The Need for Calcium

“The harder the demand placed upon the structure, the stronger the foundation must be.”

          Making healthy food choices involves knowing which foods to eat when and knowing the best way to get the vitamins and minerals our bodies need to function optimally. Our bones are an extremely important part of our body since they protect our organs, manufacture red blood cells, provide a place for muscles to connect, and provide the framework for our bodies.

           

            As was discussed in a previous post, Dancers and Bone Health, bone tissue is constantly being renewed until the age of about 35 when bone building, or modeling, begins to slow down.  At that time, our bodies have to depend upon the bone tissue that was amassed during the adolescent years to keep the bones healthy and strong.

            Studies have found that dancers’ bone mass measurements, or bone mineral density values, are below what is expected and can cause stress fractures.  This connection is discussed in detail in the post Why Dancers May Be At Risk for Stress Fractures and Osteoporosis.  In addition to engaging in weight bearing activity to increase bone mineral density, dancers need to be concerned about the amount of calcium they ingest.

            Calcium does many jobs in the body.  It aids in muscle contractions, sending messages throughout the nervous system, and regulating hormone and enzyme levels, but its main job is to develop strong bones.  Most dancers do not get enough calcium simply because they restrict caloric intake, and the foods that contain the most concentrated amounts of calcium tend to be high in calories.

            During the teen years, calcium intake should be about 1300 mg/day, while adults should ingest between 1000 and 1300 mg/day.  An important thing to remember is that calcium absorption is aided by vitamin D.  Sunlight is the best source of vitamin D, but, unfortunately, our necessary use of sunblock prevents us from absorbing it.

            The best way to meet our calcium and vitamin D needs is through dairy products like low-fat milk, yogurt, or cheese.  A 1996 study found that calcium fortified orange and apple juices are also good sources of readily absorbable calcium. (1)

            Almond milk is a good source of calcium for those who need to avoid dairy, providing more calcium per serving than dairy milk, but it does not contain vitamin D.  Other dietary sources of calcium are salmon with bones, tofu, almonds, broccoli, kale, and spinach.

 

            While calcium intake can also be boosted with supplements, it is important to know that a study conducted in 2007 found that those who ate calcium rich foods had higher bone density values than those who relied upon calcium supplements. (2) 

            Calcium supplements are available as calcium citrate and calcium carbonate.  Calcium citrate is 21% calcium and easily absorbed by the body.  Calcium carbonate is 40% calcium but relies upon stomach acids to help absorption and needs to be taken with food.  It is also important to know that calcium in absorbed best in doses equal to or less than 500 mg at a time and that the body’s ability to absorb calcium decreases with age. (3)

            Low bone mineral density is a problem because it leads to weakened bones, stress fractures, and osteoporosis.  It is important for dancers to amass as much bone tissue as possible when they are young, and carefully monitoring their calcium intake is an important part of that process.

(1) Andon, M.B., Peacock, M., Kanerva, R.L, & DeCastro, J.A. (1996). Calcium absorption from apple and orange juice fortified with calcium citrate malate. Journal of American College of Nutrition, 15(3), 313-6.

(2)Napoli, N., Thompson, J., Civitelli, R., Armamento-Villareal, R.C. (2007). Effects of dietary calcium compared with calcium supplements on estrogen metabolism and bone mineral density. American Journal of Clinical Nutrition, 85(5), 1428-33.

(3) Office of Dietary Supplements National Institutes of Health. (2012). Calcium [Fact Sheet]. Retrieved from http://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/

            

Why Dancers May Be At Risk for Stress Fractures and Osteoporosis

"Movement is life. Life is a process. Improve the quality of the process and you improve the quality of life itself." – Moshe Feldenkrais

            Dancers exercise daily. They are constantly on their feet.  They jump, they turn and they constantly apply additional stress to their bones.  The skeleton knows how to respond to this stress, it grows, or models, more bone to support it.  However, studies of ballet dancers have found that they are at risk for stress fractures and that their bone mass measurements, or bone mineral density scores, are equal to or below that of their inactive peers.  How can this be true?  Why isn’t the body doing its job?

            The answer is that the body can only do its job or respond properly if it’s given the right tools and cues.

            Dancers tend to be thin and even underweight.  Less weight means there is less stress put on the bones on a daily basis.  Therefore, even though classes and rehearsals include weight-bearing exercises, the stress on the skeleton is still less than it would be for someone who falls into the ideal or average weight bracket.

            Dancers are known to restrict the amount of food they eat.  There is a constant pressure in the dance community to eat less and look thinner.  Additionally, dancers spend an enormous amount of time doing physical activity.  Large amounts of physical activity burn large amounts of calories.  When that factor is combined with a low or restricted caloric intake, the body is burning more fuel than it is receiving and an energy deficit is created.  Research has linked energy deficits to lower bone mineral density values.

            Restricting food can also lead to diets that are low in nutritional value and high in caffeine.  Diets lacking in nutritional value tend to be low in calcium, which is necessary for bone growth and development.  When you add that caffeine interferes with the body’s ability to absorb calcium, a recipe for a calcium deficit is created.

            Moreover, studies have shown that poor diets can lead to disruptions in the reproductive system.  Research has shown that female dancers go through adolescence and get their first period, or menarche, later than their peers.  This delay in adolescence means there are lower levels of estrogen in the body, and estrogen plays a big role in making sure that the body can absorb the calcium that is eaten.

            Since it is important for the body to create and “stock up” on as much bone as possible during the teen years to avoid fragile bones, it is easy to see why dancers might be at risk for developing osteoporosis.  The good news is that dancers, when armed with some knowledge, can change that.

            Additional weight-bearing exercises can be added to a dancer’s life - weight training and walking can easily be added into a training schedule.  Knowing how to properly fuel the body is important for everyone, but it is especially important for dancers and athletes.  Our next post will help you figure out how to do just that!

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