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Bone Health and Osteoporosis: A Report of the Surgeon General

Chapter 7: Lifestyle Approaches To Promote Bone Health

• Key Messages
• Introduction
• Nutrition
  • Calcium
  • Vitamin D
  • Other Nutrients Important to Bone
• Physical Activity
  • Physical Activity for Children and Adolescents
  • Physical Activity for Adults
  • Physical Activity for Older Adults
  • Physical Activity for Those With Fragility Fractures
• Fall Prevention
• Other Aspects of a Bone-Healthy Lifestyle
• Summary
• Key Questions for Future Research
• References

Key Messages

• There is much that individuals can do to promote their own bone health, beginning in childhood and continuing into old age. These activities contribute not only to bone health, but to overall health and vitality.
• Since many nutrients are important for bone health, it is important to eat a well-balanced diet containing a variety of foods, including grains, fruits and vegetables, nonfat or low-fat dairy products or other calcium-rich foods, and meat or beans each day.
• Most Americans do not consume recommended levels of calcium, but reaching these levels is a feasible goal. Approximately three 8-ounce glasses of low-fat milk each day, combined with the calcium from the rest of a normal diet, is enough to meet the recommended daily requirements for most individuals. Foods fortified with calcium and calcium supplements can assist those who do not consume an adequate amount of calcium-rich foods.
• For many, especially elderly individuals, getting enough vitamin D from sunshine is not practical. These individuals should look to boost their vitamin D levels through diet. Vitamin D is also available in supplements for those unable to get enough through sunshine and diet.
• In addition to meeting recommended guidelines for physical activity (at least 30 minutes a day for adults and 60 minutes for children), specific strength- and weight-bearing activities are critical to building and maintaining bone mass throughout life.
• Individuals should see a health care provider if they have a medical condition or use medications that can affect the skeleton. Women should also see their health care provider if menstrual periods stop for 3 months.

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Introduction

As the evidence presented in the previous chapter makes clear, there is much that individuals can do to promote their own bone health throughout life. This chapter outlines recommendations for diet, physical activity, and other lifestyle practices that can help to achieve that goal. Moreover, the activities and practices suggested in this chapter contribute not only to bone health, but to overall health and vitality. In fact, bone-specific recommendations fit well within an overall program of good nutrition and physical activity that should be followed in order to prevent the onset of many of the major chronic diseases affecting Americans.

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Nutrition

Since many nutrients are important for bone health, it is important to eat a well-balanced diet containing a variety of foods. Following the Dietary Guidelines for Americans (USDA 2000, USDHHS 2000) can help, although attention should be paid to serving sizes. These guidelines urge individuals to eat 6–11 servings of grain foods, 3–5 servings of vegetables, 2–4 servings of fruits, 2–3 servings of dairy or other calcium-rich foods, and 2–3 servings of meat or beans each day. The DASH (Dietary Approaches to Stop Hypertension) Eating Plan (USDHHS 2003), which follows these guidelines, is an example of a well-balanced diet that can be good for bone and heart health, although bone outcomes from DASH have not been specifically tested. The DASH Eating Plan emphasizes fruits, vegetables, low-fat or fat-free dairy foods, whole grains, fish, poultry, and nuts, making it rich in calcium, magnesium, protein, and potassium while also being low in fat, cholesterol, and sodium. For more information about the Dietary Guidelines and the DASH Eating Plan, refer to Appendix C, Resources and Related Links.

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Calcium

The Food and Nutrition Board (FNB) of the Institute of Medicine updated recommended intakes for several nutrients important to the skeleton in 1997, including calcium (IOM 1997). Recommended amounts of calcium, which are shown in Table 7-1, differ by age. These recommendations are meant for healthy people. Those with osteoporosis or other chronic conditions may need more calcium, but unfortunately the calcium requirements for individuals with this disease have not yet been clearly identified (Heaney and Weaver 2003). The highest amount (1,300 mg per day) is recommended for children and adolescents ages 9–18, a period when bones are growing rapidly. Pregnant or lactating women are advised to consume an age-appropriate amount of calcium, as shown in Table 7-1. The Institute of Medicine also defined a safe upper limit of 2,500 mg per day for calcium (IOM 1997). Intakes above 2,500 mg per day may increase the risk of adverse effects in susceptible individuals.

