporosis so you can make the best choices.