Bone Health

Bone Health

Andrew Siegel, MD   Blog #118

Our bones are our foundation, the framework that supports the rest of our body.  If our infrastructure is “crumbling,” other organs and tissues that depend on intact structural support can be profoundly affected.  In other words, if our foundation and framework are shoddily constructed, the rest of our structures and functions are likely to be adversely impacted.

“Rickety” is a descriptive adjective meaning shaky, run down, and dilapidated.  It is derived from the disease rickets, a “softening” of the bones due to Vitamin D issues that can lead to fractures and deformities, typically seen in children suffering from malnutrition.  It is important to avoid the development of rickety bones—we do not want to be built of a “house of cards,” as we function best if our bones are “steely.”

A fundamental problem in terms of bone health and vigor is that most people do not consider their bone health early in life.  Unfortunately, it only becomes a matter of concern at a time in which it is getting late in the game to protect against loss of bone strength and fractures. The time to focus on bone health is during childhood when the achievement of bone integrity and strength begins.  This bone formative process continues through adolescence, when the body builds the lion’s share of bone mass, and peaks in our early 20’s. One-quarter of bone mass is obtained within the two-year window of time around puberty; as much bone is gained in this two-year period as is typically lost in the 30-year interval between ages 50-80.

Since children, understandably so, are not likely to consider their bone health, as responsible parents we must educate our kids and be the overseers of their diets, physical activities and sun exposure—all of which can positively contribute to healthy bone development—as well as lead by example. Helping them achieve the goal of bone health during adolescence is an investment in personal health that will pay dividends later in life, helping to prevent bone thinning and the potential for fractures.   It is important to direct our children away from computer games, television and other sedentary activities and motivate them towards the outdoors to participate in a variety of physical activities. It is equally important to encourage them to have a nutritionally sound diet rich in calcium-containing foods including dairy sources such as milk, yogurt and cheese; non-dairy sources including vegetables such as Chinese cabbage, kale, broccoli and spinach; seafood sources such as salmon and sardines; and calcium-fortified sources such as cereals, tofu and fruit juices.  It is equally as important to ensure sufficient vitamin intake.  Vitamin D is necessary in order to absorb and utilize dietary calcium; a brief amount of sunlight exposure on a daily basis is generally sufficient to ensure adequate levels of vitamin D. Children can kill two birds with one stone by participating in athletic activities outside in the sunlight.

In terms of key factors determining bone health, genetics looms large.  In other words, if bone thinning tends to run in your family, you will have a greater likelihood of suffering the same fate.  Like so many of our physical attributes, bone strength and integrity have a strong hereditary basis and there is not a thing that we can do about the genes that we inherit. Additionally, age and gender are important elements.  There is a gradual but insidious loss of bone mass that correlates with the aging process, and the older we are, the greater the likelihood for osteopenia, the medical term for bone loss. Osteoporosis is the medical term applied to severe bone loss with great risk for fractures.  Women are at much higher risk for such bone thinning and wasting processes than men.

Although genetics, age, and gender are factors beyond our control, exercise and intake of bone-building nutrients including calcium and vitamin D are modifiable factors that we have some real influence over. Thin people tend to have greater issues with osteopenia than heavy people.  One of the few advantages of being overweight is that it requires extra anti-gravitational weight-bearing effort to carry around that excess poundage; this exertion against the force of gravity helps to mineralize and fortify bones.

The male and female sex hormones, testosterone and estrogen respectively, play a health role that goes way beyond sexuality.  Both of these hormones promote bone health and mineralization. After menopause, with the precipitous drop in estrogen, there is often an acceleration of bone loss. Men often experience a gradual drop in testosterone levels correlating with the aging process.  A healthy testosterone level is correlated with bone health and low levels of testosterone are linked with osteopenia.   Men who are on medication to purposefully lower testosterone—most typically used for the management of prostate cancer—experience an accelerated loss of bone mass, akin to women at the time of menopause.  Reasons that males experience bone loss at a less accelerated rate than females include the fact that men in general weigh more than women, and thus by virtue of the fact that they have to carry around extra weight, they keep their bones mineralized; additionally, the variable changes in testosterone with aging that men experience are much more minor as opposed to the major precipitous decline in estrogen at menopause in women.