Americans obtain most of their calcium from dairy products. In fact, approximately three 8-ounce glasses of milk each day, combined with the calcium from the rest of a normal diet, is enough to meet the recommended daily requirements for most adults. Lowfat or nonfat versions of dairy products are good choices because they have the full amount of calcium, but help to avoid eating too much fat. Foods that have been fortified with calcium are also good sources of the nutrient. There are many foods that serve as good sources of calcium, including fortified cereal, nonfat milk, and calcium-fortified orange juice from frozen concentrate (Keller et al. 2002). Vegetables also contain calcium, but the amount of calcium absorbed from these sources varies; some, like broccoli and kale, contain calcium that is well absorbed, while others, such as spinach, do not (Weaver et al. 1999). It would be impractical for most people to eat enough vegetables or other low-calcium foods to meet recommended levels if these were the only sources of calcium in the diet. To assist in planning a diet containing adequate levels of calcium, Table 7-2 provides a list of selected food sources of calcium, along with the percent daily value that they contain. These percentages indicate whether a serving of the food contains a high (20 percent or more of the percent daily value) or a low (5 percent or less) amount of a specific nutrient—in this case, calcium. Most individuals can design a diet that is appealing to them (based on their preferences) while also meeting their nutrient needs.

Many individuals, especially non-Whites, suffer from lactose intolerance. These individuals may avoid dairy products, which can result in a low calcium intake unless other good sources of calcium are consumed. Those with lactose intolerance may develop the capability to digest lactose if they slowly build up milk intake over a period of days or weeks so that they develop an intestinal flora capable of digesting milk’s lactose (Suarez et al. 1997). Many lactose-intolerant individuals can tolerate up to one cup of milk twice a day if it is consumed with food (McBean and Miller 1998). In addition, some other calcium-rich dairy products such as cheese and yogurt are usually well tolerated by lactose-intolerant people. Finally, there are a number of calcium-rich foods that do not contain lactose, including lactose-free milk, fortified soy beverage, and fortified juice and cereal. Some tips for those with lactose intolerance are shown in the box below.

The Institute of Medicine recommends that nutrients be obtained from food when possible because they provide a package of nutrients that are good for other tissues besides bones. However, fortified foods and supplements can assist those individuals who do not consume an adequate amount of dairy products or other naturally calcium-rich foods to meet recommended levels of calcium intake. Those who take supplements or consume fortified foods should note that: a) all major forms of calcium (e.g., carbonate, citrate) are absorbed well when taken with meals; b) calcium from supplements or fortified foods is best taken in several small doses (no more than 500–600 mg at one time) (Heaney 1975) throughout the day for better absorption; and c) supplements may differ in their absorbability due to manufacturing practices (IOM 1997). One need not choose the most expensive products on the market, as the cost of supplements of comparable quality can vary fivefold (Heaney et al. 2001). In a recent evaluation of calcium sources, calcium carbonate supplements were found to be the least expensive supplemental source of calcium. Since virtually all calcium sources—food or supplement—reduce the absorption of iron, calcium and iron supplements should be taken at different times.

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Vitamin D

The current recommended intakes of vitamin D are given in Table 7-1. Most individuals need 200 IU per day, although these recommendations are raised to 400 IU per day in those age 50–70, and to 600 IU per day in those over age 70. There are two sources of vitamin D: sunlight and dietary intake.

As discussed in Chapter 6, vitamin D can be made in the skin by being exposed to sunlight. For some individuals, particularly children and others who get enough exposure during warmer months, the sun can provide adequate levels of vitamin D throughout the entire year. For many, however, it is not practical to get adequate levels of vitamin D from exposure to sunshine. These individuals should instead look to boost their vitamin D levels through diet. This is especially true for elderly individuals who have higher vitamin D needs and who may have difficulty getting outside everyday. People with dark skin and those who live in areas with heavy air pollution may also find it more practical to obtain most or all of their vitamin D from diet, since they need longer periods of sun exposure to get adequate levels of vitamin D. Table 7-4 gives the vitamin D content of several foods, although the most common source is fortified milk. One cup of fortified milk contains 100 IU vitamin D, half of the recommended intake for individuals under age 50. Since vitamin D-fortified milk is not used when making cheese, ice cream, or most yogurts, many other dairy foods are not good sources of vitamin D. Other good dietary sources of vitamin D include fatty fish and vitamin D-fortified orange juice. The best way to know whether a dairy food contains vitamin D is to check the nutrition label.

Vitamin D is also available in dietary supplements. While few supplements contain vitamin D alone, many calcium supplements also contain vitamin D. Multivitamin supplements contain up to 400 IU of vitamin D. The amount of vitamin D in a single dose of many calcium and multivitamin supplements may not be sufficient to meet the recommended levels, especially for people over age 70 who need 600 IU per day. To make sure that the recommended amount of vitamin D is consumed as shown in Table 7-1, check the nutrition label on the supplement for the amount of vitamin D per dose, and, if necessary, supplement vitamin D intake through other sources. However, because vitamin D can have negative effects if taken in very high doses, it is also important to avoid consuming more vitamin D than the tolerable upper level of 2,000 IU per day. Larger doses can initially be given to patients who are deficient as a means of replenishing the stores of vitamin D in the body.

