By Nanci S. Guest
When we talk about bone health, most of us associate osteoporosis with our Grandmothers. In reality, taking care of our bones is not just a concern for the elderly and should start at an early age. Lack of physical activity, a poor diet and inadequate calcium intake are prevalent among today's children. Unfortunately, these early bad habits can negatively impact long-term bone health, increase the risk of premature osteoporosis and contribute to the growing osteoporosis epidemic. It is now estimated that osteoporosis affects 1 in 3 women over 50 years of age (1). Women in general have a lower bone mass and are at a greater risk for osteoporosis (even though the gap narrows when men and women are close to 70 years old). Whether you are working with young girls, adults or elderly women, understanding how exercise, nutrition and lifestyle can influence bone health is an important area of understanding and application.
Bone Health Over the Life Span
Childhood bone growth is gradual and is associated with a child's overall development. At the onset of puberty, rapid bone growth occurs. After a female's menarche, the additional stimulus of estrogen secreted from the developing ovaries results in the skeleton retaining about 150-350 mg/day of calcium. Calcium absorption efficiency is high during this three to five year maturation period, but adequate total dietary calcium is critical to sustain these high retention levels. Sufficient levels of calcium should be available during the bone building years so that the attainment of the full genetic expression of peak skeletal mass is possible. The opportunity to build bone greatly diminishes in the late teens and up to 95% of the peak bone mass is achieved by age 20. The remaining 5% can be attained up until the early 30's. Children and teens can maximize their peak bone mass and take advantage of this window of opportunity by consuming adequate calcium and vitamin D, as well as taking part in regular weight-bearing physical activity. Calcium, vitamin D and exercise work synergistically to stimulate calcium deposition into the skeleton.
In adulthood, bone mass begins to decline at a very low rate. Prolonging the rate of loss is important to ensure a greater bone density at the time of menopause when bone loss is inevitable and greatly accelerated. A woman can lose up to 20% of her bone mass in the 5 years following menopause and therefore, maximizing peak bone mass potential and maintaining healthy bones during adulthood is critical to the prevention of premature osteoporosis in later years. Osteoporosis is not part of normal aging and a long-term effort toward prevention is needed to educate younger generations about the importance of bone health.
Nutrition and Bone Health
Calcium: Calcium is one of the best life-long defenses against osteoporosis. Calcium is primarily stored in the bones and if there is not enough calcium in the blood and soft tissues, the body will replenish the supply by robbing it from your bones. This slow depletion of calcium from the bones causes the bones to weaken and increases the potential for stress fractures and osteoporosis. The best way to obtain adequate calcium is to eat ample amounts of calcium-rich food from childhood, through menopause and beyond. Ensuring enough calcium in the diet may be difficult (check your status below) and a calcium supplement may be necessary.
Vitamin D: Vitamin D is needed for the absorption of calcium and is just as important for healthy bones and Vitamin D can be found in foods. In addition, your skin produces Vitamin D from sunlight. Approximately 10 minutes of sunlight per day on bare forearms is required for the process. Many older people require a Vitamin D supplement.
Protein: Protein is also necessary for healthy bones. Adequate protein, but not excessive intakes from a variety of sources including both animal & plant sources seems to be the best approach toward healthy bones.
· Fruits & Vegetables: Recent and exciting research has found that a high intake of fruits and vegetables, which are alkali-forming foods, decrease markers for bone turnover (less breakdown). This is a very significant finding and suggests that a high consumption of alkali-forming foods may benefit bone health (2).
Alcohol: There is continuing data (3) that provide support for the beneficial effect of moderate alcohol intake on bone mass. However, more than 3-4 drinks per week can have detrimental effects.
Caffeine: Caffeine may (3) or may not (4) affect bone health and should be limited or used in moderation. Adequate calcium intake with moderate caffeine consumption appears to be the best approach for individuals who consume caffeine. For example, drinking a latte is a better option than black coffee because the milk in a latte will provide an excess of calcium to counter any calcium losses due to the caffeine.
Table 1. Calcium and Vitamin D Requirements
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* Table 3. Food Sources of Vitamin D
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Tips for Increasing the Dietary Intake of Calcium:
Breakfast
· Mix a tablespoon or two of crunchy cereal into a container of low fat yogurt
· Use skim milk instead of water when mixing up hot cereal
· Try a low fat yogurt drink or carton of milk for an on-the-go meal
· Drink a glass of calcium fortified orange juice daily
· Make a smoothie with fruit, low fat yogurt, milk and ice
Lunch
· Opt for a carton of low fat or skim milk rather than soda
· Add a slice of low fat cheese to sandwiches
· Top a steaming baked potato with low fat yogurt or cottage cheese
· Sprinkle low fat cheese on top of soup
· Eat broccoli florets with a sour cream or yogurt based dip
· Use skim milk instead of water when preparing soups
Dinner
· Order pizza with low fat mozzarella and lots of green vegetables
· Top pasta and salads with low fat cottage cheese or part-skim ricotta
· Steam up collard or turnip greens and top with lemon or saute in olive oil
· Make low fat macaroni and cheese – in addition, add broccoli
· Marinate tofu and grill or stir fly
· Finish off with low fat frozen yogurt
Exercise and Bone Health
The term weight-bearing exercise often confuses people. The National Osteoporosis Foundation defines weight-bearing as exercise in which bones and muscles work against gravity as the feet and legs bear the body's weight. Examples of weight bearing activities include walking, jogging, stair climbing, dancing, racquet sports and weight training. However, over exercising can actually decrease bone density and for women, loss of menses may be a signal that a female may be participating in too much physical activity.