Our bones demand physical activity in order to stay well mineralized.   When our bodies are kept in a sedentary state—for example when one’s arm is in a cast because of a fracture, or when one is immobilized by a severe injury and is at bed rest—there is a rapid demineralization and thinning of our bones.  Spinal cord injured patients who are paralyzed undergo a very rapid demineralization. Astronauts who spend time in zero gravity experience a remarkably fast demineralization and run the risk not only of thinning bones—as does anybody with rapid demineralization— but also of developing kidney stones that result from the calcium mobilized from the bones.

In general, the more active the individual, the greater the bone mineral density (BMD) and the less risk for fracture.  Most any physical exercise is healthy for our bones, but there are certain exercises that are better to achieve the endpoint of achieving bone mineralization and vigor. BMD is greater in sprinters, ball sport athletes and gymnasts than in endurance sports athletes including walkers, runners, swimmers and cyclists.  Bone mineralization is promoted by stresses placed upon the bones, rest periods, and variety, as opposed to repetitive, monotonous movements.  Aerobic ball sports activities provide highly effective variable stresses on our bones that work against gravity and provide periods of rest; these include tennis, squash, football, soccer, basketball, hockey, field hockey, lacrosse, dancing, and gymnastics.   Additionally, weight training and any activity that uses resistance equipment can be a highly effective means of promoting bone mineralization.  Training that necessitates straining, versatile movements, and a high peak force is more effective in terms of bone mineralization than training with a large number of low-force repetitions. It seems that just as ones body requires a variety of different and variable nutrients to maintain its health, so ones bones require a variety of different exercises, movements, and stresses to maintain their health

Runners and swimmers have the lowest bone densities among athletes. Some studies have even shown that participants in endurance and non-weight-bearing sports have bones that are less robust and at a greater risk of fracture than the population of sedentary and inactive people.  In terms of increasing bone mineral density, when running, swimming, and cycling, it is best to shake it up and do interval training at variable speeds, intensities, and durations and not maintain a monotonous motion, since repetitive unvarying stress can actually demineralize bone and is thus not a productive means of increasing bone fortitude.

Bone mineralization is a dynamic process as opposed to a static process.  In other words, our bones are not fixed in composition like the framing and foundation of our homes.  Our bones are constantly being remodeled, restructured and refashioned in accordance with the building blocks available and in an adaptive response to biomechanical forces including gravity and musculo-skeletal stresses.

The concept of  “energy availability” is important in terms of understanding bone building versus bone destruction.  Energy availability is defined as the amount of energy taken in while exercising minus the amount expended, divided by lean body mass (consisting of bone and muscle).  Energy availability is the net amount of energy available to support all the body’s functions including new bone formation, a process that requires energy.  Low energy availability will occur if there is insufficient intake of calories, excessive burning of calories, or a combination of both.  Endurance athletes—including long-distance runners and cyclists—can burn so many calories that there is not sufficient energy remaining to fuel the dynamic process of maintaining bone health.  When there is low energy availability, the consequence can be stress fractures, fractures due to repeated stresses on a weight-bearing bone.

Bottom Line: Bone health has its critical beginnings in childhood, then continues (at a slower pace) into adulthood.  Key factors contributing to maximal bone health are proper nutrition, varied and continued physical activity, vitamin intake, and exposure to sunlight.  It is never too early to address—and take the necessary measures—to ensure the life-long health of the body’s vital skeletal framework

Reference:  “To Ensure Bone Health, Start Early,” article in New York Times by Jane E Brody, August 5, 2013

Andrew Siegel, M.D.

Author of Promiscuous Eating: Understanding and Ending Our Self-Destructive Relationship with Food:

Available on Amazon in Kindle edition

Author of: Male Pelvic Fitness: Optimizing Sexual and Urinary Health, in press and will be available in e-book and paperback formats in the Autumn 2013.

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