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Other Nutrients Important to Bone

As shown in Table 7-1, the Institute of Medicine recently provided recommended intakes for other bone-related nutrients, including phosphorus and magnesium (IOM 1997). Most Americans consume adequate quantities of phosphorus through their regular intake of meats, cereals, milk, and processed foods. While some beverages such as soft drinks also contain phosphorus, they are not a preferred source of phosphorus because they may displace calcium-rich beverages like milk (Whiting et al. 2001).

Magnesium intakes may be suboptimal in those who do not eat enough green leafy vegetables, whole grains, nuts, and dairy products. Fortunately, most diets contain adequate levels of other bone-related micronutrients, such as vitamins K and C, copper, manganese, zinc, and iron, to promote bone health.

Some dietary components may potentially have negative effects on bone health, especially if calcium intakes are not adequate. For example, high levels of sodium or caffeine intake can increase calcium excretion in the urine. The effects of these factors can be overcome by increasing the amount of calcium in the diet (Fitzpatrick and Heaney 2003). Studies have linked excessive amounts of phosphorus to altered calcium metabolism, but it appears that the typical level of phosphorus consumed by most individuals in the United States should not negatively affect bone health (IOM 1997). Excessive amounts of preformed vitamin A (e.g., retinol) can also have negative effects on bone, so individuals should not consume more than the recommended dietary allowance for this vitamin (IOM 2000). The vitamin A precursor (beta carotene) found in many fruits and vegetables does not have negative effects on bone, however.

Table 7-5 provides additional information on other nutrients that affect bone, their recommended dietary allowances, and common dietary sources of these nutrients.

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Physical Activity

The foundation of a good physical activity regimen involves at least 30 minutes (adults) or 60 minutes (children) of moderate physical activity every day. This regimen can and should involve a variety of activities. Some can be routine activities like walking or gardening. Others may occur more infrequently and differ from day to day and week to week, such as dancing, aerobic classes, biking, swimming, tennis, golf, or hiking. However, it is clear from the evidence presented in Chapter 6 that physical activity to specifically benefit bone health should involve loading (stressing) the skeleton. As a result, weight-bearing activities such as walking should be included in an optimal physical activity regimen to benefit the musculoskeletal system. Moreover, the evidence suggests that the most beneficial physical activity regimens for bone health include strength-training or resistance-training activities. These activities place levels of loading on bone that are beyond those seen in everyday activities; examples include jumping for the lower limbs and weight lifting or resistance training for the lower and upper skeleton. Finally, while a focus on activities that build or maintain bone strength is appropriate and necessary, many older individuals will remain at high risk of fracture. For these individuals, balance training can provide the added benefit of helping to prevent potentially injurious falls.

As noted in Chapter 6, the evidence does not lead to a specific set of exercises or practices but rather a set of principles that can be applied and varied according to the age and current physical condition of an individual. Many of these principles have been reviewed by expert panels of the American College of Sports Medicine (ACSM) (Kraemer et al. 2002, ACSM 1998a, ACSM 1998b) and they lead to the following suggestions for the frequency, intensity, length, and type of physical activity regimens to benefit bone health for individuals of all ages:

• Since continued physical activity provides a positive stimulus for bone, muscle, and other aspects of health, a lifelong commitment to physical activity and exercise is critical.
• Ending a physical activity regimen will result in bone mass returning to the level that existed before the activity began. Since repetitive programs of physical activity may be discontinued due to lack of motivation or interest, variety and creativity are important if physical activity is to be continued over the long term.
• Physical activity will only affect bone at the skeletal sites that are stressed (or loaded) by the activity. In other words, physical activity programs do not necessarily benefit the whole skeleton, although any type of activity provides more benefit to bone than does no activity at all.
• For bone gain to occur, the stimulus must be greater than that which the bone usually experiences. Static loads applied continuously (such as standing) do not promote increased bone mass.
• Complete lack of activity, such as periods of immobility, causes bone loss. When it is not possible to avoid immobility (e.g., bed rest during sickness), even brief daily weight-bearing movements can help to reduce bone loss.
• General physical activity every day and some weight-bearing, strength-building, and balance-enhancing activities 2 or more times a week are generally effective for promoting bone health for most persons.
• Any activity that imparts impact (such as jumping or skipping) may increase bone mass more than will low- and moderate-intensity, endurance-type activities, such as brisk walking. However, endurance activities may still play an important role in skeletal health by increasing muscle mass and strength, balance, and coordination, and they may also help prevent falls in the elderly. Endurance activity is also very important for other aspects of health, such as helping to prevent obesity, diabetes, or cardiovascular disease.
• Load-bearing physical activities such as jumping need not be engaged in for long periods of time to provide benefits to skeletal health. In fact, 5–10 minutes daily may suffice. Most adults should begin with weight-bearing exercise and gradually add some skipping and jumping activity. Longer periods (30–45 minutes) may be needed for weight training or walking/jogging. Those who have been inactive should work up to this amount of time gradually using a progressive program, e.g., start with shorter times and easier activities (light weights or walking) and then increase time or intensity slowly (by no more than 10 percent each week) in order to avoid injury.
• Physical activities that include a variety of loading patterns (such as strength training or aerobic classes) may promote increased bone mass more than do activities that involve normal or regular loading patterns (such as running).