Resistance training is also an excellent way to help increase or maintain bone density due to the stress placed upon the bone as the muscles shorten during contraction. The contraction causes a slight "bending" of the bone where the muscle is attached and stimulates increases in bone density. As well, resistance training strengthens back muscles, which can help to improve and maintain posture of an osteoporotic spine that has rounded over. A qualified profession who works with special populations will be able to correctly diagnose a spinal irregularity.
Osteoporosis
Osteoporosis is defined as a loss of calcium from the skeleton resulting in weaker bones that are more susceptible to fracture, or compression in the spinal vertebrae. Osteoporosis causes an imbalance in the cycle of bone re-building and like many tissues in the body, bone is continually removed and re-built. Osteoporosis occurs when the balance of removal and renewal shift towards removal, and the bones lose their density. Listed below are risk factors for osteoporosis that can and cannot be modified. Fortunately, diet and exercise are factors that can be modified and together create healthy bones.
Risk Factors for Osteoporosis
Factors that CANNOT be modified:
· Caucasian or Asian ancestry
· Female gender
· Family history of osteoporosis
· Early menopause
· Small body (skeletal) frame
· Advanced age
Factors that CAN be modified:
· A poorly balanced diet
· Low dietary intake of calcium and vitamin D
· Smoking
· Lack of exercise
· Excessive alcohol
· Certain medications
Other Factors Affecting Bone Health: Fact or Fiction
1. Drinking soda pop weakens bones: Up until 2000, there was a strong theory stating that the phosphoric acid (5) or the carbonation in soft drinks was depleting the calcium in children's bones. After more research, it has been concluded that it is not the actual ingredients in soft drinks that weaken bones, but the replacement of milk from a child's diet with other beverages such as soda pop. Therefore, the decreased level of milk intake is the concern.
2. Caffeine weakens bones: The effect of caffeine consumption on indices of bone health, both in terms of bone mass and fracture risk, remains inconclusive (3,4). There is research that supports that caffeine consumption either has no effect on bone health or has a negative effect - with the most harmful outcomes resulting from a combination of high caffeine intake coupled with low calcium intake. Therefore, adequate calcium intake combined moderate caffeine consumption appears to be an acceptable conclusion at this point in time.
3. Severe dieting can weaken bones: It is true that severe dieting can weaken bones. Not only do severe dieters consume too little calcium, restricted caloric intake in females results in very low body weight or disordered eating behaviors. These behaviors can cause a female to have irregular periods or no periods at all. Irregular and the non-occurrence of periods is extremely damaging to bone health. In the short term, severe dieters have an increased risk for stress fractures and in extreme eating disorders cases, premature osteoporosis can occur.
4. Excess animal protein leads to bone loss: Excess protein in the diet can cause bones to leach calcium. However, this type of excess is rare. Moderation and a balanced diet is key and a recent study made claims against the intake of animal protein (6), but the study has since been criticized for poor design. Interestingly, a more recent study (7) showed that vegetable protein was linked to low bone density. All in all, adequate protein from a variety of sources seems to be the best approach for a healthy diet. Further, if a higher protein diet is matched with high calcium intake, the increased protein intake most likely will not adversely affect bone health.
Lifting weights is good for your bones:
Lifting weights is definitely important for healthy bones. The stress placed on the bone when lifting weights is a valuable stimulus. The stimulus signals the deposition of more calcium into the bones and increases the bone's structural integrity and density.
Should calcium pills be taken in split does?
If you are taking more than 500 mg of a calcium supplement to meet your daily requirements, the dose should be split, and taken in the morning and evening. The body can only absorb a maximum of about 500 mg at one time. So for example; if your goal is 1000 mg/day, and your diet includes 300 mg a day, then 700 mg must be supplemented. The supplement would then be split into two 350 mg doses, morning and evening.
In Summary:
Positive Tips for Healthy Bones at Any Age
· Eat a well balanced diet with ample fruits, vegetables and adequate, but not excessive amounts of protein
· Vegetarians or individuals following a special diet should consult a
nutritionist about food sources of calcium and the possible need for supplements
· Ensure adequate calcium and vitamin D in the diet
· Limit alcohol and caffeinated beverages
· Don't use tobacco products
· Participate in regular weight bearing exercise such as walking, dancing, sports
· Participate in resistance training exercise (weight lifting, power yoga, etc.) to stress the bones and increase bone density
References
1. National Osteoporosis Foundation. : America 's Bone Health: The State of Osteoporosis and Low Bone Mass in Our Nation. 2001 report.
2. New SA, Robins SP, Campbell MK, et al. Dietary influences on bone mass and bone metabolism: further evidence of a positive link between fruit and vegetable consumption and bone health? Am J Clin Nutr. 2000;71:142-151.
3. Ilich JZ, Brownbill RA. More evidence for the beneficial effects of moderate alcohol intake and adverse effects of caffeine consumption on bone mass in postmenopausal women.J Bone Miner Res. 2001;16(suppl 1):S273.
4. Homan MC, McGovern PG, Bowman PJ, et al. Caffeine consumption, rates of hip bone loss and risk of hip fracture. J Bone Miner Res. 2001;16(suppl 1):S386.
5. Heaney et al. American Journal of Clinical Nutrition. 1999, vol. 69, pp.727 – 36
6. Sellmeyer, D.E., et al. A high ratio of dietary animal to vegetable protein increases the rate of bone loss and the risk of fracture in postmenopausal women. American Journal of Clinical Nutrition 73(January):118. 2001.
7. Barrett-Connor, E et al. Animal protein consumption associated with bone density in elderly women. Am J Epidemiol 2002;155:636-644.