Adolescent Athlete Bone Health

Bone health is often one of the under appreciated aspects of adolescent athlete health and performance. It is well understood and well documented that adolescence is a time of peak growth and development and this not only includes height, weight and brain development but also bone development. It has been estimated that up to 90 % of bone mineral density is accumulated during adolescence. Thus, this period is one of the most important times nutrition support is needed to promote healthy bone development. Exercise is also a component of healthy bone development during adolescence. Many younger athletes maintain very high activity levels during peak bone development years however they often fall short in fueling properly to maintain healthy bone growth during these high activity times. This can put them at risk for bone stress injuries.  

Proper fueling to maintain healthy bone growth and development in adolescent athletes starts with achieving overall adequate energy intake. When athletes do not consume enough energy throughout the day to fuel both normal growth and development as well as to support exercise they put themselves in a state of low energy availability. This means their body does not have enough energy to fuel both normal biological functioning and exercise so the energy needed for normal biological functioning is stolen for exercise. This can result in a myriad of negative health outcomes including stunted growth, poor bone density, bone stress injuries, loss of menstrual cycle/low testosterone, fatigue, decreased sports performance, and more.

Along with achieving adequate energy intake there are a few key nutrients we want to ensure athletes are consuming to support bone development which are calcium and vitamin D. Low calcium intake can provide inadequate stores for bone development and could lead to stress fractures and possibly low bone mass. Low vitamin D intake can affect the body's ability to absorb and utilize calcium which can lead to inadequate calcium stores for bone development. To support an adolescent athlete’s bone health, achieving adequate calcium and vitamin D is necessary.

Research suggests that many athletes consume too little calcium and vitamin D, especially those attempting to drop weight or those with a vegetarian eating style. The recommended daily intake for calcium and vitamin D are listed below.

Male                                       Calcium                          Vitamin D 

      4-8   year old                           1,000 mg.              600 IU          

      9-18 year old                           1,300 mg               600 IU          

Female

      4-8  year old                            1,000 mg               600 IU          

      9-18 year old                           1,300 mg.              600 IU          

Calcium has many important functions in the body including facilitating the transmission of nerve impulses, supporting cell membranes, supporting hormone health, and most importantly regulating bone health. Ninety-nine percent of the body's calcium stores exists in the bone and teeth. Both adolescent and adult female athletes tend to consume less calcium than their male counterparts. This is a worrisome trend when you consider the amount of hormone and bone health changes that occur in female adolescents that calcium is required to support. In order to improve calcium intake in adolescent athletes, calcium rich foods should be offered at all meals and at least one or two snacks per day. The highest bioavailable form of calcium comes from dairy sources. Other food sources of calcium include deep green vegetables, certain legumes, and fortified foods including tofu, orange juice, cereal or energy bars, and some brands of breads and margarines.

Vitamin D is a very important vitamin and hormone. It plays a key role in calcium absorption. Healthy bone development is not possible without vitamin D. Vitamin D is found in fish, eggs and fortified foods including milk, orange juice, and some yogurt. Most individuals get a majority of their vitamin D from the sun. This can be a concern during winter months and for athletes playing indoor sports where vitamin D intake from food needs to be emphasized.  

Certain nutrients in food have been known to either improve or decrease calcium absorption. For instance, the protein, phosphorus, Vitamin D and lactose in milk will facilitate calcium absorption, whereas, fiber, spinach, bran and excess sodium or soda may decrease absorption. Don’t worry, just try not to use or drink excessive soda, eat too much fiber, and go easy on the bran and spinach. There is a plethora of calcium-fortified foods available, look for foods with at least 20-30 % calcium. The calcium content of a food can be derived from the Nutrition Facts Panel on the label. Simply drop the percentage listed at the bottom of the Nutrition Facts box, and add a zero to calculate the milligrams of calcium in the specified serving of food. For instance: 30 % would be equal to 300 mg.

We hope this blog on bone health was helpful! If you are looking to improve your bone health with nutrition we recommend working with a board certified sports dietitian!