These fundamental principles can be used to develop age-specific regimens, as outlined in the sections that follow.

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Physical Activity for Children and Adolescents

For children over age 8 and adolescents, a bone-healthy program of physical activity could include the following:

• At least 60 minutes of moderate intensity, continuous activity on most days, preferably daily. This level of activity can help achieve a healthy body weight and lower the risk of other diseases such as cardiovascular disease and diabetes (USDHHS 1996, USDA 2000, USDHHS 2000, IOM 2002).
• Inclusion of weight-bearing and short, intense impact activities such as basketball, gymnastics, and jumping as part of this regular activity program.
• Performance of weight-bearing activities that increase muscle strength, such as running, hopping, or skipping. The best activities work all muscle groups. Examples include gymnastics, basketball, volleyball, bicycling, and soccer. Swimming, while highly beneficial to many aspects of health, is not a weight-bearing activity and thus does not contribute to increased bone mass.

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Physical Activity for Adults

Adults should strive to get at least 30 minutes of physical activity on most days, preferably daily (USDHHS 1996, USDA 2000, USDHHS 2000, IOM 2002). As part of that regular physical activity program, the following can help enhance bone health:

• For those individuals who can tolerate impact activities, a simple, 10-minute program of physical activity that incorporates 50 3-inch (8-centimeter) jumps per day.
• A progressive program of weight training that uses all muscle groups, with the amount of weight lifted increased gradually over time.
• A jogging or stair-climbing program for those who cannot tolerate higher impact physical activity.
• Active recreational activities such as tennis, hiking, or basketball.

In addition, it is advisable for adults to try to find ways to add extra weight-bearing exercise into everyday activities. For example, consider parking farther away in the parking lot or taking the stairs instead of the elevator.

General recommendations for physical activity in adults are shown in the pyramid in Figure 7-2, with the base of the pyramid being 30 minutes or more of moderate physical activity on most, preferably all, days of the week. It is also recommended that weight-bearing exercises and strength and balance training be added as a part of regular physical activity (Nelson 2002, Seguin and Nelson 2003). Lifestyle activities such as walking, gardening, and raking leaves can also be a valuable part of regular physical activity (USDHHS 1996).

It is important to begin any physical activity program slowly and to consider previous activity levels. Those who have been inactive should begin with 5–10 minutes of activity per day and a pre-exercise evaluation by a physician may be advised. Those who are more fit can increase physical activity levels to 20–30 minutes of moderate activity at a higher heart rate (60–85 percent of maximum heart rate). Generally, it is advisable to increase activity levels by no more than 10 percent each week to avoid injury. For example, those who begin with 15 minutes per day can progress to 17 minutes the second week, and so on.

Finally, adults should consult a physician or physical therapist if orthopedic conditions like arthritis, functional limitations, or other medical conditions make these physical activity guidelines difficult or unsafe to follow.

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Physical Activity for Older Adults

Most elderly individuals should strongly consider engaging in regular physical activity. Physical activity is the only single therapy that can simultaneously improve muscle mass, muscle strength, balance, and bone strength. As a result, it may decrease the risk of fractures, in part by reducing the risk of falling. In fact, fall-risk reduction may be the biggest benefit of physical activity for the elderly.

