If you had to let one thing go in life, which would it be: muscle or bone? Hard choice to make, isn’t it? These two tissues work in sync throughout the body and are what allow us to keep our form and function. Muscles in particular provide the force for movement of body parts, and your muscular system is connected to every other system of the body, including your skeletal system (hence the term musculoskeletal system). Muscles play a crucial role in the development of bones and the maintenance of their integrity, and the calcium you absorb with the help of vitamin D in your intestines is also essential for nerve-impulse and muscular functions. Bones are not freewheeling parts. If they weren’t attached to your skeletal muscles, with a shared interest in having ample supplies of vitamin D and calcium available, you wouldn’t be able to walk, dance, talk, or eat. Your musculoskeletal system is as much part of your survival as is the air you breathe.
So it’s no surprise that the intertwining of these two tissues means that what can damage one may also damage the other. Several cross-sectional studies dating years back by Dr. Heike Bischoff-Ferrari and others have shown that a low 25-vitamin D level is related to lower muscle strength, increased body sway, falls, and disability in older men and women. In April of 2000 Dr. Anu Prabhala and his colleagues at SUNY Buffalo reported on the treatment of five patients confined to wheelchairs with severe weakness and fatigue. Blood tests revealed that all suffered from severe vitamin D deficiency. The patients received 50,000
IU of vitamin D per week, and all became mobile within six weeks. Their results were published in Archives of Internal Medicine.
Newer evidence further confirms that low levels of vitamin D may be a factor in loss of muscle mass and muscle strength, which we saw at the beginning of this chapter is among the more defining consequences to growing older and weaker. One population-based study from the Netherlands reported that higher levels of circulating 25-vitamin D in both active and sedentary adults sixty years or older were associated with better musculoskeletal function in the legs and lower odds of decline in physical performance as compared to counterparts with lower levels of 25-vitamin D.
Being able to have full function of your legs—not to mention other body parts
—later in life can make a significant difference in the ability to stay active and maintain a certain quality of life—which, in turn, affects a person’s capacity to continue to maintain and build these lean tissues. Both muscle and bone require the good kind of physical stress that comes with exercise and strength training (weight-bearing exercise) that supports the health of these special tissues. I’ll go into more detail about that on page 211.
Recall our two ten-year-old girls from chapter 1 and how, hypothetically speaking, each may face a different fate based on her environment and level of vitamin D. I mentioned that the equatorial girl may be able to jump higher and with more force than her northern counterpart. Why? Because studies have also shown that levels of 25-vitamin D correlate with muscle power and force. One study in particular that was reported in 2009 looked at adolescent girls and revealed that vitamin D is positively related to muscle power, force, velocity, and jump height. This finding alerted researchers to continue investigating this area, because a maturing adolescent with suboptimal muscular force may have long-term consequences in full bone development.
Later in this book, when we get to the how-to’s of maintaining optimal levels of vitamin D, I’ll elaborate on why physical exercise is so essential to the health and maintenance of your bones and muscles. Adequate vitamin D and calcium intake, along with exercises that stress your musculoskeletal system, constitute the dynamic trio. This is true for both older adults and prepubescent children, whose bone development can be positively influenced by physical activity.
Studies continue to come out addressing the perfect storm of not enough vitamin D, not enough calcium, and not enough exercise. Not only does being indoors attached to the computer and television keep children out of the vitamin D-
making rays of the sun, but it also keeps them from doing the essential weight-bearing exercises, such as running and jumping, that encourage young bones to grow denser and stronger. What’s more, some studies suggest that children and teens today get 20 percent less calcium than is minimally recommended. The culprit? Too much processed food and soda.
Unfortunately, with the recommended daily intake of vitamin D unchanged for over fifty years for children and adults up to fifty years of age, and with our problem of childhood obesity deepening, our youngest generation may be the first generation in the history of humankind to suffer the most health consequences as a result of being deprived of adequate vitamin D. There is no excuse for not getting enough vitamin D when it’s freely available from the sun, but we all know that there are plenty of excuses to use in staying out of the sun and forgetting what we’re missing. Until it’s too late.