The following guidelines should be used to maximize the potential fall prevention benefits of physical activity in the elderly:

• Physical activity needs to be of sufficient intensity to improve muscle strength, since poor muscle strength is a known risk factor for falls. Strength or resistance training is best for building muscle, but even aerobic endurance activity can yield some improvements in muscle strength.
• Improving balance can be an important component of any physical activity program designed to decrease falls. This program may include balance training exercises or a movement activity such as Tai Chi. Any activity that requires weight bearing and challenges the postural system can improve balance and potentially help reduce falls.
• Physical activity must be performed on average 3 times per week for 30–45 minutes per session for at least three months for strength and balance benefits to be realized, and it must be continued if benefits are to be maintained.
• Those who suffer a fall that requires a visit to a health care provider or an emergency room should ask for a fall risk assessment that includes a program of physical activity. Physical activity is most effective if delivered as a part of a comprehensive fall prevention program (see Chapter 6).

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Physical Activity for Those With Fragility Fractures

Individuals who have already experienced osteoporotic fractures should avoid certain types of physical activities and exercises. For example, those who have had vertebral fractures may need to avoid activities that flex the spine. For more information about appropriate physical activity after osteoporotic fracture, see Chapter 9, “Rehabilitation of Osteoporotic Fractures.”

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Fall Prevention

It is no surprise that falls are often the “precipitating” event that leads to a fracture in individuals with low bone mineral density (BMD), and that therefore preventing these falls can reduce the risk of fracture. Falls are a major contributor to hip fractures and are also associated with a significantly increased risk of many other fractures, including spine, wrist, pelvis, and upper arm. Since falls are usually caused by multiple factors, successful prevention strategies should involve multiple components. The benefit of physical activity in reducing the risk of falls was discussed in the previous section. There is more that can be done to reduce the chances of a fall and to minimize the impact of any fall that does occur. Guidelines issued by the American Geriatrics Society, British Geriatrics Society, and American Academy of Orthopedic Surgeons panel on falls prevention include the following recommendations for older persons (AGS et al. 2001):

• Inform health care providers about any fall, even those that do not result in serious injury. Providers should ask their older patients at least once a year about falls.
• Those who have fallen one or more times should ask their health care providers about the need for a test of their balance and ability to walk.
• Those who need medical attention after a fall or who have fallen several times in the past year should have a fall evaluation. This evaluation should include taking a history related to the circumstances of the fall and performing an examination of vision, balance, walking, muscle strength, heart function, and blood pressure. A specialist, such as a geriatrician, may be needed for this evaluation.
• Health care providers should consider prescribing a program of physical activity and balance training, with an emphasis on those activities that may help reduce risk of falling. Patients can also seek these programs on their own.
• Patients should ask their health care providers to review any medications they are taking (including over-the-counter ones) at least once per year. This step can help to avoid various medication-related problems that commonly lead to falls, such as drug-drug interactions and unnecessarily high doses of certain drugs.
• Vision should be checked annually.
• Individuals should review their homes for possible hazards that could cause a fall, such as loose rugs, poor lighting, electrical cords, or lack of handrails in the tub/shower.
• Individuals should be careful when using step ladders, making sure to use ladders that are stable and have a handrail.

Finally, as discussed in Chapter 6, use of hip protectors or hip pads may help reduce the risk of fractures for persons living in institutionalized care settings.

A good source for tips on how to prevent falls is “The Tool Kit to Prevent Senior Falls,” developed by the Injury Center at the Centers for Disease Control and Prevention (CDC). This kit contains “What You Can Do to Prevent Falls,” an informational brochure, and “Check for Safety,” a home safety checklist designed to help older adults and caregivers identify and correct home hazards. It also contains four fact sheets and other relevant materials, and is available at http://www.cdc.gov/injury.

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Other Aspects of a Bone-Healthy Lifestyle

In addition to having a healthy diet, sufficient physical activity, and avoiding falls, there are some other bone-healthy behaviors that can help protect the skeleton throughout life:

• Maintain a healthy body weight.
• Avoid smoking.
• If one drinks alcoholic beverages, do so in moderation (i.e., one drink per day for women and two drinks per day for men).
• For women, see a health care provider if menstrual periods stop for three months.
• For those who have a medical condition or who use medications that can affect the skeleton (listed in Tables 3-1 and 3-2 in Chapter 3), talk to a health care provider about ways to safeguard the skeleton.

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Summary

Following the suggestions outlined in this chapter on diet, physical activity, and other lifestyle behaviors can help ensure good skeletal health throughout life. For more specific information on how to adopt a bone-healthy lifestyle, see the resources listed in Appendix C. It is never too late for individuals, even frail elders, to start following a bone-healthy lifestyle.

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Key Questions for Future Research

Research questions related to lifestyle approaches that promote bone health are included in the questions identified in Chapter 6 on page 141.

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References

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Published: October 14, 2004

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